1
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Thrupthika T, Nataraj D, Ramya S, Sangeetha A, Thangadurai TD. Induced UV photon sensing properties in narrow bandgap CdTe quantum dots through controlling hot electron dynamics. Phys Chem Chem Phys 2023; 25:25331-25343. [PMID: 37702661 DOI: 10.1039/d3cp02424e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/14/2023]
Abstract
Mn-doped CdTe (Mn-CdTe) quantum dot (QD) as well as quantum dot solid (QD solid) nanostructures are formed and the established structures are confirmed through HR-TEM analysis. The dynamics of charge carriers in both doped & undoped QD and QD solid structures were investigated by transient absorption (TA) spectroscopy. A slow band edge bleach recovery is obtained for Mn-doped CdTe QD and CdTe QD solid systems at room temperature. Additionally, a blue shifted broad bleach behaviour is identified for the Mn-CdTe QD solid system, which is attributed to hot exciton formation in the solid upon photoexcitation with a higher photon energy than the band gap energy (hν > Eg). This noteworthy process of generation of hot excitons and slow charge recombination occurs by means of a synergetic action of the Mn dopant in the host CdTe QD solid system as well as the extended electronic wave function between the coupled QD solid. Apart from the Mn-assisted delayed relaxation of hot electrons in the QD solid, a suppression in dark current as well as a high ION/IOFF ratio of 3203.12 at 1 V is observed in the Mn-CdTe QD-solid based photosensitized device in the visible region. Furthermore, we were able to improve the UV photon harvesting property in a narrow band gap Mn-CdTe QD solid through reducing the higher excited carrier's energy losses.
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Affiliation(s)
- Thankappan Thrupthika
- Quantum Materials & Devices Laboratory, Department of Physics, Bharathiar University, Coimbatore, Tamil Nadu 641 046, India.
| | - Devaraj Nataraj
- Quantum Materials & Devices Laboratory, Department of Physics, Bharathiar University, Coimbatore, Tamil Nadu 641 046, India.
- UGC-CPEPA Centre for Advanced Studies in Physics for the Development of Solar Energy Materials and Devices, Department of Physics, Bharathiar University, Coimbatore, Tamil Nadu, 641 046, India
| | - Subramaniam Ramya
- Quantum Materials & Devices Laboratory, Department of Physics, Bharathiar University, Coimbatore, Tamil Nadu 641 046, India.
| | - Arumugam Sangeetha
- Quantum Materials & Devices Laboratory, Department of Physics, Bharathiar University, Coimbatore, Tamil Nadu 641 046, India.
| | - T Daniel Thangadurai
- KPR Institute of Engineering and Technology, Coimbatore, Tamil Nadu, 641 407, India.
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2
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Das A, Debnath T. Water-Triggered Chemical Transformation of Perovskite Nanocrystals. Chemistry 2023; 29:e202202475. [PMID: 36259609 DOI: 10.1002/chem.202202475] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Indexed: 12/03/2022]
Abstract
Recently emerged lead-halide perovskite nanocrystals (PNCs) are promising optoelectronic material due to their easy solution processability, wide range of color tunability, as well as very high photoluminescence quantum yield. Despite their significant success in lab-scale optoelectronic applications, the long-term stability becomes the main issue, hindering them towards commercialization. The highly ionic nature of such lead-halide structure makes them extremely unstable in water and air. But a very few groups have taken the advantage of such nature of the crystal structure for water-triggered chemical transformation towards shape, composition, and morphology controlled stable and bright PNCs, which are otherwise difficult to obtain by typical direct approach. Furthermore, using polymer as an encapsulating layer for the PNCs, water-soluble stable PNCs have been prepared. In this review, the recent progress on the water-hexane interface chemistry towards chemical transformation to produce several PNCs is described. Such method not only ensure to yield several shape-controlled perovskites nanocrystals, but also formation of perovskites in aqueous phase that show promising application towards bio-imaging.
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Affiliation(s)
- Avik Das
- Centre for Nanotechnology, Indian Institute of Technology Guwahati (IIT G), Guwahati, Assam, 781039, India
| | - Tushar Debnath
- Centre for Nanotechnology, Indian Institute of Technology Guwahati (IIT G), Guwahati, Assam, 781039, India
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3
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Wang L, Yang G, Zhang B, Zhang X, Liu D, Liang Y, Liang G. Unambiguous spectral characterization on triplet energy transfer from quantum dots mediated by hole transfer competing with other carrier dynamics. OPTICS EXPRESS 2022; 30:47440-47451. [PMID: 36558672 DOI: 10.1364/oe.478579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 11/29/2022] [Indexed: 06/17/2023]
Abstract
Triplet generation by quantum dots (QDs)-sensitized molecules emerges great potential in many applications. However, the mechanism of triplet energy transfer (TET) is still fuzzy especially due to the complicated energy level alignment of QDs and molecules or trap states in QDs. Here, CdSe QDs and 5-tetracene carboxylic acid (TCA) molecules are selected as the triplet donor and acceptor, respectively, to form a TET system. By tuning the band gap of CdSe, the CdSe-TCA complex is exactly designed to present a Type-II like alignment of relative energetics. Coupling the transient absorption and time-resolved fluorescence spectra, all carrier dynamics is distinctly elucidated. Quantitative analysis demonstrates that hole transfer persisting for ∼ 2 ps outcompetes all other carrier dynamics such as electron trapping (∼100 ps level), charge recombination (∼ 5 ns) and the so-called "back transfer charge recombination" (∼50 ns), and thus leads to a hole-transfer-mediated TET process. The low TET yield (∼34.0%) ascribed to electron behavior can be further improved if electron trapping and charge recombination are efficiently suppressed. The observation on distinguishable carrier dynamics attributed to legitimate design of energy level alignment facilitates a better understanding of the TET mechanism from QDs to molecules as well as further development of photoelectronic devices based on such TET systems.
