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Strain JM, Ruiz GN, Roberts ST, Rose MJ. Methylation of Si(111) Modulates Molecular Orientation in Perylenediimide Thin Films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:2519-2530. [PMID: 38284168 DOI: 10.1021/acs.langmuir.3c02569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2024]
Abstract
Singlet fission produces a pair of low-energy spin-triplet excitons from a single high-energy spin-singlet exciton. While this process offers the potential to enhance the efficiency of silicon solar cells by ∼30%, meeting this goal requires overlayer materials that can efficiently transport triplet excitons to an underlying silicon substrate. Herein, we demonstrate that the chemical functionalization of silicon surfaces controls the structure of vapor-deposited thin films of perylenediimide (PDI) dyes, which are prototypical singlet fission materials. Using a combination of atomic force microscopy (AFM) and grazing-incidence wide-angle X-ray scattering (GIWAXS), we find terminating Si(111) with either a thin, polar oxide layer (SiOx) or with hydrophobic methyl groups (Si-CH3) alters the structures of the resulting PDI films. While PDI films grown on SiOx are comprised of small crystalline grains that largely adopt an "edge-on" orientation with respect to the silicon surface, films grown on Si-CH3 contain large grains that prefer to align in a "face-on" manner with respect to the substrate. This "face-on" orientation is expected to enhance exciton transport to silicon. Interestingly, we find that the preferred mode of growth for different PDIs correlates with the space group associated with bulk crystals of these compounds. While PDIs that inhabit a monoclinic (P21/c) space group nucleate films by forming tall and sparse crystalline columns, PDIs that inhabit triclinic (P1̅) space groups afford films comprised of uniform, lamellar PDI domains. The results highlight that silicon surface functionalization profoundly impacts PDI thin film growth, and rational selection of a hydrophobic surface that promotes "face-on" adsorption may improve energy transfer to silicon.
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Affiliation(s)
- Jacob M Strain
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Gabriella N Ruiz
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Sean T Roberts
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Michael J Rose
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
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2
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Bedel Pereira E, Bassaler J, Laval H, Holec J, Monflier R, Mesnilgrente F, Salvagnac L, Daran E, Duployer B, Tenailleau C, Gourdon A, Jancarik A, Séguy I. Benzohexacene guide in accurate determination of field effect carrier mobilities in long acenes. RSC Adv 2022; 12:671-680. [PMID: 35425115 PMCID: PMC8697683 DOI: 10.1039/d1ra07808a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 12/09/2021] [Indexed: 11/21/2022] Open
Abstract
Oligoacenes are promising materials in the field of electronic devices since they exhibit high charge carrier mobility and more particularly as a semiconductor in thin film transistors. Herein, we investigate the field effect charge carrier mobility of benzohexacene, recently obtained by cheletropic decarbonylation at moderate temperature. Initially, high performance bottom contact organic thin-film transistors (OTFTs) were fabricated using tetracene to validate the fabrication process. For easier comparison, the geometries and channel sizes of the fabricated devices are the same for the two acenes. The charge transport in OTFTs being closely related to the organic thin film at the dielectric/organic semiconductor interface, the structural and morphological features of the thin films of both materials are therefore studied according to deposition conditions. Finally, by extracting relevant device parameters the benzohexacene based OTFT shows a four-probe contact-corrected hole mobility value of up to 0.2 cm2 V−1 s−1. Four-probes mobility vs. VGS in the linear regime (VDS = −10 V) for benzohexacene based transistor.![]()
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Affiliation(s)
| | - J. Bassaler
- LAAS-CNRS, Université de Toulouse, UPS, 31031 Toulouse, France
| | - H. Laval
- LAAS-CNRS, Université de Toulouse, UPS, 31031 Toulouse, France
| | - J. Holec
- CEMES-CNRS, 29 Rue J. Marvig, 31055 Toulouse, France
| | - R. Monflier
- LAAS-CNRS, Université de Toulouse, UPS, 31031 Toulouse, France
| | - F. Mesnilgrente
- LAAS-CNRS, Université de Toulouse, UPS, 31031 Toulouse, France
| | - L. Salvagnac
