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

Y.N. Luponosov, J. Min, A.N. Solodukhin, O.V. Kozlov, M.A. Obrezkova, S.M. Peregudova, T. Ameri, S.N. Chvalun, M.S. Pshenichnikov, C.J. Brabec, S.A. Ponomarenko

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

The first representatives of star-shaped molecules having 3-alkylrhodanine (alkyl-Rh) electron-withdrawing groups, linked through bithiophene π-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. © 2016 Elsevier B.V. All rights reserved.
Original languageEnglish
Pages (from-to)157-168
Number of pages12
JournalOrganic Electronics
Volume32
DOIs
Publication statusPublished - 2016

Keywords / Materials (for Non-textual outputs)

  • Absorption spectroscopy
  • Electrons
  • Heterojunctions
  • Molecules
  • Organic solar cells
  • Photovoltaic effects
  • Solar power generation
  • Solubility
  • Stars
  • Synthesis (chemical)
  • Thermooxidation
  • 3-Ethylrhodanine
  • Charge separations
  • Dicyanovinyl
  • Star-shaped molecules
  • Triphenyl amines
  • Solar cells

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