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4
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Wu L, Wang Y, Kurashvili M, Dey A, Cao M, Döblinger M, Zhang Q, Feldmann J, Huang H, Debnath T. Interfacial Manganese‐Doping in CsPbBr
3
Nanoplatelets by Employing a Molecular Shuttle. Angew Chem Int Ed Engl 2022; 61:e202115852. [PMID: 34995399 PMCID: PMC9305410 DOI: 10.1002/anie.202115852] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2021] [Indexed: 11/29/2022]
Abstract
Mn‐doping in cesium lead halide perovskite nanoplatelets (NPls) is of particular importance where strong quantum confinement plays a significant role towards the exciton–dopant coupling. In this work, we report an immiscible bi‐phasic strategy for post‐synthetic Mn‐doping of CsPbX3 (X=Br, Cl) NPls. A systematic study shows that electron‐donating oleylamine acts as a shuttle ligand to transport MnX2 through the water–hexane interface and deliver it to the NPls. The halide anion also plays an essential role in maintaining an appropriate radius of Mn2+ and thus fulfilling the octahedral factor required for the formation of perovskite crystals. By varying the thickness of parent NPls, we can tune the dopant incorporation and, consequently, the exciton‐to‐dopant energy transfer process in doped NPls. Time‐resolved optical measurements offer a detailed insight into the exciton‐to‐dopant energy transfer process. This new approach for post‐synthetic cation doping paves a way towards exploring the cation exchange process in several other halide perovskites at the polar–nonpolar interface.
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Affiliation(s)
- Linzhong Wu
- Chair for Photonics and Optoelectronics Nano-Institute Munich Department of Physics Ludwig-Maximilians-Universität München Königinstr. 10 80539 München Germany
- Institute of Functional Nano and Soft Materials (FUNSOM) Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices Soochow University 199 Ren'ai Road Suzhou 215123 Jiangsu P. R. China
| | - Yiou Wang
- Chair for Photonics and Optoelectronics Nano-Institute Munich Department of Physics Ludwig-Maximilians-Universität München Königinstr. 10 80539 München Germany
| | - Mariam Kurashvili
- Chair for Photonics and Optoelectronics Nano-Institute Munich Department of Physics Ludwig-Maximilians-Universität München Königinstr. 10 80539 München Germany
| | - Amrita Dey
- Chair for Photonics and Optoelectronics Nano-Institute Munich Department of Physics Ludwig-Maximilians-Universität München Königinstr. 10 80539 München Germany
| | - Muhan Cao
- Institute of Functional Nano and Soft Materials (FUNSOM) Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices Soochow University 199 Ren'ai Road Suzhou 215123 Jiangsu P. R. China
| | - Markus Döblinger
- Department of Chemistry Ludwig-Maximilians-Universität München Butenandtstrasse 5–13 (E) 81377 München Germany
| | - Qiao Zhang
- Institute of Functional Nano and Soft Materials (FUNSOM) Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices Soochow University 199 Ren'ai Road Suzhou 215123 Jiangsu P. R. China
| | - Jochen Feldmann
- Chair for Photonics and Optoelectronics Nano-Institute Munich Department of Physics Ludwig-Maximilians-Universität München Königinstr. 10 80539 München Germany
| | - He Huang
- Chair for Photonics and Optoelectronics Nano-Institute Munich Department of Physics Ludwig-Maximilians-Universität München Königinstr. 10 80539 München Germany
- School of Optoelectronic Science and Engineering & Collaborative Innovation Center of Suzhou Nano Science and Technology Soochow University Suzhou 215006 P. R. China
| | - Tushar Debnath
- Chair for Photonics and Optoelectronics Nano-Institute Munich Department of Physics Ludwig-Maximilians-Universität München Königinstr. 10 80539 München Germany
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5
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Debnath T, Wu L, Wang Y, Kurashvili M, Dey A, Cao M, Döblinger M, Zhang Q, Feldmann J, Huang H. Interfacial Manganese‐doping in CsPbBr3 Nanoplatelets by Employing a Molecular Shuttle. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202115852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Tushar Debnath
- Ludwig-Maximilians-Universitat Munchen Physics Chair for Photonics and OptoelectronicsNano-Institute MünchenLudwig-Maximilians-Universität MünchenKöniginstr. 10 80539 Munich GERMANY
| | - Linzhong Wu
- Ludwig-Maximilians-Universität München: Ludwig-Maximilians-Universitat Munchen Department of Physics Königinstr. 10Nano-Institute München 80539 Munich GERMANY
| | - Yiou Wang
- Ludwig-Maximilians-Universitat Munchen Department of Physics Königinstr. 10Nano-Institute München 80539 Munich GERMANY
| | - Mariam Kurashvili
- Ludwig-Maximilians-Universität München: Ludwig-Maximilians-Universitat Munchen Department of Physics Königinstr. 10Nano-Institute München 8-539 Munich GERMANY