- LAAS-CNRS, Université de Toulouse, UPS, 31031 Toulouse, France
| | - E. Daran
- LAAS-CNRS, Université de Toulouse, UPS, 31031 Toulouse, France
| | - B. Duployer
- CIRIMAT, Université de Toulouse, CNRS, Université Toulouse 3 – Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse Cedex 9, France
| | - C. Tenailleau
- CIRIMAT, Université de Toulouse, CNRS, Université Toulouse 3 – Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse Cedex 9, France
| | - A. Gourdon
- CEMES-CNRS, 29 Rue J. Marvig, 31055 Toulouse, France
| | - A. Jancarik
- CEMES-CNRS, 29 Rue J. Marvig, 31055 Toulouse, France
- CRPP, UMR CNRS 5031, Université de Bordeaux, 33600 Pessac, France
| | - I. Séguy
- LAAS-CNRS, Université de Toulouse, UPS, 31031 Toulouse, France
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3
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Niederhausen J, MacQueen RW, Lips K, Aldahhak H, Schmidt WG, Gerstmann U. Tetracene Ultrathin Film Growth on Hydrogen-Passivated Silicon. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:9099-9113. [PMID: 32659091 DOI: 10.1021/acs.langmuir.0c01154] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Inorganic-organic interfaces are important for enhancing the power conversion efficiency of silicon-based solar cells through singlet exciton fission (SF). We elucidated the structure of the first monolayers of tetracene (Tc), an SF molecule, on hydrogen-passivated Si(111) [H-Si(111)] and hydrogenated amorphous Si (a-Si:H) by combining near-edge X-ray absorption fine structure (NEXAFS) and X-ray photoelectron spectroscopy (XPS) experiments with density functional theory (DFT) calculations. For samples grown at or below substrate temperatures of 265 K, the resulting ultrathin Tc films are dominated by almost upright-standing molecules. The molecular arrangement is very similar to the Tc bulk phase, with only a slightly higher average angle between the conjugated molecular plane normal and the surface normal (α) around 77°. Judging from carbon K-edge X-ray absorption spectra, the orientation of the Tc molecules are almost identical when grown on H-Si(111) and a-Si:H substrates as well as for (sub)mono- to several-monolayer coverages. Annealing to room temperature, however, changes the film structure toward a smaller α of about 63°. A detailed DFT-assisted analysis suggests that this structural transition is correlated with a lower packing density and requires a well-chosen amount of thermal energy. Therefore, we attribute the resulting structure to a distinct monolayer configuration that features less inclined, but still well-ordered molecules. The larger overlap with the substrate wave functions makes this arrangement attractive for an optimized interfacial electron transfer in SF-assisted silicon solar cells.
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Affiliation(s)
- Jens Niederhausen
- Department ASPIN, Helmholtz-Zentrum Berlin für Materialen und Energie GmbH, Berlin, Germany
| | - Rowan W MacQueen
- Department ASPIN, Helmholtz-Zentrum Berlin für Materialen und Energie GmbH, Berlin, Germany
| | - Klaus Lips
- Department ASPIN, Helmholtz-Zentrum Berlin für Materialen und Energie GmbH, Berlin, Germany
| | - Hazem Aldahhak
- Lehrstuhl für Theoretische Materialphysik, Universität Paderborn, 33095 Paderborn, Germany
| | - Wolf Gero Schmidt
- Lehrstuhl für Theoretische Materialphysik, Universität Paderborn, 33095 Paderborn, Germany
| | - Uwe Gerstmann
- Lehrstuhl für Theoretische Materialphysik, Universität Paderborn, 33095 Paderborn, Germany
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4
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Capelli R, Da Como E, Kociok-Köhn G, Fontanesi C, Verna A, Pasquali L. Quantitative resonant soft x-ray reflectivity from an organic semiconductor single crystal. J Chem Phys 2019; 150:094707. [DOI: 10.1063/1.5080800] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- R. Capelli
- Dipartimento di Ingegneria “Enzo Ferrari,” Università di Modena e Reggio Emilia, via P. Vivarelli 10, 41125 Modena, Italy
- IOM-CNR Institute, Area Science Park, SS 14 Km, 163.5, Basovizza, 34149 Trieste, Italy
| | - E. Da Como
- Department of Physics, Centre for Photonics and Photonic Materials (CPPM), University of Bath, Claverton Down, Bath BA2 7AY, United Kingdom
| | - G. Kociok-Köhn
- Material and Chemical Characterisation Facility (MC2), University of Bath, Claverton Down, Bath BA2 7AY, United Kingdom
| | - C. Fontanesi
- Dipartimento di Ingegneria “Enzo Ferrari,” Università di Modena e Reggio Emilia, via P. Vivarelli 10, 41125 Modena, Italy
| | - A. Verna
