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Li Y, Li P, Lu ZH. Mapping Energy Levels for Organic Heterojunctions. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1700414. [PMID: 28436573 DOI: 10.1002/adma.201700414] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Revised: 03/02/2017] [Indexed: 06/07/2023]
Abstract
An organic semiconductor thin film is a solid-state matter comprising one or more molecules. For applications in electronics and photonics, several distinct functional organic thin films are stacked together to create a variety of devices such as organic light-emitting diodes and organic solar cells. The energy levels at these thin-film junctions dictate various electronic processes such as the charge transport across these junctions, the exciton dissociation rates at donor-acceptor molecular interfaces, and the charge trapping during exciton formation in a host-dopant system. These electronic processes are vital to a device's performance and functionality. To uncover a general scientific principle in governing the interface energy levels, highest occupied molecular orbitals, and vacuum level dipoles, herein a comprehensive experimental research is conducted on several dozens of organic-organic heterojunctions representative of various device applications. It is found that the experimental data map on interface energy levels, after correcting variables such as molecular orientation-dependent ionization energies, consists of three distinct regions depending on interface fundamental physical parameters such as Fermi energy, work function, highest occupied molecular orbitals, and lowest unoccupied molecular orbitals. This general energy map provides a master guide in selection of new materials for fabricating future generations of organic semiconductor devices.
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Affiliation(s)
- Yiying Li
- Department of Materials Science and Engineering, University of Toronto, 184 College Street, Toronto, Ontario, M5S 3E4, Canada
| | - Peicheng Li
- Department of Materials Science and Engineering, University of Toronto, 184 College Street, Toronto, Ontario, M5S 3E4, Canada
| | - Zheng-Hong Lu
- Department of Materials Science and Engineering, University of Toronto, 184 College Street, Toronto, Ontario, M5S 3E4, Canada
- Department of Physics, Yunnan University, Yunnan, 650091, China
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Singh A, Gupta SK, Garg A. Inkjet printing of NiO films and integration as hole transporting layers in polymer solar cells. Sci Rep 2017; 7:1775. [PMID: 28496134 PMCID: PMC5431859 DOI: 10.1038/s41598-017-01897-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Accepted: 04/04/2017] [Indexed: 11/17/2022] Open
Abstract
Stability concerns of organic solar cell devices have led to the development of alternative hole transporting layers such as NiO which lead to superior device life times over conventional Poly(3,4-ethylenedioxythiophene) Polystyrene sulfonate (PEDOT:PSS) buffered solar cells. From the printability of such devices, it is imperative to be able to print NiO layers in the organic solar cell devices with normal architecture which has so far remained unreported. In this manuscript, we report on the successful ink-jet printing of very thin NiO thin films with controlled thickness and morphology and their integration in organic solar cell devices. The parameters that were found to strongly affect the formation of a thin yet continuous NiO film were substrate surface treatment, drop spacing, and substrate temperature during printing. The effect of these parameters was investigated through detailed morphological characterization using optical and atomic force microscopy and the results suggested that one can achieve a transmittance of ~89% for a ~18 nm thin NiO film with uniform structure and morphology, fabricated using a drop spacing of 50 μm and a heat treatment temperature of 400 °C. The devices fabricated with printed NiO hole transporting layers exhibit power conversion efficiencies comparable to the devices with spin coated NiO films.
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Affiliation(s)
- Arjun Singh
- Department of Materials Science and Engineering, Indian Institute of Technology Kanpur, Kanpur, 208016, India
| | - Shailendra Kumar Gupta
- Department of Materials Science and Engineering, Indian Institute of Technology Kanpur, Kanpur, 208016, India
| | - Ashish Garg
- Department of Materials Science and Engineering, Indian Institute of Technology Kanpur, Kanpur, 208016, India.
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Franco Jr. F. Computational study on the structural and optoelectronic properties of a carbazole-benzothiadiazole based conjugated oligomer with various alkyl side-chain lengths. MOLECULAR SIMULATION 2016. [DOI: 10.1080/08927022.2016.1250267] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Francisco Franco Jr.