| | - Amrita Dey
- Ludwig-Maximilians-Universität München: Ludwig-Maximilians-Universitat Munchen Department of Physics Königinstr. 10Nano-Institute München 80539 Munich GERMANY
| | - Muhan Cao
- Soochow University Institute of Functional Nano & Soft Materials (FUNSOM) 199 Ren’ai Road 215123 Suzhou CHINA
| | - Markus Döblinger
- Ludwig-Maximilians-Universität München: Ludwig-Maximilians-Universitat Munchen Department of Chemistry Butenandtstrasse 5–13 (E) 81377 Munich GERMANY
| | - Qiao Zhang
- Soochow University Institute of Functional Nano & Soft Materials (FUNSOM) 199 Ren’ai Road 215123 Suzhou CHINA
| | - Jochen Feldmann
- Ludwig-Maximilians-Universität München: Ludwig-Maximilians-Universitat Munchen Department of Physics Königinstr. 10Nano-Institute Munich 80539 Munich GERMANY
| | - He Huang
- Ludwig-Maximilians-Universität München: Ludwig-Maximilians-Universitat Munchen Department of Physics Königinstr. 10Nano-Institute Munich 80539 Munich GERMANY
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6
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Ali F, Das S, Banerjee S, Maddala BG, Rana G, Datta A. Intense photoluminescence from Cu-doped CdSe nanotetrapods triggered by ultrafast hole capture. NANOSCALE 2021; 13:14228-14235. [PMID: 34477705 DOI: 10.1039/d1nr03833h] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Brightly photoluminescent Cu-doped CdSe nanotetrapods (NTPs) have been prepared by a modified hot injection method. Their photoluminescence (PL) has a quantum yield of 38% and decays slowly over a few microseconds, while the PL in undoped NTPs has a rather small quantum yield of 1.7% and decays predominantly in tens of picoseconds, with a minor component in the nanosecond time regime. PL spectra of doped NTPs are significantly Stokes shifted compared to the band edge (BE). Efficient PL quenching by a hole scavenger confirms the oxidation state of +I for the dopant ion and establishes hole capture by this ion to be the primary event that leads to the Stokes shifted PL. A fast decay of the photoinduced absorption band, along with a similar decay in PL, observed in a femtosecond optical gating experiment, yields a time constant of about a picosecond for the hole capture from the valence band (VB) by Cu+. The remarkably long PL lifetime in the doped NTPs is ascribed to the decrease in the overlap between the wavefunctions of the photogenerated electrons and the captured hole. Hot carrier relaxation processes, triggered by excitation at energies greater than the band gap, leave their signature in a rise time of few hundreds of femtoseconds, in the ground state bleach recovery kinetics. Hence, a complete picture of exciton dynamics in the doped NTPs has been obtained using ultrafast spectroscopic techniques working in tandem.
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Affiliation(s)
- Fariyad Ali
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India.
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7
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Du N, Cui Y, Zhang L, Yang M. Effect of Mn doping on the electron injection in CdSe/TiO 2 quantum dot sensitized solar cells. Phys Chem Chem Phys 2021; 23:647-656. [PMID: 33332495 DOI: 10.1039/d0cp03866k] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Promotion in power conversion efficiency is an appealing task for quantum dot-sensitized solar cells that have emerged as promising materials for the utilization of clean and sustainable energy. Doping of Mn atoms into quantum dots (QD) has been proven to be one of the effective approaches, although the origin of such a promotion remains controversial. While several procedures are involved in the power conversion process, electron injection from the QD to the semiconductor oxide substrate is focused on in this work using first-principles calculations. Based on the Marcus theory, the electron injection rates are evaluated for the quantum dot-sensitized solar cell models in which the pure and Mn-doped core-shell CdSe clusters are deposited on a semiconductor titanium dioxide substrate. Enhanced rates are obtained for the Mn-doped structure, which is in qualitative agreement with the experiments. A large number of dominant injection channels and strong QD-substrate coupling are responsible for the Mn-induced rate enhancement, which could be achieved by manipulating the band structure mapping between the QD and the semiconductor oxide. By addressing the role of an Mn dopant in the electron injection process, strategies for the promotion of electron injection rates are proposed for the design of quantum dot-sensitized solar cells.
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Affiliation(s)
- Ning Du
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China.