- Dipartimento di Scienze, Università degli Studi Roma Tre, Via della Vasca Navale 84, 00146 Roma, Italy
| | - L. Pasquali
- Dipartimento di Ingegneria “Enzo Ferrari,” Università di Modena e Reggio Emilia, via P. Vivarelli 10, 41125 Modena, Italy
- IOM-CNR Institute, Area Science Park, SS 14 Km, 163.5, Basovizza, 34149 Trieste, Italy
- Department of Physics, University of Johannesburg, P.O. Box 524, Auckland Park 2006, South Africa
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5
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Pithan L, Nabok D, Cocchi C, Beyer P, Duva G, Simbrunner J, Rawle J, Nicklin C, Schäfer P, Draxl C, Schreiber F, Kowarik S. Molecular structure of the substrate-induced thin-film phase of tetracene. J Chem Phys 2018; 149:144701. [PMID: 30316275 DOI: 10.1063/1.5043379] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present a combined experimental and theoretical study to solve the unit-cell and molecular arrangement of the tetracene thin film (TF) phase. TF phases, also known as substrate induced phases (SIPs), are polymorphs that exist at interfaces and decisively impact the functionality of organic thin films, e.g., in a transistor channel, but also change the optical spectra due to the different molecular packing. As SIPs only exist in textured ultrathin films, their structure determination remains challenging compared to bulk materials. Here, we use grazing incidence X-ray diffraction and atomistic simulations to extract the TF unit-cell parameters of tetracene together with the atomic positions within the unit-cell.
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Affiliation(s)
- Linus Pithan
- Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin, Germany
| | - Dmitrii Nabok
- Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin, Germany
| | - Caterina Cocchi
- Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin, Germany
| | - Paul Beyer
- Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin, Germany
| | - Giuliano Duva
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Joseph Simbrunner
- Department of Neuroradiology, Vascular and Interventional Radiology, Medical University Graz, Auenbruggerplatz 9, Graz 8036, Austria
| | - Jonathan Rawle
- Diamond Light Source Ltd, Harwell Campus, Didcot, Oxfordshire, United Kingdom
| | - Chris Nicklin
- Diamond Light Source Ltd, Harwell Campus, Didcot, Oxfordshire, United Kingdom
| | - Peter Schäfer
- Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin, Germany
| | - Claudia Draxl
- Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin, Germany
| | - Frank Schreiber
- Institut für Angewandte Physik, Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany
| | - Stefan Kowarik
- Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489 Berlin, Germany
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6
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Chandran HT, Ng TW, Foo Y, Li HW, Qing J, Liu XK, Chan CY, Wong FL, Zapien JA, Tsang SW, Lo MF, Lee CS. Direct Free Carrier Photogeneration in Single Layer and Stacked Organic Photovoltaic Devices. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1606909. [PMID: 28370454 DOI: 10.1002/adma.201606909] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Indexed: 06/07/2023]
Abstract
High performance organic photovoltaic devices typically rely on type-II P/N junctions for assisting exciton dissociation. Heremans and co-workers recently reported a high efficiency device with a third organic layer which is spatially separated from the active P/N junction; but still contributes to the carrier generation by passing its energy to the P/N junction via a long-range exciton energy transfer mechanism. In this study the authors show that there is an additional mechanism contributing to the high efficiency. Some bipolar materials (e.g., subnaphthalocyanine chloride (SubNc) and subphthalocyanine chloride (SubPc)) are observed to generate free carriers much more effectively than typical organic semiconductors upon photoexcitation. Single-layer devices with SubNc or SubPc sandwiched between two electrodes can give power conversion efficiencies 30 times higher than those of reported single-layer devices. In addition, internal quantum efficiencies (IQEs) of bilayer devices with opposite stacking sequences (i.e., SubNc/SubPc vs SubPc/SubNc) are found to be the sum of IQEs of single layer devices. These results confirm that SubNc and SubPc can directly generate free carriers upon photoexcitation without assistance from a P/N junction. These allow them to be stacked onto each other with reversible sequence or simply stacking onto another P/N junction and contribute to the photocarrier generation.
