Effects of electron-withdrawing group and electron-donating core combinations on physical properties and photovoltaic performance in D-pi-A star-shaped small moleculesLuponosov, 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.
Research output: Contribution to journal › Article › Academic › peer-review
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.
|Number of pages||12|
|Publication status||Published - May-2016|
- 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