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8
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Maity P, Ghosh HN. Strategies for extending charge separation in colloidal nanostructured quantum dot materials. Phys Chem Chem Phys 2019; 21:23283-23300. [PMID: 31621729 DOI: 10.1039/c9cp03551f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Semiconductor colloidal metal chalcogenides (II-VI) in the form of quantum dots (QDs) and different heterostructures (core/shell, alloys, etc.) are of extensive interest in scientific research for both a fundamental understanding and technological applications because of their quantized size and different optical properties; however, due to their small size, the exciton (bound electron and hole) experiences a strong Coulombic attraction, which has a remarkable impact on the charge separation and photophysical properties of QDs. Thus, to achieve an efficient charge separation, numerous attempts have been made via the formation of different heterostructures, QD/molecular adsorbate (either organic or inorganic) assemblies, etc. These hybrid materials ameliorated the absorption of the incident light as well as charge separation. This article reviews the strategies for extending charge separation in these colloidal nanocrystals (NCs), which is one of the crucial steps to elevate the solar to electrical energy conversion efficiency in a quantum dot-sensitized solar cell (QDSC). The article summarizes the benefits of co-sensitization and experimental shreds of evidence for the multiple charge transfer processes involved in a QDSC. Studies have shown that in the co-sensitization process, prolonged charge separation occurs via the dual behavior of the molecular adsorbate, sensitization (electron injection) and capture of holes from photoexcited QDs. This perspective emphases band edge engineering and control of charge carrier dynamics in various core/shell structures. The impact of colloidal alloy NCs on charge separation and interesting photophysical properties was recapitulated via the steady-state and time-resolved photoluminescence (PL) and femtosecond transient absorption spectroscopic techniques. Finally, the prolonged lifetime and extent of charge separation for these hybrid NCs (or the composites) assisted in the development of a better light harvester as compared to the case of their pure counterparts.
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Affiliation(s)
- Partha Maity
- Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Homi Bhabha National Institute, Mumbai-400085, India.
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9
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Banerjee S, Maddala BG, Ali F, Datta A. Enhancement of the band edge emission of CdSe nano-tetrapods by suppression of surface trapping. Phys Chem Chem Phys 2019; 21:9512-9519. [DOI: 10.1039/c9cp00198k] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Preparation of CdSe nano-tetrapods in a controlled environment to eliminate radiative surface state emission.
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Affiliation(s)
- Sucheta Banerjee
- Department of Chemistry
- Indian Institute of Technology Bombay
- Mumbai – 400 076
- India
| | - Bala Gopal Maddala
- Department of Chemistry
- Indian Institute of Technology Bombay
- Mumbai – 400 076
- India
- IITB-Monash Research Academy
| | - Fariyad Ali
- Department of Chemistry
- Indian Institute of Technology Bombay
- Mumbai – 400 076
- India
| | - Anindya Datta
- Department of Chemistry
- Indian Institute of Technology Bombay
- Mumbai – 400 076
- India
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10
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Maiti S, Dana J, Ghosh HN. Correlating Charge‐Carrier Dynamics with Efficiency in Quantum‐Dot Solar Cells: Can Excitonics Lead to Highly Efficient Devices? Chemistry 2018; 25:692-702. [DOI: 10.1002/chem.201801853] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2018] [Revised: 07/06/2018] [Indexed: 11/06/2022]
Affiliation(s)
- Sourav Maiti
- Radiation & Photochemistry DivisionBhabha Atomic Research Centre Mumbai 400085 India
- Department of ChemistrySavitribai Phule Pune University Ganeshkhind Pune 411007 India
| | - Jayanta Dana
- Radiation & Photochemistry DivisionBhabha Atomic Research Centre Mumbai 400085 India
| | - Hirendra N. Ghosh
- Radiation & Photochemistry DivisionBhabha Atomic Research Centre Mumbai 400085 India
- Institute of Nano Science and Technology Mohali Punjab 160062 India
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11
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Charge carrier dynamics in CdTe/ZnTe core/shell nanocrystals for photovoltaic applications
$$^{\S }$$
§. J CHEM SCI 2018. [DOI: 10.1007/s12039-018-1544-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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12
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Dana J, Maity P, Jana B, Maiti S, Ghosh HN. Concurrent Ultrafast Electron- and Hole-Transfer Dynamics in CsPbBr 3 Perovskite and Quantum Dots. ACS OMEGA 2018; 3:2706-2714. [PMID: 31458549 PMCID: PMC6641258 DOI: 10.1021/acsomega.8b00276] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 02/23/2018] [Indexed: 05/22/2023]
Abstract
Ultrafast charge-transfer (i.e., electron and hole) dynamics has been investigated between the cesium lead bromide (CsPbBr3, CPB) perovskite nanocrystals (NCs) and cadmium selenide (CdSe) quantum dots (QDs) as a new composite material for photocatalytic and photovoltaic applications. The CPB NCs have been synthesized and characterized by high-resolution transmission electron microscopy (HR-TEM) and X-ray diffraction (XRD) pattern. The redox levels (i.e., conduction band (CB) and valence band (VB)) of the CPB NCs and CdSe QDs suggest the feasibility of photoexcited electron transfer from CPB NCs to CdSe QDs and photoexcited hole transfer from CdSe QDs to CPB NCs, and it has been confirmed by both steady-state and time-resolved spectroscopy. To investigate the electron- and hole-transfer dynamics in ultrafast time scale, we have performed femtosecond up-conversion and femtosecond transient absorption studies. The measured electron-transfer time from CPB NCs to CdSe QDs and hole-transfer time from CdSe QDs to CPB NCs were found to be 550 and 750 fs, respectively. Interestingly, the charge-transfer process found to be restricted in CPB/CdSe@CdS core-shell system where electron transfer from CPB NCs to core shell takes place, but the hole transfer from core shell to CPB NCs found to be restricted due to CdS shell making the process thermodynamically nonviable. Our observation has suggested that after the photoexcitation of CPB NCs/CdSe QDs composite system, a charge-separated state is formed where the electrons are localized in CB of CdSe QDs and holes are localized in VB of CPB NCs. This makes the composite system a better material for efficient light harvesting and photocatalytic material as compared to the individual ones.