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Affiliation(s)
- Hrisheekesh Thachoth Chandran
- Center of Super-Diamond and Advanced Films (COSDAF), Department of Chemistry, City University of Hong Kong, Hong Kong SAR, P. R. China
| | - Tsz-Wai Ng
- Center of Super-Diamond and Advanced Films (COSDAF), Department of Chemistry, City University of Hong Kong, Hong Kong SAR, P. R. China
- City University of Hong Kong Shenzhen Research Institute, Shenzhen, 518000, P. R. China
| | - Yishu Foo
- Center of Super-Diamond and Advanced Films (COSDAF), Department of Physics and Materials Sciences, City University of Hong Kong, Hong Kong SAR, P. R. China
| | - Ho-Wa Li
- Department of Physics and Material Sciences, City University of Hong Kong, Hong Kong SAR, P. R. China
| | - Jian Qing
- Center of Super-Diamond and Advanced Films (COSDAF), Department of Chemistry, City University of Hong Kong, Hong Kong SAR, P. R. China
| | - Xiao-Ke Liu
- Center of Super-Diamond and Advanced Films (COSDAF), Department of Chemistry, City University of Hong Kong, Hong Kong SAR, P. R. China
| | - Chiu-Yee Chan
- Center of Super-Diamond and Advanced Films (COSDAF), Department of Chemistry, City University of Hong Kong, Hong Kong SAR, P. R. China
| | - Fu-Lung Wong
- Center of Super-Diamond and Advanced Films (COSDAF), Department of Chemistry, City University of Hong Kong, Hong Kong SAR, P. R. China
| | - Juan Antonio Zapien
- Center of Super-Diamond and Advanced Films (COSDAF), Department of Physics and Materials Sciences, City University of Hong Kong, Hong Kong SAR, P. R. China
| | - Sai-Wing Tsang
- Department of Physics and Material Sciences, City University of Hong Kong, Hong Kong SAR, P. R. China
| | - Ming-Fai Lo
- Center of Super-Diamond and Advanced Films (COSDAF), Department of Chemistry, City University of Hong Kong, Hong Kong SAR, P. R. China
- City University of Hong Kong Shenzhen Research Institute, Shenzhen, 518000, P. R. China
| | - Chun-Sing Lee
- Center of Super-Diamond and Advanced Films (COSDAF), Department of Chemistry, City University of Hong Kong, Hong Kong SAR, P. R. China
- City University of Hong Kong Shenzhen Research Institute, Shenzhen, 518000, P. R. China
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7
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Nahm RK, Engstrom JR. Who’s on first? Tracking in real time the growth of multiple crystalline phases of an organic semiconductor: Tetracene on SiO2. J Chem Phys 2017; 146:052815. [DOI: 10.1063/1.4971288] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- R. K. Nahm
- School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, USA
| | - J. R. Engstrom
- School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, USA
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8
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Pithan L, Beyer P, Bogula L, Zykov A, Schäfer P, Rawle J, Nicklin C, Opitz A, Kowarik S. Direct Photoalignment and Optical Patterning of Molecular Thin Films. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1604382. [PMID: 27906475 DOI: 10.1002/adma.201604382] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Revised: 10/02/2016] [Indexed: 06/06/2023]
Abstract
A novel strategy for direct photoalignment of molecular materials using optothermal re-orientation is introduced. Photoalignment for molecular materials such as the organic semiconductor tetracene is shown, without relying on additional photoreactive dopants or alignment layers. Patterning and polarized light emission, e.g., for polarized organic light emitting diodes is demonstrated.
