Self-assembling discotic materials with low symmetry for organic photovoltaics

Three new discotic liquid crystalline (DLC) penta(phenylethynyl)benzene derivatives (HSC0X, X = 1-3) in nonchiral, homogeneously chiral, and racemic conformations were used as smart dopants between poly [[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][s-fluoro-2-[2-ethylhexyl]carbonyl] thirno[3,4-b]thiophene- diyl]](PTB7) and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) which can achieve one-dimensional (1D) charge transportation for organic solar cells (OSCs). All HSC0X exhibits columnar rectangular phase stability over a reasonably broad temperature and is characterized by powder X-ray analysis and polarized optical microscopy (POM). The thermal imaging revealed the best homogeneity of heat distribution for devices PTB7:PC71BM:HSC0X ternary active layer with resistance value 26.4-53.5 X. The resulting power conversion efficiency (PCE) values were strongly dependent on the molecular conformation and specific amount of the dopants in an active layer. A narrow band gap at 1.01 eV was found for the nonchiral discotic material (HSC01) as well as a low-lying highest occupied molecular orbital (HOMO) energy level of ti -5.34 eV and the best PCE of 3.02%. (c) 2022 Elsevier B.V. All rights reserved.

Automated summary

Three new discotic liquid crystalline compounds were used as smart dopants in organic solar cells to achieve one-dimensional charge transportation. The power conversion efficiency of the cells was found to be strongly influenced by the molecular conformation and specific amount of dopants in the active layer.