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Affiliation(s)
- Jayanta Dana
- Radiation
and Photochemistry Division, Bhabha Atomic
Research Centre, Mumbai 400085, India
- Homi
Bhabha National Institute, Anushakti Nagar, Mumbai 400094, India
| | - Partha Maity
- Radiation
and Photochemistry Division, Bhabha Atomic
Research Centre, Mumbai 400085, India
| | - Biswajit Jana
- Radiation
and Photochemistry Division, Bhabha Atomic
Research Centre, Mumbai 400085, India
| | - Sourav Maiti
- Radiation
and Photochemistry Division, Bhabha Atomic
Research Centre, Mumbai 400085, India
- Department
of Chemistry, Savitribai Phule Pune University, Ganeshkhind, Pune 411007, India
| | - Hirendra N. Ghosh
- Radiation
and Photochemistry Division, Bhabha Atomic
Research Centre, Mumbai 400085, India
- Homi
Bhabha National Institute, Anushakti Nagar, Mumbai 400094, India
- Institute
of Nano Science and Technology, Mohali, Punjab 160062, India
- E-mail: ,
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13
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Singhal P, Maity P, Jha SK, Ghosh HN. Metal-Ligand Complex-Induced Ultrafast Charge-Carrier Relaxation and Charge-Transfer Dynamics in CdX (X=S, Se, Te) Quantum Dots Sensitized with Nitrocatechol. Chemistry 2017; 23:10590-10596. [PMID: 28556260 DOI: 10.1002/chem.201701271] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Indexed: 11/10/2022]
Abstract
The present work describes the effect of interfacial complex formation on charge carrier dynamics in CdX (X=S, Se, Te) quantum dots (QDs) sensitized nitro catechol (NCAT). To compare experiments were also carried out with catechol (CAT) where no such complexation was observed. Time-resolved emission studies suggest faster charge separation in CdS(Se)/NCAT system as compared to CdS(Se)/CAT although change in Gibbs free energy for hole transfer is less in former as compared to later. This suggests that complex formation favours charge separation. Similar studies were also carried out in CdTe/NCAT system where hole transfer process was not viable thermodynamically but due to complex formation charge separation was observed. Femtosecond transient absorption studies have been carried out to monitor charge carrier dynamics in early time scale. Transient studies show faster electron cooling in QDs/NCAT system as compared to pure QDs and has been assigned to the complex formation on QDs surface. Interestingly charge recombination dynamics is much faster in QDs/NCAT system as compared to pure QDs which can be attributed to the stronger coupling between QDs and NCAT. Our results suggest a strong metal-ligand complex formation on QDs surface that controls charge carrier dynamics in QDs/molecular adsorbate system and to the best of our knowledge it has never been reported.
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Affiliation(s)
- Pallavi Singhal
- Homi Bhabha National Institute, Mumbai, 400 085, India.,Health Physics Division, Bhabha Atomic Research Centre, Mumbai, 400 085, India
| | - Partha Maity
- Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Mumbai, 400 085, India
| | - Sanjay K Jha
- Homi Bhabha National Institute, Mumbai, 400 085, India.,Health Physics Division, Bhabha Atomic Research Centre, Mumbai, 400 085, India
| | - Hirendra N Ghosh
- Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Mumbai, 400 085, India.,Institute of Nano Science and Technology, Habitat Centre, Mohali, Punjab, 160062, India
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14
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Pradhan N, Das Adhikari S, Nag A, Sarma DD. Luminescence, Plasmonic, and Magnetic Properties of Doped Semiconductor Nanocrystals. Angew Chem Int Ed Engl 2017; 56:7038-7054. [DOI: 10.1002/anie.201611526] [Citation(s) in RCA: 168] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Revised: 01/18/2017] [Indexed: 12/25/2022]
Affiliation(s)
- Narayan Pradhan
- Department of Materials Science; Indian Association for the Cultivation of Science; Kolkata 700032 India
| | - Samrat Das Adhikari
- Department of Materials Science; Indian Association for the Cultivation of Science; Kolkata 700032 India
| | - Angshuman Nag
- Department of Chemistry and Centre for Energy Science; Indian Institute of Science Education and Research, IISER; Pune 411008 India
| | - D. D. Sarma
- Solid State and Structural Chemistry Unit; Indian Institute of Science; Bengaluru 560012 India
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15
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Pradhan N, Das Adhikari S, Nag A, Sarma DD. Dotierte Halbleiter-Nanokristalle: Lumineszenz, plasmonische und magnetische Eigenschaften. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201611526] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Narayan Pradhan
- Department of Materials Science; Indian Association for the Cultivation of Science; Kolkata 700032 Indien
| | - Samrat Das Adhikari
- Department of Materials Science; Indian Association for the Cultivation of Science; Kolkata 700032 Indien
| | - Angshuman Nag
- Department of Chemistry and Centre for Energy Science; Indian Institute of Science Education and Research, IISER; Pune 411008 Indien
| | - D. D. Sarma
- Solid State and Structural Chemistry Unit; Indian Institute of Science; Bengaluru 560012 Indien
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16