- Chemistry Department, De La Salle University, Manila, Philippines
- Computational Materials Design Research Unit, Center for Natural Sciences and Ecological Research, De La Salle University, Manila, Philippines
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Franco FC, Padama AAB. DFT and TD-DFT study on the structural and optoelectronic characteristics of chemically modified donor-acceptor conjugated oligomers for organic polymer solar cells. POLYMER 2016. [DOI: 10.1016/j.polymer.2016.05.025] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Zhang W, Pan X, Feng X, Wang CH, Yang YW, Ju H, Zhu J. Interface properties between a low band gap conjugated polymer and a calcium metal electrode. Phys Chem Chem Phys 2016; 18:9446-52. [PMID: 26979721 DOI: 10.1039/c5cp08066e] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Interfaces between metal electrodes and π-conjugated polymers play an important role in the organic optoelectronic devices. In this paper, the molecular orientation of the pristine poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (APFO3) films, chemical reactions and the electronic structure during the interface formation of Ca/APFO3 have been investigated in detail using synchrotron radiation photoemission spectroscopy (SRPES), X-ray photoemission spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. It is shown that the APFO3 film has a high degree of orientational ordering with its aromatic ring tilted at an angle of 43° from the substrate, and the 9,9-dioctyl fluorene unit (F8) is almost in the same plane as the benzothiazole unit (BT). Upon vapor-deposition of Ca onto APFO3 at room temperature, Ca dopes electrons into APFO3 and induces the downward band bending of APFO3. Moreover, Ca can diffuse into the APFO3 subsurface and react with N, S and C atoms of APFO3. Finally, the barrier of electron injection at the Ca/APFO3 interface is derived by the energy level alignment diagram. These results enable us to gain comprehensive insights into APFO3 and will facilitate the reasonable design of high performance devices based on APFO3.
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Affiliation(s)
- Wei Zhang
- National Synchrotron Radiation Laboratory and Collaborative Innovation Center of Suzhou Nano Science and Technology, University of Science and Technology of China, Hefei, Anhui 230029, China. and Hefei Science Center, Chinese Academy of Sciences, China
| | - Xiao Pan
- National Synchrotron Radiation Laboratory and Collaborative Innovation Center of Suzhou Nano Science and Technology, University of Science and Technology of China, Hefei, Anhui 230029, China.
| | - Xuefei Feng
- National Synchrotron Radiation Laboratory and Collaborative Innovation Center of Suzhou Nano Science and Technology, University of Science and Technology of China, Hefei, Anhui 230029, China.
| | - Chia-Hsin Wang
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Yaw-Wen Yang
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
| | - Huanxin Ju
- National Synchrotron Radiation Laboratory and Collaborative Innovation Center of Suzhou Nano Science and Technology, University of Science and Technology of China, Hefei, Anhui 230029, China. and Hefei Science Center, Chinese Academy of Sciences, China
| | - Junfa Zhu
- National Synchrotron Radiation Laboratory and Collaborative Innovation Center of Suzhou Nano Science and Technology, University of Science and Technology of China, Hefei, Anhui 230029, China. and Hefei Science Center, Chinese Academy of Sciences, China
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Kraft M, Adamczyk S, Polywka A, Zilberberg K, Weijtens C, Meyer J, Görrn P, Riedl T, Scherf U. Polyanionic, alkylthiosulfate-based thiol precursors for conjugated polymer self-assembly onto gold and silver. ACS APPLIED MATERIALS & INTERFACES 2014; 6:11758-11765. [PMID: 24995578 DOI: 10.1021/am5025148] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Anionic, conjugated thiophene- and fluorene-based polyelectrolytes with alkylthiosulfate side chains undergo hydrolysis under formation of alkylthiol and dialkyldisulfide functions. The hydrolysis products can be deposited onto gold or silver surfaces by self-assembly from solutions of the anionic conjugated polyelectrolyte (CPE) precursors in polar solvents such as methanol. This procedure allows solution-based surface modifications of gold and silver electrodes using environmentally friendly solvents and enables the formation of conjugated polymer bilayers. The herein presented alkylthiosulfate-substituted CPEs are promising candidates for increasing the work function of gold and silver electrodes thus improving hole injection from such electrode assemblies into organic semiconductors.
