1
|
Durbin M, Balzer AH, Reynolds JR, Ratcliff EL, Stingelin N, Österholm AM. Role of Side-Chain Free Volume on the Electrochemical Behavior of Poly(propylenedioxythiophenes). Chem Mater 2024; 36:2634-2641. [PMID: 38558922 PMCID: PMC10976628 DOI: 10.1021/acs.chemmater.3c02122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/20/2023] [Revised: 02/25/2024] [Accepted: 02/26/2024] [Indexed: 04/04/2024]
Abstract
Mixed ionic/electronic conducting polymers are versatile systems for, e.g., energy storage, heat management (exploiting electrochromism), and biosensing, all of which require electrochemical doping, i.e., the electrochemical oxidation or reduction of their macromolecular backbones. Electrochemical doping is achieved via electro-injection of charges (i.e., electronic carriers), stabilized via migration of counterions from a supporting electrolyte. Since the choice of the polymer side-chain functionalization influences electrolyte and/or ion sorption and desorption, it in turn affects redox properties, and, thus, electrochemically induced mixed conduction. However, our understanding of how side-chain versus backbone design can increase ion flow while retaining high electronic transport remains limited. Hence, heuristic design approaches have typically been followed. Herein, we consider the redox and swelling behavior of three poly(propylenedioxythiophene) derivatives, P(ProDOT)s, substituted with different side-chain motifs, and demonstrate that passive swelling is controlled by the surface polarity of P(ProDOT) films. In contrast, active swelling under operando conditions (i.e., under an applied bias) is dictated by the local side-chain free volume on the length scale of a monomer unit. Such insights deliver important design criteria toward durable soft electrochemical systems for diverse energy and biosensing platforms and new understanding into electrochemical conditioning ("break-in") in many conducting polymers.
Collapse
Affiliation(s)
- Marlow
M. Durbin
- School
of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Alex H. Balzer
- School
of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - John R. Reynolds
- School
of Materials Science and Engineering, Georgia
Institute of Technology, Atlanta, Georgia 30332, United States
- School
of Chemistry and Biochemistry, Georgia Institute
of Technology, Atlanta, Georgia 30332, United States
| | - Erin L. Ratcliff
- Department
of Chemical and Environmental Engineering, The University of Arizona, Tucson, Arizona 85721-0012, United States
| | - Natalie Stingelin
- School
of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
- School
of Materials Science and Engineering, Georgia
Institute of Technology, Atlanta, Georgia 30332, United States
| | - Anna M. Österholm
- School
of Chemistry and Biochemistry, Georgia Institute
of Technology, Atlanta, Georgia 30332, United States
| |
Collapse
|
2
|
Mohapatra AA, Yual WK, Zhang Y, Samoylov AA, Thurston J, Davis CM, McCarthy DP, Printz AD, Toney MF, Ratcliff EL, Armstrong NR, Greenaway AL, Barlow S, Marder SR. Reducing delamination of an electron-transporting polymer from a metal oxide for electrochemical applications. Chem Commun (Camb) 2024; 60:988-991. [PMID: 38167668 DOI: 10.1039/d3cc05391a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Delamination of the electron-transporting polymer N2200 from indium tin oxide (ITO) in aqueous electrolytes is mitigated by modifying ITO with an azide-functionalized phosphonic acid (PA) which, upon UV irradiation, reacts with the polymer. The optical, electrochemical, and spectroelectrochemical properties of N2200 thin films are retained in aqueous and non-aqueous media.
Collapse
Affiliation(s)
| | - Waleed Kuar Yual
- Department of Chemistry & Biochemistry, University of Arizona, Tucson, AZ, 85721, USA
| | - Yadong Zhang
- Renewable and Sustainable Energy Institute, University of Colorado-Boulder, Boulder, CO, 80309, USA.
| | | | - Jonathan Thurston
- Department of Chemistry, University of Colorado-Boulder, Boulder, CO, 80309, USA
| | - Casey M Davis
- Department of Chemistry, University of Colorado-Boulder, Boulder, CO, 80309, USA
| | - Declan P McCarthy
- Department of Chemistry, University of Colorado-Boulder, Boulder, CO, 80309, USA
| | - Adam D Printz
- Department of Chemical and Environmental Engineering, University of Arizona, Tucson, AZ, 85721, USA
| | - Michael F Toney
- Renewable and Sustainable Energy Institute, University of Colorado-Boulder, Boulder, CO, 80309, USA.
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO 80309, USA
- Materials Science and Engineering, University of Colorado, Boulder, CO 80309, USA
| | - Erin L Ratcliff
- Department of Chemical and Environmental Engineering, University of Arizona, Tucson, AZ, 85721, USA
| | - Neal R Armstrong
- Department of Chemistry & Biochemistry, University of Arizona, Tucson, AZ, 85721, USA
| | - Ann L Greenaway
- Materials, Chemistry, and Computational Science Directorate, National Renewable Energy Laboratory, Golden, CO, 80401, USA
| | - Stephen Barlow
- Renewable and Sustainable Energy Institute, University of Colorado-Boulder, Boulder, CO, 80309, USA.
- Materials, Chemistry, and Computational Science Directorate, National Renewable Energy Laboratory, Golden, CO, 80401, USA
| | - Seth R Marder
- Renewable and Sustainable Energy Institute, University of Colorado-Boulder, Boulder, CO, 80309, USA.
- Department of Chemistry, University of Colorado-Boulder, Boulder, CO, 80309, USA
- Materials Science and Engineering, University of Colorado, Boulder, CO 80309, USA
- Materials, Chemistry, and Computational Science Directorate, National Renewable Energy Laboratory, Golden, CO, 80401, USA
| |
Collapse
|
3
|
Bahri M, Schnaider Tontini F, de Keersmaecker ML, Ratcliff EL, Armstrong NR, Browning ND. FIB Sample Preparation and Low Dose STEM Characterisation Challenges of Hybrid Organic-inorganic Perovskite (HOIP) Solar Cells. Microsc Microanal 2023; 29:115-116. [PMID: 37613287 DOI: 10.1093/micmic/ozad067.050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Affiliation(s)
- M Bahri
- Albert Crewe Centre, University of Liverpool, Liverpool, UK
- Department of Mechanical, Materials and Aerospace Engineering, University of Liverpool, Liverpool, UK
| | - F Schnaider Tontini
- Department of Mechanical, Materials and Aerospace Engineering, University of Liverpool, Liverpool, UK
| | - M L de Keersmaecker
- Department of Chemical and Environmental Engineering, University of Arizona, Tucson, AZ, USA
| | - E L Ratcliff
- Department of Chemical and Environmental Engineering, University of Arizona, Tucson, AZ, USA
- Laboratory for Interface Science of Printable Electronic Materials, University of Arizona, Tucson, AZ, USA
- Institute for Energy Solutions, University of Arizona, Tucson, AZ, USA
| | - N R Armstrong
- Institute for Energy Solutions, University of Arizona, Tucson, AZ, USA
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, USA
| | - N D Browning
- Albert Crewe Centre, University of Liverpool, Liverpool, UK
- Department of Mechanical, Materials and Aerospace Engineering, University of Liverpool, Liverpool, UK
- Physical and Computational Sciences, Pacific Northwest National Lab, Richland, WA, USA
- Sivananthan Laboratories, Bolingbrook, IL, USA
| |
Collapse
|
4
|
Farahat ME, Anderson MA, Martell M, Ratcliff EL, Welch GC. New Perylene Diimide Ink for Interlayer Formation in Air-Processed Conventional Organic Photovoltaic Devices. ACS Appl Mater Interfaces 2022; 14:43558-43567. [PMID: 36099398 DOI: 10.1021/acsami.2c12281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Roll-to-roll coating of conventional organic photovoltaic architectures in air necessitates low work function, electron-harvesting interlayers as the top interface, termed cathode interlayers. Traditional materials based on metal oxides are often not compatible with coating in air and/or green solvents, require thermal annealing, and are limited in feasibility due to interactions with underlying layers. Alternatively, perylene diimide materials offer easily tunable redox properties, are amenable to air coating in green solvents, and are considered champion organic-based cathode interlayers. However, underlying mechanisms of the extraction of photogenerated electrons are less well understood. Herein, we demonstrate the utilization of two N-annulated perylene diimide materials, namely, PDIN-H and CN-PDIN-H, in air-processed conventional organic photovoltaic devices, using the now standard PM6:Y6 photoactive layer. The processing ink formulation using cesium carbonate as a processing agent to solubilize the perylene diimides in suitable green solvents (1-propanol and ethyl acetate) for uniform film formation using spin or slot-die coating on top of the photoactive layer is critical. Cesium carbonate remains in the film, creating hybrid organic/metal salt cathode interlayers. Best organic photovoltaic devices have power conversion efficiencies of 13.2% with a spin-coated interlayer and 13.1% with a slot-die-coated interlayer, superior to control devices using the classic conjugated polyelectrolyte PFN-Br as an interlayer (ca. 12.8%). The cathode interlayers were found to be semi-insulating in nature, and the device performance improvements were attributed to beneficial interfacial effects and electron tunneling through sufficiently thin layers. The efficiencies beyond 13% achieved in air-processed organic photovoltaic devices utilizing slot-die-coated cathode interlayers are among the highest reported so far, opening new opportunities for the fabrication of large-area solar cell modules.