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Ghosh A, Jana B, Maiti S, Bera R, Ghosh HN, Patra A. Light Harvesting and Photocurrent Generation in a Conjugated Polymer Nanoparticle-Reduced Graphene Oxide Composite. Chemphyschem 2017; 18:1308-1316. [DOI: 10.1002/cphc.201700174] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Indexed: 12/12/2022]
Affiliation(s)
- Arnab Ghosh
- Department of Materials Science; Indian Association for the Cultivation of Science, Jadavpur; Kolkata 700032 India
| | - Bikash Jana
- Department of Materials Science; Indian Association for the Cultivation of Science, Jadavpur; Kolkata 700032 India
| | - Sourav Maiti
- Radiation and Photochemistry Division; Bhabha Atomic Research Centre; Mumbai 400085 India
- Department of Chemistry; Savitribai Phule Pune University, Ganeshkhind; Pune 411007 India
| | - Rajesh Bera
- Department of Materials Science; Indian Association for the Cultivation of Science, Jadavpur; Kolkata 700032 India
| | - Hirendra N. Ghosh
- Radiation and Photochemistry Division; Bhabha Atomic Research Centre; Mumbai 400085 India
- Institute of Nano Science and Technology; Mohal 160062, Punjab India
| | - Amitava Patra
- Department of Materials Science; Indian Association for the Cultivation of Science, Jadavpur; Kolkata 700032 India
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17
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Debnath T, Parui K, Maiti S, Ghosh HN. An Insight into the Interface through Excited-State Carrier Dynamics for Promising Enhancement of Power Conversion Efficiency in a Mn-Doped CdZnSSe Gradient Alloy. Chemistry 2017; 23:3755-3763. [DOI: 10.1002/chem.201605612] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Indexed: 11/07/2022]
Affiliation(s)
- Tushar Debnath
- Radiation & Photochemistry Division; Bhabha Atomic Research Centre; Mumbai 400 085 India), Fax
| | - Kausturi Parui
- Radiation & Photochemistry Division; Bhabha Atomic Research Centre; Mumbai 400 085 India), Fax
| | - Sourav Maiti
- Radiation & Photochemistry Division; Bhabha Atomic Research Centre; Mumbai 400 085 India), Fax
- Department of Chemistry; Savitribai Phule Pune University; Pune 411007 India
| | - Hirendra N. Ghosh
- Radiation & Photochemistry Division; Bhabha Atomic Research Centre; Mumbai 400 085 India), Fax
- Institute of Nano Science and Technology; Mohali Punjab 16062 India
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18
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Dandpat SS, Sahu PK, Sarkar M. Studies on the Mechanism of Fluorescence Quenching of CdS quantum dots by 2-Amino-7-Nitrofluorene and 2-(N,N-dimethylamino)-7-Nitrofluorene. ChemistrySelect 2016. [DOI: 10.1002/slct.201600076] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Shiba Sundar Dandpat
- School of Chemical Sciences; National Institute of Science Education and Research; Bhimpur-Padanpur, Jatni, Khorda 752050 Odisha India
| | - Prabhat Kumar Sahu
- School of Chemical Sciences; National Institute of Science Education and Research; Bhimpur-Padanpur, Jatni, Khorda 752050 Odisha India
| | - Moloy Sarkar
- School of Chemical Sciences; National Institute of Science Education and Research; Bhimpur-Padanpur, Jatni, Khorda 752050 Odisha India
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19
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Debnath T, Maiti S, Ghosh HN. Unusually Slow Electron Cooling to Charge-Transfer State in Gradient CdTeSe Alloy Nanocrystals Mediated through Mn Atom. J Phys Chem Lett 2016; 7:1359-1367. [PMID: 27003582 DOI: 10.1021/acs.jpclett.6b00348] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We have synthesized Mn-doped CdTeSe gradient alloy nanocrystals (NCs) by a colloidal synthetic method, and charge carrier dynamics have been revealed through ultrafast transient absorption (TA) spectroscopy. Due to the reactivity difference between Te and Se, a CdTe-rich core and CdSe-rich shell have been formed in the CdTeSe alloy with the formation of a gradient type II core-shell structure. Electron paramagnetic resonance studies suggest Mn atoms are located in the surface of the alloy NCs. Steady-state optical absorption and emission studies suggest formation of a charge-transfer (CT) state in which electrons are localized in a CdSe-rich shell and holes are localized in a CdTe-rich core which appears in the red region of the spectra. Electron transfer in the CT state is found to take place in the Marcus inverted region. To understand charge-transfer dynamics in the CdTeSe alloy NCs and to determine the effect of Mn doping on the alloy, ultrafast transient absorption studies have been carried out. In the case of the undoped alloy, formation of the CT state is found to take place through electron relaxation to the conduction band of the CT state with a time of 600 fs and through hole relaxation (from the CdSe-rich state to the CdTe-rich state) to the valence band of the CT state with a time scale of 1 ps. However, electron relaxation in the presence of Mn dopants takes place initially via an electron transfer to the Mn 3d state (d(5)) followed by transfer from the Mn 3d state (d(6)) to the CT state, which has been found to take place with a >700 ps time scale in addition to the hole relaxation time of 2 ps. Charge recombination time of the CT state is found to be extremely slow in the Mn-doped CdTeSe alloy NCs as compared to the undoped one, where the Mn atom acts as an electron storage center.
