Ring-protected small molecules for organic photovoltaics

Jianyuan Sun, Lianjie Zhang, Ashishi Dubey, Swaminathan Venkatesan, Ting Yu Lin, Logan Sanow, Yu Chueh Hung, Andrew Sykes, Hongshan He, Qiquan Qiao, Cheng Zhang

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Recently, excellent solar cell device performances have been achieved with solution-processed small-molecule donor materials. Small molecules have well defined structures and thus allow better control of self-assembly in the solid state. However, the easy formation of H-type aggregates and lack of strong interactions between nanodomains could limit charge transport, device performance, and long-term stability. We have recently explored the synthesis of ring-protected small molecules (with rings surrounding the center of the molecules), studied the intermolecular interactions in solution and solid state, and conducted preliminary solar cell device fabrications. It has been found that the molecules behave very differently from conventional flat small molecules in both solution and solid states. Proton NMR study of solutions of different concentrations revealed the presence of strong intermolecular interactions as a result of absence or shortage of open-ended alkyl side chains; however, such strong interactions do not lead to precipitation of the molecules even at high concentrations. Excellent films are routinely obtained from the neat small molecules despite the much reduced number of solubilizing groups. The New findings strongly suggest that ring protection is an effective strategy to avoid Haggregation and maintain strong pi-pi interactions simultaneously. Such materials are expected to form head-tail selfassemblies that will open new possibilities for small molecule organic materials. Conceptually, thin films of such materials are potentially more isotropic in charge transport than conventional small molecule and polymer films, a property desirable for photovoltaics and some other optoelectronic applications.

Original languageEnglish (US)
Title of host publicationOrganic Photovoltaics XIV
DOIs
StatePublished - 2013
Externally publishedYes
EventOrganic Photovoltaics XIV - San Diego, CA, United States
Duration: Aug 27 2013Aug 29 2013

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume8830
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X

Conference

ConferenceOrganic Photovoltaics XIV
CountryUnited States
CitySan Diego, CA
Period8/27/138/29/13

Keywords

  • Chromophore
  • Dimer formation
  • Herringbone
  • Hole mobility
  • Self-assembly
  • Single crystal
  • Small molecule
  • Solar cell
  • Time of flight

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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