Collapse
Affiliation(s)
- Mahmoud E Farahat
- Department of Chemistry, University of Calgary, 2500 University Drive N.W., Calgary, Alberta T2N 1N4, Canada
| | - Michael A Anderson
- Department of Materials Science and Engineering, The University of Arizona, Tucson, Arizona 85721, United States
| | - Mark Martell
- Department of Chemistry, University of Calgary, 2500 University Drive N.W., Calgary, Alberta T2N 1N4, Canada
| | - Erin L Ratcliff
- Department of Materials Science and Engineering, The University of Arizona, Tucson, Arizona 85721, United States
- Department of Chemistry and Biochemistry, The University of Arizona, 1306 E. University Way, Tucson, Arizona 85721, United States
- Department of Chemical and Environmental Engineering, The University of Arizona, 1133 E. James E Rogers Way, Tucson, Arizona 85721, United States
| | - Gregory C Welch
- Department of Chemistry, University of Calgary, 2500 University Drive N.W., Calgary, Alberta T2N 1N4, Canada
| |
Collapse
|
5
|
Zhang F, Park SY, Yao C, Lu H, Dunfield SP, Xiao C, Uličná S, Zhao X, Du Hill L, Chen X, Wang X, Mundt LE, Stone KH, Schelhas LT, Teeter G, Parkin S, Ratcliff EL, Loo YL, Berry JJ, Beard MC, Yan Y, Larson BW, Zhu K. Metastable Dion-Jacobson 2D structure enables efficient and stable perovskite solar cells. Science 2022; 375:71-76. [PMID: 34822309 DOI: 10.1126/science.abj2637] [Citation(s) in RCA: 61] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The performance of three-dimensional (3D) organic-inorganic halide perovskite solar cells (PSCs) can be enhanced through surface treatment with 2D layered perovskites that have efficient charge transport. We maximized hole transport across the layers of a metastable Dion-Jacobson (DJ) 2D perovskite that tuned the orientational arrangements of asymmetric bulky organic molecules. The reduced energy barrier for hole transport increased out-of-plane transport rates by a factor of 4 to 5, and the power conversion efficiency (PCE) for the 2D PSC was 4.9%. With the metastable DJ 2D surface layer, the PCE of three common 3D PSCs was enhanced by approximately 12 to 16% and could reach approximately 24.7%. For a triple-cation–mixed-halide PSC, 90% of the initial PCE was retained after 1000 hours of 1-sun operation at ~40°C in nitrogen.
Collapse
Affiliation(s)
- Fei Zhang
- Chemistry and Nanoscience Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - So Yeon Park
- Chemistry and Nanoscience Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Canglang Yao
- Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606, USA.,Wright Center for Photovoltaics Innovation and Commercialization, University of Toledo, Toledo, OH 43606, USA
| | - Haipeng Lu
- Chemistry and Nanoscience Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Sean P Dunfield
- Materials Science Center, National Renewable Energy Laboratory, Golden, CO 80401, USA.,Renewable and Sustainable Energy Institute, University of Colorado, Boulder, CO 80309, USA.,Materials Science and Engineering Program, University of Colorado, Boulder, CO 80309, USA
| | - Chuanxiao Xiao
- Materials Science Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Soňa Uličná
- SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Xiaoming Zhao
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Linze Du Hill
- Department of Chemical and Environmental Engineering, University of Arizona, Tucson, AZ 85721, USA
| | - Xihan Chen
- Chemistry and Nanoscience Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Xiaoming Wang
- Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606, USA.,Wright Center for Photovoltaics Innovation and Commercialization, University of Toledo, Toledo, OH 43606, USA
| | - Laura E Mundt
- SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Kevin H Stone
- SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Laura T Schelhas
- Chemistry and Nanoscience Center, National Renewable Energy Laboratory, Golden, CO 80401, USA.,SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Glenn Teeter
- Materials Science Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Sean Parkin
- Department of Chemistry, University of Kentucky, Lexington, KY 40506, USA
| | - Erin L Ratcliff
- Department of Chemical and Environmental Engineering, University of Arizona, Tucson, AZ 85721, USA.,Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA.,Department of Materials Science and Engineering, University of Arizona, Tucson, AZ 85721, USA
| | - Yueh-Lin Loo
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Joseph J Berry
- Materials Science Center, National Renewable Energy Laboratory, Golden, CO 80401, USA.,Renewable and Sustainable Energy Institute, University of Colorado, Boulder, CO 80309, USA.,Department of Physics, University of Colorado, Boulder, CO 80309, USA
| | - Matthew C Beard
- Chemistry and Nanoscience Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Yanfa Yan
- Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606, USA.,Wright Center for Photovoltaics Innovation and Commercialization, University of Toledo, Toledo, OH 43606, USA
| | - Bryon W Larson
- Chemistry and Nanoscience Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Kai Zhu
- Chemistry and Nanoscience Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
| |
Collapse
|
6
|
Du Hill L, De Keersmaecker M, Colbert AE, Hill JW, Placencia D, Boercker JE, Armstrong NR, Ratcliff EL. Rationalizing energy level alignment by characterizing Lewis acid/base and ionic interactions at printable semiconductor/ionic liquid interfaces. Mater Horiz 2022; 9:471-481. [PMID: 34859805 DOI: 10.1039/d1mh01306h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Charge transfer and energy conversion processes at semiconductor/electrolyte interfaces are controlled by local electric field distributions, which can be especially challenging to measure. Herein we leverage the low vapor pressure and vacuum compatibility of ionic liquid electrolytes to undertake a layer-by-layer, ultra-high vacuum deposition of a prototypical ionic liquid EMIM+ (1-ethyl-3-methylimidazolium) and TFSI- (bis(trifluoromethylsulfonyl)-imide) on the surfaces of different electronic materials. We consider a case-by-case study between a standard metal (Au) and four printed electronic materials, where interfaces are characterized by a combination of X-ray and ultraviolet photoemission spectroscopies (XPS/UPS). For template-stripped gold surfaces, we observe through XPS a preferential orientation of the TFSI anion at the gold surface, enabling large electric fields (∼108 eV m-1) within the first two monolayers detected by a large surface vacuum level shift (0.7 eV) in UPS. Conversely, we observe a much more random orientation on four printable semiconductor surfaces: methyl ammonium lead triiodide (MAPbI3), regioregular poly(3-hexylthiophene-2,5-diyl (P3HT)), sol-gel nickel oxide (NiOx), and PbIx-capped PbS quantum dots. For the semiconductors considered, the ionization energy (IE) of the ionic liquid at 3 ML coverage is highly substrate dependent, indicating that underlying chemical reactions are dominating interface level alignment (electronic equilibration) prior to reaching bulk electronic structure. This indicates there is no universal rule for energy level alignment, but that relative strengths of Lewis acid/base sites and ion-molecular interactions should be considered. Specifically, for P3HT, interactions are found to be relatively weak and occurring through the π-bonding structure in the thiophene ring. Alternatively, for NiOx, PbS/PbIx quantum dots, and MAPbI3, our XPS data suggest a combination of ionic bonding and Lewis acid/base reactions between the semiconductor and IL, with MAPbI3 being the most reactive surface. Collectively, our results point towards new directions in interface engineering, where strategically chosen ionic liquid-based anions and cations can be used to preferentially passivate and/or titrate surface defects of heterogeneous surfaces while simultaneously providing highly localized electric fields. These opportunities are expected to be translatable to opto-electronic and electrochemical devices, including energy conversion and storage and biosensing applications.
Collapse
Affiliation(s)
- Linze Du Hill
- Department of Chemical and Environmental Engineering, University of Arizona, 1133 E. James E. Rogers Way, Tucson, AZ 85721, USA.
| | - Michel De Keersmaecker
- Department of Chemical and Environmental Engineering, University of Arizona, 1133 E. James E. Rogers Way, Tucson, AZ 85721, USA.
- Department of Chemistry and Biochemistry, University of Arizona, 1306 E. University Blvd., Tucson, AZ 85721, USA
| | - Adam E Colbert
- US. Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC. 20375, USA
| | - Joshua W Hill
- Department of Chemical and Environmental Engineering, University of Arizona, 1133 E. James E. Rogers Way, Tucson, AZ 85721, USA.
| | - Diogenes Placencia
- US. Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC. 20375, USA
| | - Janice E Boercker
- US. Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC. 20375, USA
| | - Neal R Armstrong
- Department of Chemistry and Biochemistry, University of Arizona, 1306 E. University Blvd., Tucson, AZ 85721, USA
| | - Erin L Ratcliff
- Department of Chemical and Environmental Engineering, University of Arizona, 1133 E. James E. Rogers Way, Tucson, AZ 85721, USA.