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Affiliation(s)
- Tushar Debnath
- Radiation & Photochemistry Division, Bhabha Atomic Research Centre , Mumbai 400085, India
| | - Sourav Maiti
- Radiation & Photochemistry Division, Bhabha Atomic Research Centre , Mumbai 400085, India
- Department of Chemistry, Savitribai Phule Pune University , Ganeshkhind, Pune 411007, India
| | - Hirendra N Ghosh
- Radiation & Photochemistry Division, Bhabha Atomic Research Centre , Mumbai 400085, India
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20
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Martín C, Ziółek M, Douhal A. Ultrafast and fast charge separation processes in real dye-sensitized solar cells. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY C-PHOTOCHEMISTRY REVIEWS 2016. [DOI: 10.1016/j.jphotochemrev.2015.12.001] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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21
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Synthesis of Mn-doped zinc blende CdSe nanocrystals for quantum dot-sensitized solar cells. RESEARCH ON CHEMICAL INTERMEDIATES 2016. [DOI: 10.1007/s11164-016-2459-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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22
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Singhal P, Ghorpade PV, Shankarling GS, Singhal N, Jha SK, Tripathi RM, Ghosh HN. Exciton delocalization and hot hole extraction in CdSe QDs and CdSe/ZnS type 1 core shell QDs sensitized with newly synthesized thiols. NANOSCALE 2016; 8:1823-1833. [PMID: 26698125 DOI: 10.1039/c5nr07605f] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The present work describes ultrafast thermalized and hot hole transfer processes from photo-excited CdSe quantum dots (QDs) and CdSe/ZnS core-shell QDs (CSQDs) to newly synthesized thiols. Three thiols namely 2-mercapto-N-phenylacetamide (AAT), 3-mercapto-N-phenylpropanamide (APT) and 3-mercapto-N-(4-methoxyphenyl) propanamide (ADPT) were synthesized and their interaction with both CdSe QDs and CdSe/ZnS CSQDs was monitored. Steady state absorption study suggests the exciton delocalization from CdSe QDs in the presence of the thiols. However similar features were not observed in the presence of a ZnS shell over a CdSe core, instead a broadening in the excitonic peak was observed with both APT and ADPT but not with AAT. This exciton delocalization and broadening in the excitonic peak was also confirmed by ultrafast transient absorption studies. Steady state and time resolved emission studies show hole transfer from photo-excited QDs and CSQDs to the thiols. A signature of hot hole extraction was observed in transient absorption studies which was confirmed by fluorescence upconversion studies. Both hot and thermalized hole transfer rates from CdSe QDs and CdSe/ZnS CSQDs to the thiols were determined using the fluorescence up-conversion technique. Experiments with different ZnS shell thicknesses have been carried out which suggest that hole transfer is possible till 2.5 monolayer of the ZnS shell. To the best of our knowledge we are reporting for the first time the extraction of hot holes from CdSe/ZnS type I CSQDs by a molecular adsorbate.
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Affiliation(s)
- Pallavi Singhal
- Health Physics Division, Bhabha Atomic Research Centre, Mumbai, India.
| | - Prashant V Ghorpade
- Department of Dyestuff Technology, Institute Of Chemical Technology, Mumbai, India.
| | | | - Nancy Singhal
- Department of Chemistry, Indian Institute of Technology, Mumbai, India
| | - Sanjay K Jha
- Health Physics Division, Bhabha Atomic Research Centre, Mumbai, India.
| | - Raj M Tripathi
- Health Physics Division, Bhabha Atomic Research Centre, Mumbai, India.
| | - Hirendra N Ghosh
- Radiation & Photochemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, India.