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Affiliation(s)
- Mario Kraft
- Bergische Universität Wuppertal , Macromolecular Chemistry Group (buwmakro) and Institut für Polymertechnlogie (IfP), Gauss-Strasse 20, D-42119 Wuppertal, Germany
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Jäger M, Trattnig R, Postl M, Haas W, Kunert B, Resel R, Hofer F, Klug A, Trimmel G, List EJW. Influence of the bridging atom in fluorene analogue low-bandgap polymers on photophysical and morphological properties of copper indium sulfide/polymer nanocomposite solar cells. ACTA ACUST UNITED AC 2013. [DOI: 10.1002/polb.23350] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Monika Jäger
- NanoTecCenter Weiz Forschungsgesellschaft mbH; Franz-Pichler-Straße 32 8160 Weiz Austria
- Christian Doppler Laboratory for Nanocomposite Solar Cells; Graz University of Technology and NanoTecCenter Weiz Forschungsgesellschaft mbH; Austria
| | - Roman Trattnig
- NanoTecCenter Weiz Forschungsgesellschaft mbH; Franz-Pichler-Straße 32 8160 Weiz Austria
- Christian Doppler Laboratory for Nanocomposite Solar Cells; Graz University of Technology and NanoTecCenter Weiz Forschungsgesellschaft mbH; Austria
| | - Markus Postl
- NanoTecCenter Weiz Forschungsgesellschaft mbH; Franz-Pichler-Straße 32 8160 Weiz Austria
- Christian Doppler Laboratory for Nanocomposite Solar Cells; Graz University of Technology and NanoTecCenter Weiz Forschungsgesellschaft mbH; Austria
| | - Wernfried Haas
- Institute for Electron Microscopy and Fine Structure Research; Graz University of Technology; Steyrergasse 17 8010 Graz Austria
| | - Birgit Kunert
- Institute of Solid State Physics; Graz University of Technology; Petersgasse 16 8010 Graz Austria
| | - Roland Resel
- Institute of Solid State Physics; Graz University of Technology; Petersgasse 16 8010 Graz Austria
| | - Ferdinand Hofer
- Institute for Electron Microscopy and Fine Structure Research; Graz University of Technology; Steyrergasse 17 8010 Graz Austria
| | - Andreas Klug
- NanoTecCenter Weiz Forschungsgesellschaft mbH; Franz-Pichler-Straße 32 8160 Weiz Austria
| | - Gregor Trimmel
- Christian Doppler Laboratory for Nanocomposite Solar Cells; Graz University of Technology and NanoTecCenter Weiz Forschungsgesellschaft mbH; Austria
- Institute for Chemistry and Technology of Materials; Graz University of Technology; Stremayrgasse 9 8010 Graz Austria
| | - Emil J. W. List
- NanoTecCenter Weiz Forschungsgesellschaft mbH; Franz-Pichler-Straße 32 8160 Weiz Austria
- Institute of Solid State Physics; Graz University of Technology; Petersgasse 16 8010 Graz Austria
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Beaupré S, Leclerc M. PCDTBT: en route for low cost plastic solar cells. JOURNAL OF MATERIALS CHEMISTRY A 2013; 1:11097. [DOI: 10.1039/c3ta12420g] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
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Garcia A, Welch GC, Ratcliff EL, Ginley DS, Bazan GC, Olson DC. Improvement of interfacial contacts for new small-molecule bulk-heterojunction organic photovoltaics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 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] [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%.
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Affiliation(s)
- Andres Garcia
- National Center for Photovoltaics, National Renewable Energy Laboratory, Golden, CO 80401, USA
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Cho S, Seo JH, Kim GH, Kim JY, Woo HY. Observation of ambipolar field-effect behavior in donor–acceptor conjugated copolymers. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c2jm34872a] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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