- Department of Chemistry and Biochemistry, University of Arizona, 1306 E. University Blvd., Tucson, AZ 85721, USA
- Department of Materials Science and Engineering, University of Arizona, 1235 E. James E. Rogers Way, Tucson, AZ 85721, USA
| |
Collapse
|
7
|
Colbert AE, Placencia D, Ratcliff EL, Boercker JE, Lee P, Aifer EH, Tischler JG. Enhanced Infrared Photodiodes Based on PbS/PbCl x Core/Shell Nanocrystals. ACS Appl Mater Interfaces 2021; 13:58916-58926. [PMID: 34870961 DOI: 10.1021/acsami.1c18263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Improved passivation strategies to address the more complex surface structure of large-diameter nanocrystals are critical to the advancement of infrared photodetectors based on colloidal PbS. In this contribution, the performance of short-wave infrared (SWIR) photodiodes fabricated with PbS/PbClx (core/shell) nanocrystals vs their PbS-only (core) counterparts are directly compared. Devices using PbS cores suffer from shunting and inefficient charge extraction, while core/shell-based devices exhibit greater external quantum efficiencies and lower dark current densities. To elucidate the implications of the shell chemistry on device performance, thickness-dependent energy level offsets and interfacial chemistry of nanocrystal films with the zinc oxide electron-transport layer are evaluated. The disparate device performance between the two synthetic methods is attributed to unfavorable interface dipole formation and surface defect states, associated with inadequate removal of native organic ligands in core-only films. The core/shell system offers a promising route to manage the additional nonpolar (100) surface facets of larger nanocrystals that conventional halide ligand treatments fail to sufficiently passivate.
Collapse
Affiliation(s)
- Adam E Colbert
- U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, District of Columbia 20375, United States
| | - Diogenes Placencia
- U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, District of Columbia 20375, United States
| | - Erin L Ratcliff
- Department of Chemical and Environmental Engineering, University of Arizona, 1133 East James E. Rogers Way, Tucson, Arizona 85721, United States
- Department of Materials Science & Engineering, University of Arizona, 1235 East James E. Rogers Way, Tucson, Arizona 85721, United States
- Chemistry and Biochemistry Department, University of Arizona, 1306 East University Boulevard, Tucson, Arizona 85721, United States
| | - Janice E Boercker
- U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, District of Columbia 20375, United States
| | - Paul Lee
- Chemistry and Biochemistry Department, University of Arizona, 1306 East University Boulevard, Tucson, Arizona 85721, United States
| | - Edward H Aifer
- U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, District of Columbia 20375, United States
| | - Joseph G Tischler
- Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, 440 West Brooks Street, Norman, Oklahoma 73019, United States
| |
Collapse
|
8
|
Yu S, Ratcliff EL. Tuning Organic Electrochemical Transistor (OECT) Transconductance toward Zero Gate Voltage in the Faradaic Mode. ACS Appl Mater Interfaces 2021; 13:50176-50186. [PMID: 34644052 DOI: 10.1021/acsami.1c13009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
In this work, we investigate material design criteria for low-powered/self-powered and efficient organic electrochemical transistors (OECTs) to be operated in the faradaic mode (detection at the gate electrode occurs via electron transfer events). To rationalize device design principles, we adopt a Marcus-Gerischer perspective for electrochemical processes at both the gate and channel interfaces. This perspective considers density of states (DOS) for the semiconductor channel, the gate electrode, and the electrolyte. We complement our approach with energy band offsets of relevant electrochemical potentials that can be independently measured from transistor geometry using conventional electrochemical methods as well as an approach to measure electrolyte potential in an operating OECT. By systematically changing the relative redox property offsets between the redox-active electrolyte and semiconducting polymer channel, we demonstrate a first-order design principle that necessary gate voltage is minimized by good DOS overlap of the two redox processes at the gate and channel. Specifically, for p-type turn-on OECTs, the voltage-dependent, electrochemically active semiconductor DOS should overlap with the oxidant form of the electrolyte to minimize the onset voltage for transconductance. A special case where the electrolyte can be used to spontaneously dope the polymer via charge transfer is also considered. Collectively, our results provide material design pathways toward the development of simple, robust, power-saving, and high-throughput OECT biosensors.
Collapse
Affiliation(s)
- Songyan Yu
- Department of Materials Science and Engineering, The University of Arizona, 1235 E. James E Rogers Way, Tucson, Arizona 85721, United States
| | - Erin L Ratcliff
- Department of Materials Science and Engineering, The University of Arizona, 1235 E. James E Rogers Way, Tucson, Arizona 85721, United States
- Department of Chemical and Environmental Engineering, The University of Arizona, 1133 E. James E Rogers Way, Tucson, Arizona 85721, United States
- Department of Chemistry and Biochemistry, The University of Arizona, 1306 E. University Way, Tucson, Arizona 85721, United States
| |
Collapse
|
9
|
Cieplechowicz E, Munir R, Anderson MA, Ratcliff EL, Welch GC. Zinc Oxide-Perylene Diimide Hybrid Electron Transport Layers for Air-Processed Inverted Organic Photovoltaic Devices. ACS Appl Mater Interfaces 2021; 13:49096-49103. [PMID: 34636554 DOI: 10.1021/acsami.1c15251] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
In this work, we report the formation of perylene diimide films, from green solvents, for use as electron transporting layers, when combined with ZnO, in inverted-type organic photovoltaics. A modified N-annulated PDI was functionalized with a tert-butyloxycarbonyl protecting group to solubilize the material, enabling solution processing from green solvents. Post-deposition treatment of films via thermal annealing cleaves the protecting group yielding the known PDIN-H material, rendering films solvent-resistant. The PDIN-H films were characterized by optical absorption spectroscopy, contact angle measurements, and atomic force microscopy. When used to modify the surface of ZnO in inverted-type organic photovoltaics (air-processed and tested) based on the PM6:Y6 and PTQ10:Y6 bulk-heterojunctions, the device power conversion efficiency increases from 9.8 to 11.0% and 7.2 to 9.8%, respectively.
Collapse
Affiliation(s)
- Edward Cieplechowicz
- Department of Chemistry, University of Calgary, 2500 University Drive N.W., Calgary, Alberta T2N 1N4, Canada
| | - Rahim Munir
- Department of Chemistry, University of Calgary, 2500 University Drive N.W., Calgary, Alberta T2N 1N4, Canada
| | - Michael A Anderson
- Department of Materials Science and Engineering, University of Arizona, Tucson, Arizona 85721, United States
| | - Erin L Ratcliff
- Department of Materials Science and Engineering, University of Arizona, Tucson, Arizona 85721, United States
- Department of Chemical and Environmental Engineering, University of Arizona, Tucson, Arizona 85721, United States
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - Gregory C Welch
- Department of Chemistry, University of Calgary, 2500 University Drive N.W., Calgary, Alberta T2N 1N4, Canada
| |
Collapse
|
10
|
Anderson MA, Larson BW, Ratcliff EL. A Multi-modal Approach to Understanding Degradation of Organic Photovoltaic Materials. ACS Appl Mater Interfaces 2021; 13:44641-44655. [PMID: 34496216 DOI: 10.1021/acsami.1c12321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
State-of-the-art organic photovoltaic (OPV) materials are composed of complex, chemically diverse polymeric and molecular structures that form highly intricate solid-state interactions, collectively yielding exceptional tunability in performance and aesthetics. These properties are especially attractive for semitransparent power-generating windows or shades in living environments, greenhouses, or other architectural integrations. However, before such a future is realized, a broader and deeper understanding of property stability must be acquired. Stability during operating and environmental conditions is critical, namely, material color steadfastness, optoelectronic performance retention, morphological rigidity, and chemical robustness. To date, no single investigation encompasses all four distinct, yet interconnected, metrics. Here, we present a multimodal strategy that captures a dynamic and interconnected evolution of each property during the course of an accelerated photobleaching experiment. We demonstrate this approach across relevant length scales (from molecular to visual macroscale) using X-ray photoelectron spectroscopy, grazing-incidence X-ray scattering, microwave conductivity, and time-dependent photobleaching spectroscopies for two high-performance semitransparent OPV blends-PDPP4T:PC60BM and PDPP4T:IEICO-4F, with comparisons to the stabilities of the individual components. We present direct evidence that specific molecular acceptor (fullerene vs nonfullerene) designs and the resulting donor-acceptor interactions lead to distinctly different mechanistic routes that ultimately arrive at what is termed "OPV degradation." We directly observe a chemical oxidation of the cyano endcaps of the IEICO-4F that coincides with a morphological change and large loss in photoconductivity while the fullerene acceptor-containing blend demonstrates a significantly greater fraction of oxygen uptake but retains 55% of the photoconductivity. This experimental roadmap provides meaningful guidance for future high-throughput, multimodal studies, benchmarking the sensitivity of the different analytical techniques for assessing stability in printable active layers, independent of complete device architectures.