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23
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Wang Y, Wu B, Yang C, Liu M, Sum TC, Yong KT. Synthesis and Characterization of Mn:ZnSe/ZnS/ZnMnS Sandwiched QDs for Multimodal Imaging and Theranostic Applications. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2016; 12:534-546. [PMID: 26663023 DOI: 10.1002/smll.201503352] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Indexed: 06/05/2023]
Abstract
In this work, a facile aqueous synthesis method is optimized to produce Mn:ZnSe/ZnS/ZnMnS sandwiched quantum dots (SQDs). In this core-shell co-doped system, paramagnetic Mn(2+) ions are introduced as core and shell dopants to generate Mn phosphorescence and enhance the magnetic resonance imaging signal, respectively. T1 relaxivity of the nanoparticles can be improved and manipulated by raising the shell doping level. Steady state and time-resolved optical measurements suggest that, after high level shell doping, Mn phosphorescence of the core can be sustained by the sandwiched ZnS shell. Because the SQDs are free of toxic heavy metal compositions, excellent biocompatibility of the prepared nanocrystals is verified by in vitro MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. To explore the theranostic applications of SQDs, liposome-SQD assemblies are prepared and used for ex vivo optical and magnetic resonance imaging. In addition, these engineered SQDs as nanocarrier for gene delivery in therapy of Panc-1 cancer cells are employed. The therapeutic effects of the nanocrystals formulation are confirmed by gene expression analysis and cell viability assay.
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Affiliation(s)
- Yucheng Wang
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore
| | - Bo Wu
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371, Singapore
| | - Chengbin Yang
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore
| | - Maixian Liu
- Department of Chemistry, University at Buffalo, The State University of New York, Buffalo, NY, 14260, USA
| | - Tze Chien Sum
- School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371, Singapore
| | - Ken-Tye Yong
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore
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24
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Shen Q, Shi X, Fan M, Han L, Wang L, Fan Q. Highly sensitive photoelectrochemical cysteine sensor based on reduced graphene oxide/CdS:Mn nanocomposites. J Electroanal Chem (Lausanne) 2015. [DOI: 10.1016/j.jelechem.2015.10.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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25
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Debnath T, Maity P, Dana J, Ghosh HN. Effect of Molecular Coupling on Ultrafast Electron-Transfer and Charge-Recombination Dynamics in a Wide-Gap ZnS Nanoaggregate Sensitized by Triphenyl Methane Dyes. Chemphyschem 2015; 17:724-30. [DOI: 10.1002/cphc.201500883] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Indexed: 11/12/2022]
Affiliation(s)
- Tushar Debnath
- Radiation & Photochemistry Division; Bhabha Atomic Research Centre, Trombay; Mumbai 400 085 India
| | - Partha Maity
- Radiation & Photochemistry Division; Bhabha Atomic Research Centre, Trombay; Mumbai 400 085 India
| | - Jayanta Dana
- Radiation & Photochemistry Division; Bhabha Atomic Research Centre, Trombay; Mumbai 400 085 India
| | - Hirendra N. Ghosh
- Radiation & Photochemistry Division; Bhabha Atomic Research Centre, Trombay; Mumbai 400 085 India
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26
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Maity P, Debnath T, Chopra U, Ghosh HN. Cascading electron and hole transfer dynamics in a CdS/CdTe core-shell sensitized with bromo-pyrogallol red (Br-PGR): slow charge recombination in type II regime. NANOSCALE 2015; 7:2698-2707. [PMID: 25583154 DOI: 10.1039/c4nr05829a] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Ultrafast cascading hole and electron transfer dynamics have been demonstrated in a CdS/CdTe type II core-shell sensitized with Br-PGR using transient absorption spectroscopy and the charge recombination dynamics have been compared with those of CdS/Br-PGR composite materials. Steady state optical absorption studies suggest that Br-PGR forms strong charge transfer (CT) complexes with both the CdS QD and CdS/CdTe core-shell. Hole transfer from the photo-excited QD and QD core-shell to Br-PGR was confirmed by both steady state and time-resolved emission spectroscopy. Charge separation was also confirmed by detecting electrons in the conduction band of the QD and the cation radical of Br-PGR as measured from femtosecond transient absorption spectroscopy. Charge separation in the CdS/Br-PGR composite materials was found to take place in three different pathways, by transferring the photo-excited hole of CdS to Br-PGR, electron injection from the photo-excited Br-PGR to the CdS QD, and direct electron transfer from the HOMO of Br-PGR to the conduction band of the CdS QD. However, in the CdS/CdTe/Br-PGR system hole transfer from the photo-excited CdS to Br-PGR and electron injection from the photo-excited Br-PGR to CdS take place after cascading through the CdTe shell QD. Charge separation also takes place via direct electron transfer from the Br-PGR HOMO to the conduction band of CdS/CdTe. Charge recombination (CR) dynamics between the electron in the conduction band of the CdS QD and the Br-PGR cation radical were determined by monitoring the bleach recovery kinetics. The CR dynamics were found to be much slower in the CdS/CdTe/Br-PGR system than in the CdS/Br-PGR system. The formation of the strong CT complex and the separation of charges cascading through the CdTe shell help to slow down charge recombination in the type II regime.
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Affiliation(s)
- Partha Maity
- Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Mumbai-400085, India.
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27
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Singhal P, Ghosh HN. Hot-Hole Extraction from Quantum Dot to Molecular Adsorbate. Chemistry 2015; 21:4405-12. [DOI: 10.1002/chem.201405947] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Indexed: 11/11/2022]
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