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Affiliation(s)
- Linus Pithan
- Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489, Berlin, Germany
| | - Paul Beyer
- Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489, Berlin, Germany
| | - Laura Bogula
- Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489, Berlin, Germany
| | - Anton Zykov
- Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489, Berlin, Germany
| | - Peter Schäfer
- Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489, Berlin, Germany
| | - Jonathan Rawle
- Diamond Light Source Ltd, Harwell Science & Innovation Campus, Didcot, Oxfordshire, OX11 0DE, UK
| | - Chris Nicklin
- Diamond Light Source Ltd, Harwell Science & Innovation Campus, Didcot, Oxfordshire, OX11 0DE, UK
| | - Andreas Opitz
- Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489, Berlin, Germany
| | - Stefan Kowarik
- Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, 12489, Berlin, Germany
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9
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Abstract
The dependence of exciton dynamics on the crystalline morphology of tetracene is investigated using time-resolved photoluminescence. Single crystals exhibit relatively slow singlet decays with times that range from 130 to 300 ps depending on the sample. This decay has an activation energy of ∼450 cm(-1) over the temperature range of 200-400 K. Single-crystal samples also exhibit more pronounced quantum beats due to the triplet pair spin coherences. Polycrystalline thin films grown by thermal evaporation have singlet decay times on the order of 70-90 ps with a much weaker temperature dependence. Many thin-film samples also exhibit a red-shifted excimer-like emission. When a polycrystalline thin film is thermally annealed to produce larger crystal domains, single-crystal behavior is recovered. We hypothesize that the different dynamics arise from the ability of singlet excitons in the thin films to sample regions with defects or packing motifs that accelerate singlet fission.
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Affiliation(s)
- Geoffrey B Piland
- Department of Chemistry, University of California, Riverside, Riverside, California 92506, United States
| | - Christopher J Bardeen
- Department of Chemistry, University of California, Riverside, Riverside, California 92506, United States
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10
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Birech Z, Schwoerer M, Schmeiler T, Pflaum J, Schwoerer H. Ultrafast dynamics of excitons in tetracene single crystals. J Chem Phys 2014; 140:114501. [PMID: 24655187 DOI: 10.1063/1.4867696] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Ultrafast exciton dynamics in free standing 200 nm thin tetracene single crystals were studied at room temperature by femtosecond transient absorption spectroscopy in the visible spectral range. The complex spectrally overlapping transient absorption traces of single crystals were systematically deconvoluted. From this, the ultrafast dynamics of the ground, excited, and transition states were identified including singlet exciton fission into two triplet excitons. Fission is generated through both, direct fission of higher singlet states S(n) on a sub-picosecond timescale, and thermally activated fission of the singlet exciton S1 on a 40 ps timescale. The high energy Davydov component of the S1 exciton is proposed to undergo fission on a sub-picoseconds timescale. At high density of triplet excitons their mutual annihilation (triplet-triplet annihilation) occurs on a <10 ps timescale.
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Affiliation(s)
- Zephania Birech
- Laser Research Institute, Stellenbosch University, Stellenbosch 7600, South Africa
| | - Markus Schwoerer
- Department of Physics, University of Bayreuth, Bayreuth, Germany
| | - Teresa Schmeiler
- Experimental Physics VI, University of Würzburg and Bavarian Center for Applied Energy Research, Würzburg, Germany
| | - Jens Pflaum
- Experimental Physics VI, University of Würzburg and Bavarian Center for Applied Energy Research, Würzburg, Germany
| | - Heinrich Schwoerer
- Laser Research Institute, Stellenbosch University, Stellenbosch 7600, South Africa
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