Collapse
Affiliation(s)
- Michael A Anderson
- Department of Materials Science and Engineering, University of Arizona, Tucson, Arizona 85721, United States
| | - Bryon W Larson
- Chemistry and Nanoscience Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Erin L Ratcliff
- Department of Materials Science and Engineering, University of Arizona, Tucson, Arizona 85721, United States
- Department of Chemical and Environmental Engineering, University of Arizona, Tucson, Arizona 85721, United States
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| |
Collapse
|
11
|
Farahat ME, Laventure A, Anderson MA, Mainville M, Tintori F, Leclerc M, Ratcliff EL, Welch GC. Slot-Die-Coated Ternary Organic Photovoltaics for Indoor Light Recycling. ACS Appl Mater Interfaces 2020; 12:43684-43693. [PMID: 32946216 DOI: 10.1021/acsami.0c11809] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Efficient organic photovoltaics (OPVs) based on slot-die-coated (SD) ternary blends were developed for low-intensity indoor light harvesting. For active layers processed in air and from eco-friendly solvents, our device performances (under 1 sun and low light intensity) are the highest reported values for fluoro-dithiophenyl-benzothiadiazole donor polymer-based OPVs. The N-annulated perylene diimide dimer acceptor was incorporated into a blend of donor polymer (FBT) and fullerene acceptor (PC61BM) to give ternary bulk heterojunction blends. SD ternary-based devices under 1 sun illumination showed enhanced power conversion efficiency (PCE) from 6.8 to 7.7%. We observed enhancement in the short-circuit current density and open-circuit voltage of the devices. Under low light intensity light-emitting device illumination (ca. 2000 lux), the ternary-based devices achieved a PCE of 14.0% and a maximum power density of 79 μW/cm2 compared to a PCE of 12.0% and a maximum power density of 68 μW/cm2 for binary-based devices. Under the same illumination conditions, the spin-coated (SC) devices showed a PCE of 15.5% and a maximum power density of 88 μW/cm2. Collectively, these results demonstrate the exceptional promise of a SD ternary blend system for indoor light harvesting and the need to optimize active layers based on industry-relevant coating approaches toward mini modules.
Collapse
Affiliation(s)
- Mahmoud E Farahat
- Department of Chemistry, University of Calgary, 2500 University Drive N.W., Calgary, Alberta T2N 1N4, Canada
| | - Audrey Laventure
- Department of Chemistry, University of Calgary, 2500 University Drive N.W., Calgary, Alberta T2N 1N4, Canada
| | - Michael A Anderson
- Department of Materials Science and Engineering, University of Arizona, Tucson, Arizona 85721, United States
| | - Mathieu Mainville
- Department of Chemistry, Université Laval, Quebec City, Quebec G1V 0A6, Canada
| | - Francesco Tintori
- Department of Chemistry, University of Calgary, 2500 University Drive N.W., Calgary, Alberta T2N 1N4, Canada
| | - Mario Leclerc
- Department of Chemistry, Université Laval, Quebec City, Quebec G1V 0A6, Canada
| | - Erin L Ratcliff
- Department of Materials Science and Engineering, University of Arizona, Tucson, Arizona 85721, United States
- Department of Chemical and Environmental Engineering, University of Arizona, Tucson, Arizona 85721, United States
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - Gregory C Welch
- Department of Chemistry, University of Calgary, 2500 University Drive N.W., Calgary, Alberta T2N 1N4, Canada
| |
Collapse
|
12
|
Watts KE, Neelamraju B, Moser M, McCulloch I, Ratcliff EL, Pemberton JE. Thermally Induced Formation of HF 4TCNQ - in F 4TCNQ-Doped Regioregular P3HT. J Phys Chem Lett 2020; 11:6586-6592. [PMID: 32701299 DOI: 10.1021/acs.jpclett.0c01673] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The prototypical system for understanding doping in solution-processed organic electronics has been poly(3-hexylthiophene) (P3HT) p-doped with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ). Multiple charge-transfer states, defined by the fraction of electron transfer to F4TCNQ, are known to coexist and are dependent on polymer molecular weight, crystallinity, and processing. Less well-understood is the loss of conductivity after thermal annealing of these materials. Specifically, in thermoelectrics, F4TCNQ-doped regioregular (rr) P3HT exhibits significant conductivity losses at temperatures lower than other thiophene-based polymers. Through detailed spectroscopic investigation of progressively heated P3HT films coprocessed with F4TCNQ, we demonstrate that this diminished conductivity is due to formation of the nonchromophoric, weak dopant HF4TCNQ-. This species is likely formed through hydrogen abstraction from the α aliphatic carbon of the hexyl chain at the 3-position of thiophene rings of rr-P3HT. This reaction is eliminated for polymers with ethylene glycol-containing side chains, which retain conductivity at higher operating temperatures. In total, these results provide a critical materials design guideline for organic electronics.
Collapse
Affiliation(s)
| | | | - Maximilian Moser
- Department of Chemistry and Centre for Plastic Electronics, Imperial College London, London, U.K
| | - Iain McCulloch
- Department of Chemistry and Centre for Plastic Electronics, Imperial College London, London, U.K
- KSC, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | | | | |
Collapse
|
13
|
Daviddi E, Chen Z, Beam Massani B, Lee J, Bentley CL, Unwin PR, Ratcliff EL. Nanoscale Visualization and Multiscale Electrochemical Analysis of Conductive Polymer Electrodes. ACS Nano 2019; 13:13271-13284. [PMID: 31674763 DOI: 10.1021/acsnano.9b06302] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Conductive polymers are exceptionally promising for modular electrochemical applications including chemical sensors, bioelectronics, redox-flow batteries, and photoelectrochemical systems due to considerable synthetic tunability and ease of processing. Despite well-established structural heterogeneity in these systems, conventional macroscopic electroanalytical methods-specifically cyclic voltammetry-are typically used as the primary tool for structure-property elucidation. This work presents an alternative correlative multimicroscopy strategy. Data from laboratory and synchrotron-based microspectroscopies, including conducting-atomic force microscopy and synchrotron nanoscale infrared spectroscopy, are combined with potentiodynamic movies of electrochemical fluxes from scanning electrochemical cell microscopy (SECCM) to reveal the relationship between electrode structure and activity. A model conductive polymer electrode system of tailored heterogeneity is investigated, consisting of phase-segregated domains of poly(3-hexylthiophene) (P3HT) surrounded by contiguous regions of insulating poly(methyl methacrylate) (PMMA), representing an ultramicroelectrode array. Isolated domains of P3HT are shown to retain bulk-like chemical and electronic structure when blended with PMMA and possess approximately equivalent electron-transfer rate constants compared to pure P3HT electrodes. The nanoscale electrochemical data are used to model and predict multiscale electrochemical behavior, revealing that macroscopic cyclic voltammograms should be much more kinetically facile than observed experimentally. This indicates that parasitic resistances rather than redox kinetics play a dominant role in macroscopic measurements in these conductive polymer systems. SECCM further demonstrates that the ambient degradation of the P3HT electroactivity within P3HT/PMMA blends is spatially heterogeneous. This work serves as a roadmap for benchmarking the quality of conductive polymer films as electrodes, emphasizing the importance of nanoscale electrochemical measurements in understanding macroscopic properties.
