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Effects of electron-withdrawing group and electron-donating core combinations on physical properties and photovoltaic performance in D-pi-A star-shaped small molecules

Luponosov, Y. N., Min, J., Solodukhin, A. N., Kozlov, O. V., Obrezkova, M. A., Peregudova, S. M., Ameri, T., Chvalun, S. N., Pshenichnikov, M. S., Brabec, C. J. & Ponomarenko, S. A., May-2016, In : Organic Electronics. 32, p. 157-168 12 p.

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  • Effects of electron-withdrawing group and electron-donating core

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DOI

  • Yuriy N. Luponosov
  • Jie Min
  • Alexander N. Solodukhin
  • Oleg V. Kozlov
  • Marina A. Obrezkova
  • Svetlana M. Peregudova
  • Tayebeh Ameri
  • Sergei N. Chvalun
  • Maxim S. Pshenichnikov
  • Christoph J. Brabec
  • Sergei A. Ponomarenko

The first representatives of star-shaped molecules having 3-alkylrhodanine (alkyl-Rh) electron-withdrawing groups, linked through bithiophene pi-spacer with electron-donating either triphenylamine (TPA) or tris(2-methoxyphenyl)amine (m-TPA) core were synthesized. The physical properties and photovoltaic performance of these novel molecules with 3-ethylrhodanine groups were comprehensively studied and compared to their full analogs having dicyanovinyl (DCV) units as the other type of well-known and frequently used acceptor groups. On one hand, the former demonstrate several advantages such as higher solubility and better photovoltaic performance in bulk-heterojunction (BHJ) organics solar cells (OSCs) as compared to the latter. Nevertheless, the former have slightly lower optical/electrochemical bandgaps and higher thermooxidation stability. On the other hand, molecules of both series based on m-TPA core along with higher solubility and higher position of HOMO energy levels have more pronounced tendency to crystalize as compared to the TPA-based molecules. Detailed investigation of the structure-property relationships for these series of molecules revealed that donor and acceptor unit combinations influence both charge generation and charge transport/recombination properties, as demonstrated by the ultrafast photoinduced absorption spectroscopy, space charge limited current measurements and transient photovoltage technique. These results give more insight how to fine-tune and predict physical properties and photovoltaic performance of small molecules having either alkyl-Rh or DCV units in their chemical structures and thus providing a molecular design guideline for the next generation of high-performance photovoltaic materials. (C) 2016 Elsevier B.V. All rights reserved.

Original languageEnglish
Pages (from-to)157-168
Number of pages12
JournalOrganic Electronics
Volume32
Publication statusPublished - May-2016

    Keywords

  • Star-shaped molecules, 3-Ethylrhodanine, Triphenylamine, Dicyanovinyl, Organic solar cells, Ultrafast charge separation, ORGANIC SOLAR-CELLS, POWER CONVERSION EFFICIENCY, INTERNAL CHARGE-TRANSFER, OPEN-CIRCUIT VOLTAGE, TRIAZINE CORE, SEMICONDUCTORS, OLIGOMERS, CHROMOPHORES, SUBSTITUTION, LIFETIME

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