Collapse
Affiliation(s)
- Enrico Daviddi
- Department of Chemistry , University of Warwick , Coventry CV4 7AL , United Kingdom
| | - Zhiting Chen
- Department of Materials Science and Engineering , University of Arizona , Tucson , Arizona 85721 , United States
| | - Brooke Beam Massani
- Department of Chemistry and Biochemistry , University of Arizona , Tucson , Arizona 85721 , United States
| | - Jaemin Lee
- Department of Chemistry , University of Warwick , Coventry CV4 7AL , United Kingdom
| | - Cameron L Bentley
- Department of Chemistry , University of Warwick , Coventry CV4 7AL , United Kingdom
| | - Patrick R Unwin
- Department of Chemistry , University of Warwick , Coventry CV4 7AL , United Kingdom
| | - Erin L Ratcliff
- Department of Materials Science and Engineering , University of Arizona , Tucson , Arizona 85721 , United States
| |
Collapse
|
14
|
Ndione PF, Ratcliff EL, Dey SR, Warren EL, Peng H, Holder AM, Lany S, Gorman BP, Al-Jassim MM, Deutsch TG, Zakutayev A, Ginley DS. High-Throughput Experimental Study of Wurtzite Mn 1-x Zn x O Alloys for Water Splitting Applications. ACS Omega 2019; 4:7436-7447. [PMID: 31459840 PMCID: PMC6648451 DOI: 10.1021/acsomega.8b03347] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 04/02/2019] [Indexed: 05/31/2023]
Abstract
We used high-throughput experimental screening methods to unveil the physical and chemical properties of Mn1-x Zn x O wurtzite alloys and identify their appropriate composition for effective water splitting application. The Mn1-x Zn x O thin films were synthesized using combinatorial pulsed laser deposition, permitting for characterization of a wide range of compositions with x varying from 0 to 1. The solubility limit of ZnO in MnO was determined using the disappearing phase method from X-ray diffraction and X-ray fluorescence data and found to increase with decreasing substrate temperature due to kinetic limitations of the thin-film growth at relatively low temperature. Optical measurements indicate the strong reduction of the optical band gap down to 2.1 eV at x = 0.5 associated with the rock salt-to-wurtzite structural transition in Mn1-x Zn x O alloys. Transmission electron microscopy results show evidence of a homogeneous wurtzite alloy system for a broad range of Mn1-x Zn x O compositions above x = 0.4. The wurtzite Mn1-x ZnxO samples with the 0.4 < x < 0.6 range were studied as anodes for photoelectrochemical water splitting, with a maximum current density of 340 μA cm-2 for 673 nm-thick films. These Mn1-x Zn x O films were stable in pH = 10, showing no evidence of photocorrosion or degradation after 24 h under water oxidation conditions. Doping Mn1-x Zn x O materials with Ga dramatically increases the electrical conductivity of Mn1-x Zn x O up to ∼1.9 S/cm for x = 0.48, but these doped samples are not active in water splitting. Mott-Schottky and UPS/XPS measurements show that the presence of dopant atoms reduces the space charge region and increases the number of mid-gap surface states. Overall, this study demonstrates that Mn1-x Zn x O alloys hold promise for photoelectrochemical water splitting, which could be enhanced with further tailoring of their electronic properties.
Collapse
Affiliation(s)
- Paul F. Ndione
- Materials
Science Center, National Renewable Energy
Laboratory, Golden, Colorado 80401, United States
| | - Erin L. Ratcliff
- Department
of Materials Science and Engineering, The
University of Arizona, Tucson, Arizona 85721, United States
| | - Suhash R. Dey
- Department
of Materials Science and Metallurgical Engineering, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Hyderabad 502285, India
| | - Emily L. Warren
- Materials
Science Center, National Renewable Energy
Laboratory, Golden, Colorado 80401, United States
| | - Haowei Peng
- Materials
Science Center, National Renewable Energy
Laboratory, Golden, Colorado 80401, United States
| | - Aaron M. Holder
- Materials
Science Center, National Renewable Energy
Laboratory, Golden, Colorado 80401, United States
| | - Stephan Lany
- Materials
Science Center, National Renewable Energy
Laboratory, Golden, Colorado 80401, United States
| | - Brian P. Gorman
- Materials
Science Center, National Renewable Energy
Laboratory, Golden, Colorado 80401, United States
- Department
of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Mowafak M. Al-Jassim
- Materials
Science Center, National Renewable Energy
Laboratory, Golden, Colorado 80401, United States
| | - Todd G. Deutsch
- Materials
Science Center, National Renewable Energy
Laboratory, Golden, Colorado 80401, United States
| | - Andriy Zakutayev
- Materials
Science Center, National Renewable Energy
Laboratory, Golden, Colorado 80401, United States
| | - David S. Ginley
- Materials
Science Center, National Renewable Energy
Laboratory, Golden, Colorado 80401, United States
| |
Collapse
|
15
|
Neelamraju B, Watts KE, Pemberton JE, Ratcliff EL. Correlation of Coexistent Charge Transfer States in F 4TCNQ-Doped P3HT with Microstructure. J Phys Chem Lett 2018; 9:6871-6877. [PMID: 30450910 DOI: 10.1021/acs.jpclett.8b03104] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Understanding the interaction between organic semiconductors (OSCs) and dopants in thin films is critical for device optimization. The proclivity of a doped OSC to form free charges is predicated on the chemical and electronic interactions that occur between dopant and host. To date, doping has been assumed to occur via one of two mechanistic pathways: an integer charge transfer (ICT) between the OSC and dopant or hybridization of the frontier orbitals of both molecules to form a partial charge transfer complex (CPX). Using a combination of spectroscopies, we demonstrate that CPX and ICT states are present simultaneously in F4TCNQ-doped P3HT films and that the nature of the charge transfer interaction is strongly dependent on the local energetic environment. Our results suggest a multiphase model, where the local charge transfer mechanism is defined by the electronic driving force, governed by local microstructure in regioregular and regiorandom P3HT.
Collapse
|
16
|
Placencia D, Lee P, Tischler JG, Ratcliff EL. Energy Level Alignment of Molybdenum Oxide on Colloidal Lead Sulfide (PbS) Thin Films for Optoelectronic Devices. ACS Appl Mater Interfaces 2018; 10:24981-24986. [PMID: 30014689 DOI: 10.1021/acsami.8b07651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Interfacial charge transport in optoelectronic devices is dependent on energetic alignment that occurs via a number of physical and chemical mechanisms. Herein, we directly connect device performance with measured thickness-dependent energy-level offsets and interfacial chemistry of 1,2-ethanedithiol-treated lead sulfide (PbS) quantum dots and molybdenum oxide. We show that interfacial energetic alignment results from partial charge transfer, quantified via the chemical ratios of Mo5+ relative to Mo6+. The combined effect mitigates leakage current in both the dark and the light, relative to a metal contact, with an overall improvement in open circuit voltage, fill factor, and short circuit current.
Collapse
Affiliation(s)
- Diogenes Placencia
- U.S. Naval Research Laboratory , 4555 Overlook Avenue Southwest , Washington , D.C. 20375 , United States
| | - Paul Lee
- Department of Chemistry & Biochemistry , University of Arizona , 1306 East University Boulevard , Tucson , Arizona 85721 , United States
| | - Joseph G Tischler
- U.S. Naval Research Laboratory , 4555 Overlook Avenue Southwest , Washington , D.C. 20375 , United States
| | - Erin L Ratcliff
- Department of Materials Science & Engineering , University of Arizona , 1235 East James E. Rogers Way , Tucson , Arizona 85721 , United States
| |
Collapse
|
17
|
Rudolph M, Ratcliff EL. Normal and inverted regimes of charge transfer controlled by density of states at polymer electrodes. Nat Commun 2017; 8:1048. [PMID: 29051498 PMCID: PMC5715087 DOI: 10.1038/s41467-017-01264-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 09/01/2017] [Indexed: 11/24/2022] Open
Abstract
Conductive polymer electrodes have exceptional promise for next-generation bioelectronics and energy conversion devices due to inherent mechanical flexibility, printability, biocompatibility, and low cost. Conductive polymers uniquely exhibit hybrid electronic-ionic transport properties that enable novel electrochemical device architectures, an advantage over inorganic counterparts. Yet critical structure-property relationships to control the potential-dependent rates of charge transfer at polymer/electrolyte interfaces remain poorly understood. Herein, we evaluate the kinetics of charge transfer between electrodeposited poly-(3-hexylthiophene) films and a model redox-active molecule, ferrocenedimethanol. We show that the kinetics directly follow the potential-dependent occupancy of electronic states in the polymer. The rate increases then decreases with potential (both normal and inverted kinetic regimes), a phenomenon distinct from inorganic semiconductors. This insight can be invoked to design polymer electrodes with kinetic selectivity toward redox active species and help guide synthetic approaches for the design of alternative device architectures and approaches.
Collapse
Affiliation(s)
- M Rudolph
- Department of Materials Science and Engineering, University of Arizona, 1235 E. James E. Rogers Way, Tucson, AZ, 85721, USA
| | - E L Ratcliff
- Department of Materials Science and Engineering, University of Arizona, 1235 E. James E. Rogers Way, Tucson, AZ, 85721, USA.
| |
Collapse
|
18
|
Steirer KX, Ou KL, Armstrong NR, Ratcliff EL. Critical Interface States Controlling Rectification of Ultrathin NiO-ZnO p-n Heterojunctions. ACS Appl Mater Interfaces 2017; 9:31111-31118. [PMID: 28832121 DOI: 10.1021/acsami.7b08899] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Herein, we consider the heterojunction formation of two prototypical metal oxides: p-type NiO and n-type ZnO. Elementally abundant, low-cost metal oxide/oxide' heterojunctions are of interest for UV optical sensing, gas sensing, photocatalysis, charge confinement layers, piezoelectric nanogenerators, and flash memory devices. These heterojunctions can also be used as current rectifiers and potentially as recombination layers in tandem photovoltaic stacks by making the two oxide layers ultrathin. In the ultrathin geometry, understanding and control of interface electronic structure and chemical reactions at the oxide/oxide' interface are critical to functionality, as oxygen atoms are shared at the interface of the dissimilar materials. In the studies presented here the extent of chemical reactions and interface band bending is monitored using X-ray and ultraviolet photoelectron spectroscopies. Interface reactivity is controlled by varying the near surface composition of nickel oxide, nickel hydroxide, and nickel oxyhydroxide using standard surface-treatment procedures. A direct correlation between relative percentage of interface hydroxyl chemistry (and hence surface Lewis basicity) and the local band edge alignment for ultrathin p-n junctions (6 nm NiO/30 nm ZnO) is observed. We propose an acid-base formulism to explain these results: the stronger the acid-base reaction, the greater the fraction of interfacial electronic states which lower the band offset between the ZnO conduction band and the NiO valence band. Increased interfacial gap states result in larger reverse bias current of the p-n junction and lower rectification ratios. The acid-base formulism could serve as a future design principle for oxide/oxide' and other heterojunctions based on dissimilar materials.
Collapse
Affiliation(s)
- K Xerxes Steirer
- Department of Chemistry and Biochemistry and ‡Department of Materials Science and Engineering, University of Arizona , Tucson, Arizona 85721, United States
| | - Kai Lin Ou
- Department of Chemistry and Biochemistry and ‡Department of Materials Science and Engineering, University of Arizona , Tucson, Arizona 85721, United States
| | - Neal R Armstrong
- Department of Chemistry and Biochemistry and ‡Department of Materials Science and Engineering, University of Arizona , Tucson, Arizona 85721, United States
| | - Erin L Ratcliff
- Department of Chemistry and Biochemistry and ‡Department of Materials Science and Engineering, University of Arizona , Tucson, Arizona 85721, United States
| |
Collapse
|
19
|
Ratcliff EL, Shallcross RC, Armstrong NR. Introduction: Electronic Materials. Chem Rev 2016; 116:12821-12822. [DOI: 10.1021/acs.chemrev.6b00646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
20
|
McLachlan MA, Ratcliff EL. Metal Oxide Heterointerfaces in Hybrid Electronic Platforms. Adv Mater 2016; 28:3801. [PMID: 27197640 DOI: 10.1002/adma.201601793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Affiliation(s)
- Martyn A McLachlan
- Department of Materials & Centre for Plastic Electronics, Royal School of Mines Imperial, College London, Prince Consort Road, London, SW7 2BP, UK
| | - Erin L Ratcliff
- Department of Materials Science and Engineering, University of Arizona, 1235 E. James E. Rogers Way, Tucson, AZ 85721, USA
| |
Collapse
|
21
|
Fei Z, Boufflet P, Wood S, Wade J, Moriarty J, Gann E, Ratcliff EL, McNeill CR, Sirringhaus H, Kim JS, Heeney M. Influence of Backbone Fluorination in Regioregular Poly(3-alkyl-4-fluoro)thiophenes. J Am Chem Soc 2015; 137:6866-79. [DOI: 10.1021/jacs.5b02785] [Citation(s) in RCA: 177] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Zhuping Fei
- Department
of Chemistry and Centre for Plastic Electronics, Imperial College London, Exhibition Rd, London SW7 2AZ, U.K
| | - Pierre Boufflet
- Department
of Chemistry and Centre for Plastic Electronics, Imperial College London, Exhibition Rd, London SW7 2AZ, U.K
| | - Sebastian Wood
- Department
of Physics and Centre for Plastic Electronics, Imperial College London, Exhibition Rd, London SW7 2AZ, U.K
| | - Jessica Wade
- Department
of Physics and Centre for Plastic Electronics, Imperial College London, Exhibition Rd, London SW7 2AZ, U.K
| | - John Moriarty
- Cavendish
Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE, U.K
| | - Eliot Gann
- Department
of Materials Science and Engineering, Monash University, Clayton, Victoria 3800, Australia
- Australian Synchrotron, 800 Blackburn
Road, Clayton, Victoria 3168, Australia
| | - Erin L. Ratcliff
- Department
of Materials Science and Engineering, University of Arizona, Tucson, Arizona 85721, United States
| | - Christopher R. McNeill
- Department
of Materials Science and Engineering, Monash University, Clayton, Victoria 3800, Australia
| | - Henning Sirringhaus
- Cavendish
Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE, U.K
| | - Ji-Seon Kim
- Department
of Physics and Centre for Plastic Electronics, Imperial College London, Exhibition Rd, London SW7 2AZ, U.K
| | - Martin Heeney
- Department
of Chemistry and Centre for Plastic Electronics, Imperial College London, Exhibition Rd, London SW7 2AZ, U.K
| |
Collapse
|
22
|
Shallcross RC, Stubhan T, Ratcliff EL, Kahn A, Brabec CJ, Armstrong NR. Quantifying the Extent of Contact Doping at the Interface between High Work Function Electrical Contacts and Poly(3-hexylthiophene) (P3HT). J Phys Chem Lett 2015; 6:1303-1309. [PMID: 26263127 DOI: 10.1021/acs.jpclett.5b00444] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We demonstrate new approaches to the characterization of oxidized regioregular poly(3-hexylthiophene-2,5-diyl) (P3HT) that results from electronic equilibration with device-relevant high work function electrical contacts using high-resolution X-ray (XPS) and ultraviolet (UPS) photoelectron spectroscopy (PES). Careful interpretation of photoemission signals from thiophene sulfur atoms in thin (ca. 20 nm or less) P3HT films provides the ability to uniquely elucidate the products of charge transfer between the polymer and the electrical contact, which is a result of Fermi-level equilibration between the two materials. By comparing high-resolution S 2p core-level spectra to electrochemically oxidized P3HT standards, the extent of the contact doping reaction is quantified, where one in every six thiophene units (ca. 20%) in the first monolayer is oxidized. Finally, angle-resolved XPS of both pure P3HT and its blends with phenyl-C61-butyric acid methyl ester (PCBM) confirms that oxidized P3HT species exist near contacts with work functions greater than ca. 4 eV, providing a means to characterize the interface and "bulk" region of the organic semiconductor in a single film.
Collapse
Affiliation(s)
- R Clayton Shallcross
- †Department of Chemistry and Biochemistry, University of Arizona, 1306 East University Boulevard, Tucson, Arizona 85721, United States
| | - Tobias Stubhan
- ‡Institute of Materials for Electronics and Energy Technology (I-MEET), Friedrich-Alexander-University Erlangen-Nuremberg, Martensstrasse 7, Erlangen 91058, Germany
| | - Erin L Ratcliff
- ∥Department of Materials Science and Engineering, University of Arizona, 1235 East James E. Rogers Way, Tucson, Arizona 85721, United States
| | - Antoine Kahn
- §Department of Electrical Engineering, Princeton University, Olden Street, Princeton, New Jersey 08544, United States
| | - Christoph J Brabec
- ‡Institute of Materials for Electronics and Energy Technology (I-MEET), Friedrich-Alexander-University Erlangen-Nuremberg, Martensstrasse 7, Erlangen 91058, Germany
| | - Neal R Armstrong
- †Department of Chemistry and Biochemistry, University of Arizona, 1306 East University Boulevard, Tucson, Arizona 85721, United States
| |
Collapse
|
23
|
Braunecker WA, Oosterhout SD, Owczarczyk ZR, Kopidakis N, Ratcliff EL, Ginley DS, Olson DC. Semi-random vs Well-Defined Alternating Donor-Acceptor Copolymers. ACS Macro Lett 2014; 3:622-627. [PMID: 35590757 DOI: 10.1021/mz5002977] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The influence of backbone composition on the physical properties of donor-acceptor (D-A) copolymers composed of varying amounts of benzodithiophene (BDT) donor with the thienoisoindoledione (TID) acceptor is investigated. First, the synthesis of bis- and tris-BDT monomers is reported; these monomers are subsequently used in Stille copolymerizations to create well-defined alternating polymer structures with repeating (D-A), (D-D-A), and (D-D-D-A) units. For comparison, five semi-random D-A copolymers with a D:A ratio of 1.5, 2, 3, 4, and 7 were synthesized by reacting trimethyltin-functionalized BDT with various ratios of iodinated BDT and brominated TID. While the HOMO levels of all the resultant polymers are very similar, a systematic red shift in the absorbance spectra onset of the D-A copolymer films from 687 to 883 nm is observed with increasing acceptor content, suggesting the LUMO can be fine-tuned over a range of 0.4 eV. When the solid-state absorbance spectra of well-defined alternating copolymers are compared to those of semi-random copolymers with analogous D:A ratios, the spectra of the alternating copolymers are significantly more red-shifted. Organic photovoltaic device efficiencies show that the semi-random materials all outperform the well-defined alternating copolymers, and an optimal D:A ratio of 2 produces the highest efficiency. Additional considerations concerning fine-tuning the lifetimes of the photoconductance transients of copolymer:fullerene films measured by time-resolved microwave conductivity are discussed. Overall, the results of this work indicate that the semi-random approach is a powerful synthetic strategy for fine-tuning the optoelectronic and photophysical properties of D-A materials for a number of systematic studies, especially given the ease with which the D:A ratios in the semi-random copolymers can be tuned.
Collapse
Affiliation(s)
- Wade A. Braunecker
- National
Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States
| | - Stefan D. Oosterhout
- National
Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States
| | - Zbyslaw R. Owczarczyk
- National
Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States
| | - Nikos Kopidakis
- National
Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States
| | - Erin L. Ratcliff
- Department
of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - David S. Ginley
- National
Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States
| | - Dana C. Olson
- National
Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States
| |
Collapse
|
24
|
Matz DL, Ratcliff EL, Meyer J, Kahn A, Pemberton JE. Deciphering the metal-C60 interface in optoelectronic devices: evidence for C60 reduction by vapor deposited Al. ACS Appl Mater Interfaces 2013; 5:6001-6008. [PMID: 23734813 DOI: 10.1021/am400640x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The formation of interfacial midgap states due to the reduction of buckminsterfullerene (C60) to amorphous carbon upon subsequent vapor deposition of Al is confirmed using Raman spectroscopy and X-ray, ultraviolet, and inverse photoemission spectroscopies. We demonstrate that vapor deposition of Al results in n-type doping of C60 due to an electron transfer from Al to the LUMO of C60, resulting in the formation of midgap states near the C60 Fermi level. Raman spectroscopy in ultrahigh vacuum clearly identifies the presence of the C60 anion radical (C60(•-)) as well as amorphous carbon created by further degradation of C60(•-). In contrast, the interface formed by vapor deposition of Ag shows only a slight Ag/C60 interfacial charge displacement with no evidence for complete metal-to-C60 electron transfer to form the anion radical or its further degradation products. These results confirm previous speculations of metal-induced chemical damage of C60 films after Al deposition, which is widely suspected of decreasing charge collection efficiency in OPVs, and provide key insight into charge collection at metal/organic interfaces in such devices.
Collapse
Affiliation(s)
- Dallas L Matz
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| | | | | | | | | |
Collapse
|
25
|
Gliboff M, Sang L, Knesting KM, Schalnat MC, Mudalige A, Ratcliff EL, Li H, Sigdel AK, Giordano AJ, Berry JJ, Nordlund D, Seidler GT, Brédas JL, Marder SR, Pemberton JE, Ginger DS. Orientation of phenylphosphonic acid self-assembled monolayers on a transparent conductive oxide: a combined NEXAFS, PM-IRRAS, and DFT study. Langmuir 2013; 29:2166-2174. [PMID: 23379837 DOI: 10.1021/la304594t] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Self-assembled monolayers (SAMs) of dipolar phosphonic acids can tailor the interface between organic semiconductors and transparent conductive oxides. When used in optoelectronic devices such as organic light emitting diodes and solar cells, these SAMs can increase current density and photovoltaic performance. The molecular ordering and conformation adopted by the SAMs determine properties such as work function and wettability at these critical interfaces. We combine angle-dependent near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) to determine the molecular orientations of a model phenylphosphonic acid on indium zinc oxide, and correlate the resulting values with density functional theory (DFT). We find that the SAMs are surprisingly well-oriented, with the phenyl ring adopting a well-defined tilt angle of 12-16° from the surface normal. We find quantitative agreement between the two experimental techniques and density functional theory calculations. These results not only provide a detailed picture of the molecular structure of a technologically important class of SAMs, but also resolve a long-standing ambiguity regarding the vibrational-mode assignments for phosphonic acids on oxide surfaces, thus improving the utility of PM-IRRAS for future studies.
Collapse
Affiliation(s)
- Matthew Gliboff
- Department of Physics, University of Washington, Seattle, Washington 98195-1560, United States
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
26
|
Garcia A, Welch GC, Ratcliff EL, Ginley DS, Bazan GC, Olson DC. Improvement of interfacial contacts for new small-molecule bulk-heterojunction organic photovoltaics. Adv Mater 2012; 24:5368-5373. [PMID: 22886940 DOI: 10.1002/adma.201200963] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Revised: 05/11/2012] [Indexed: 06/01/2023]
Abstract
The influence of protonation reactions between poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and a thiadiazolo[3,4-c]pyridine small-molecule donor are reported; these result in poor solar-cell performance due to a barrier for charge extraction. The use of a NiO(x) contact eliminates such deleterious chemical interactions and results in substantial improvements in open-circuit voltage, fill factor, and an increased power conversion efficiency from 2.3% to 5.1%.
Collapse
Affiliation(s)
- Andres Garcia
- National Center for Photovoltaics, National Renewable Energy Laboratory, Golden, CO 80401, USA
| | | | | | | | | | | |
Collapse
|
27
|
Lin HC, Polaske NW, Oquendo LE, Gliboff M, Knesting KM, Nordlund D, Ginger DS, Ratcliff EL, Beam BM, Armstrong NR, McGrath DV, Saavedra SS. Electron-Transfer Processes in Zinc Phthalocyanine-Phosphonic Acid Monolayers on ITO: Characterization of Orientation and Charge-Transfer Kinetics by Waveguide Spectroelectrochemistry. J Phys Chem Lett 2012; 3:1154-1158. [PMID: 26288050 DOI: 10.1021/jz3002426] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Using a monolayer of zinc phthalocyanine (ZnPcPA) tethered to indium tin oxide (ITO) as a model for the donor/transparent conducting oxide (TCO) interface in organic photovoltaics (OPVs), we demonstrate the relationship between molecular orientation and charge-transfer rates using spectroscopic, electrochemical, and spectroelectrochemical methods. Both monomeric and aggregated forms of the phthalocyanine (Pc) are observed in ZnPcPA monolayers. Potential-modulated attenuated total reflectance (PM-ATR) measurements show that the monomeric subpopulation undergoes oxidation/reduction with ks,app = 2 × 10(2) s(-1), independent of Pc orientation. For the aggregated ZnPcPA, faster orientation-dependent charge-transfer rates are observed. For in-plane-oriented Pc aggregates, ks,app = 2 × 10(3) s(-1), whereas for upright Pc aggregates, ks,app = 7 × 10(2) s(-1). The rates for the aggregates are comparable to those required for redox-active interlayer films at the hole-collection contact in organic solar cells.
Collapse
Affiliation(s)
- Hsiao-Chu Lin
- †Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - Nathan W Polaske
- †Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - Luis E Oquendo
- †Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| | | | | | - Dennis Nordlund
- #Stanford Synchrotron Radiation Laboratory, 2575 Sand Hill Road MS69, Menlo Park, California 94025, United States
| | | | - Erin L Ratcliff
- †Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - Brooke M Beam
- †Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - Neal R Armstrong
- †Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - Dominic V McGrath
- †Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - S Scott Saavedra
- †Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, United States
| |
Collapse
|
28
|
MacLeod BA, Horwitz NE, Ratcliff EL, Jenkins JL, Armstrong NR, Giordano AJ, Hotchkiss PJ, Marder SR, Campbell CT, Ginger DS. Built-In Potential in Conjugated Polymer Diodes with Changing Anode Work Function: Interfacial States and Deviation from the Schottky-Mott Limit. J Phys Chem Lett 2012; 3:1202-1207. [PMID: 26288056 DOI: 10.1021/jz300283h] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We use electroabsorption spectroscopy to measure the change in built-in potential (VBI) across the polymer photoactive layer in diodes where indium tin oxide electrodes are systematically modified using dipolar phosphonic acid self-assembled monolayers (SAMs) with various dipole moments. We find that VBI scales linearly with the work function (Φ) of the SAM-modified electrode over a wide range when using a solution-coated poly(p-phenylenevinylene) derivative as the active layer. However, we measure an interfacial parameter of S = eΔVBI/ΔΦ < 1, suggesting that these ITO/SAM/polymer interfaces deviate from the Schottky-Mott limit, in contrast to what has previously been reported for a number of ambient-processed organic-on-electrode systems. Our results suggest that the energetics at these ITO/SAM/polymer interfaces behave more like metal/organic interfaces previously studied in UHV despite being processed from solution.
Collapse
Affiliation(s)
- Bradley A MacLeod
- †Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Noah E Horwitz
- †Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Erin L Ratcliff
- ‡Department of Chemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - Judith L Jenkins
- ‡Department of Chemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - Neal R Armstrong
- ‡Department of Chemistry, University of Arizona, Tucson, Arizona 85721, United States
| | - Anthony J Giordano
- §School of Chemistry and Biochemistry, and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Peter J Hotchkiss
- §School of Chemistry and Biochemistry, and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Seth R Marder
- §School of Chemistry and Biochemistry, and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Charles T Campbell
- †Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - David S Ginger
- †Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| |
Collapse
|
29
|
Polaske NW, Lin HC, Tang A, Mayukh M, Oquendo LE, Green JT, Ratcliff EL, Armstrong NR, Saavedra SS, McGrath DV. Phosphonic acid functionalized asymmetric phthalocyanines: synthesis, modification of indium tin oxide, and charge transfer. Langmuir 2011; 27:14900-14909. [PMID: 22047210 DOI: 10.1021/la203126c] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Metalated and free-base A(3)B-type asymmetric phthalocyanines (Pcs) bearing, in the asymmetric quadrant, a flexible alkyl linker of varying chain lengths terminating in a phosphonic acid (PA) group have been synthesized. Two parallel series of asymmetric Pc derivatives bearing aryloxy and arylthio substituents are reported, and their synthesis and characterization through NMR, combustion analysis, and MALDI-MS are described. We also demonstrate the modification of indium tin oxide (ITO) substrates using the PA functionalized asymmetric Pc derivatives and monitoring their electrochemistry. The PA functionalized asymmetric Pcs were anchored to the ITO surface through chemisorption and their electrochemical properties characterized using cyclic voltammetry to investigate the effects of PA structure on the thermodynamics and kinetics of charge transfer. Ionization energies of the modified ITO surfaces were measured using ultraviolet photoemission spectroscopy.
Collapse
Affiliation(s)
- Nathan W Polaske
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
30
|
Abstract
Organic photovoltaic cells (OPVs) are promising solar electric energy conversion systems with impressive recent optimization of active layers. OPV optimization must now be accompanied by the development of new charge-selective contacts and interlayers. This Perspective considers the role of interface science in energy harvesting using OPVs, looking back at early photoelectrochemical (photogalvanic) energy conversion platforms, which suffered from a lack of charge carrier selectivity. We then examine recent platforms and the fundamental aspects of selective harvesting of holes and electrons at opposite contacts. For blended heterojunction OPVs, contact/interlayer design is especially critical because charge harvesting competes with recombination at these same contacts. New interlayer materials can modify contacts to both control work function and introduce selectivity and chemical compatibility with nonpolar active layers and add thermodynamic and kinetic selectivity to charge harvesting. We briefly discuss the surface and interface science required for the development of new interlayer materials and take a look ahead at the challenges yet to be faced in their optimization.
Collapse
|
31
|
Ratcliff EL, Veneman PA, Simmonds A, Zacher B, Huebner D, Saavedra SS, Armstrong NR. A planar, chip-based, dual-beam refractometer using an integrated organic light-emitting diode (OLED) light source and organic photovoltaic (OPV) detectors. Anal Chem 2010; 82:2734-42. [PMID: 20218580 DOI: 10.1021/ac9026109] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We present a simple chip-based refractometer with a central organic light-emitting diode (OLED) light source and two opposed organic photovoltaic (OPV) detectors on an internal reflection element (IRE) substrate, creating a true dual-beam sensor platform. For first-generation platforms, we demonstrate the use of a single heterojunction OLED based on electroluminescence from an Alq(3)/TPD heterojunction (tris-(8-hydroxyquinoline)aluminum/N,N'-bis(3-methylphenyl)-N,N'-diphenylbenzidine) and light detection with planar heterojunction pentacene/C(60) OPVs. The sensor utilizes the considerable fraction of emitted light from conventional thin-film OLEDs that is coupled into guided modes in the IRE, instead of into the forward (display) direction. A ray-optics description is used to describe light throughput and efficiency-limiting factors for light coupling from the OLED into the substrate modes, light traversing through the IRE substrate, and light coupling into the OPV detectors. The arrangement of the OLED at the center of the chip provides for two sensing regions: a "sample" channel and a "reference" channel, with detection of light by independent OPV detectors. This configuration allows for normalization of the sensor response against fluctuations in OLED light output, stability, and local fluctuations (temperature) that might influence sensor response. The dual-beam configuration permits significantly enhanced sensitivity to refractive index changes, relative to single-beam protocols, and is easily integrated into a field-portable instrumentation package. Changes in refractive index (DeltaRI) between 10(-2) and 10(-3) RI units could be detected for single beam operation, with sensitivity increased to DeltaRI approximately 10(-4) RI units when the dual-beam configuration is employed.
Collapse
Affiliation(s)
- Erin L Ratcliff
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721, USA
| | | | | | | | | | | | | |
Collapse
|
32
|
Kim BY, Ratcliff EL, Armstrong NR, Kowalewski T, Pyun J. Ferrocene functional polymer brushes on indium tin oxide via surface-initiated atom transfer radical polymerization. Langmuir 2010; 26:2083-2092. [PMID: 19968255 DOI: 10.1021/la902590u] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The synthesis and electrochemical characterization of ferrocene functional polymethacrylate brushes on indium tin oxide (ITO) electrodes using surface-initiated atom transfer radical polymerization (SI-ATRP) is reported. SI-ATRP of ferrocene-containing methacrylate (FcMA) monomers from a phosphonic acid initiator-modified ITO substrate yielded well-defined homo- and block (co)polymer brushes of varying molar mass (4,000 to 37,000 g/mol). Correlation of both electrochemical properties and brush thicknesses confirmed controlled SI-ATRP from modified ITO surfaces. The preparation of block copolymer brushes with varying sequences of FcMA segments was conducted to interrogate the effects of spacing from the ITO electrode surface on the electrochemical properties of a tethered electroactive film.
Collapse
Affiliation(s)
- Bo Yun Kim
- Department of Chemistry, University of Arizona, 1306 E. University Boulevard, Tucson, Arizona 85721, USA
| | | | | | | | | |
Collapse
|
33
|
Ratcliff EL, Lee PA, Armstrong NR. Work function control of hole-selective polymer/ITO anode contacts: an electrochemical doping study. ACTA ACUST UNITED AC 2010. [DOI: 10.1039/b923201j] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
34
|
Keng PY, Kim BY, Shim IB, Sahoo R, Veneman PE, Armstrong NR, Yoo H, Pemberton JE, Bull MM, Griebel JJ, Ratcliff EL, Nebesny KG, Pyun J. Colloidal polymerization of polymer-coated ferromagnetic nanoparticles into cobalt oxide nanowires. ACS Nano 2009; 3:3143-3157. [PMID: 19799415 DOI: 10.1021/nn900483w] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The preparation of polystyrene-coated cobalt oxide nanowires is reported via the colloidal polymerization of polymer-coated ferromagnetic cobalt nanoparticles (PS-CoNPs). Using a combination of dipolar nanoparticle assembly and a solution oxidation of preorganized metallic colloids, interconnected nanoparticles of cobalt oxide spanning micrometers in length were prepared. The colloidal polymerization of PS-CoNPs into cobalt oxide (CoO and Co(3)O(4)) nanowires was achieved by bubbling O(2) into PS-CoNP dispersions in 1,2-dichlorobenzene at 175 degrees C. Calcination of thin films of PS-coated cobalt oxide nanowires afforded Co(3)O(4) metal oxide materials. Transmission electron microscopy (TEM) revealed the formation of interconnected nanoparticles of cobalt oxide with hollow inclusions, arising from a combination of dipolar assembly of PS-CoNPs and the nanoscale Kirkendall effect in the oxidation reaction. Using a wide range of spectroscopic and electrochemical characterization techniques, we demonstrate that cobalt oxide nanowires prepared via this novel methodology were electroactive with potential applications as nanostructured electrodes for energy storage.
Collapse
Affiliation(s)
- Pei Yuin Keng
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721, USA
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
35
|
Ratcliff EL, Hillier AC. Directed electrodeposition of polymer films using spatially controllable electric field gradients. Langmuir 2007; 23:9905-10. [PMID: 17696551 DOI: 10.1021/la700827w] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
We report a method for the directed electrodeposition of polymer films in various patterns using spatially controllable electric field gradients. One- and two- dimensional surface electric field gradients were produced by applying different potential values at spatially distinct locations on an electrode surface. Variations in the resulting local electrochemical potentials were used to spatially manipulate the rate of electrodeposition of several polymers. By controlling the electric field gradient in the presence of sequentially varying deposition solutions, complex polymer patterns could be produced. One-dimensional structures consisting of alternating bands of polyaniline and either poly(phenylene) oxide or poly(aminophenylene) oxide were produced, as well as more complex two-dimensional structures. Film characterization was achieved through optical imaging, UV-vis spectroscopy, and ellipsometry. Results indicate that this directed deposition technique is a simple strategy to create complex, millimeter-sized surface patterns of electrodeposited materials.
Collapse
Affiliation(s)
- Erin L Ratcliff
- Department of Chemical Engineering and Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA
| | | |
Collapse
|