Thienoisoindigo (TIIG)-based small molecules for the understanding of structure-property-device performance correlations

Abstract

In this contribution, a series of small molecule semiconductors based on the recently perceived thienoisoindigo (TIIG) and three different end-capping moieties benzene, naphthalene, and benzofuran with varied electron-donating strength and conformations has been synthesized by Suzuki coupling and utilized for organic photovoltaics (OPVs). Incorporation of different end-capping blocks into TIIG core facilitates the tuning of optical properties and the electronic structure (HOMO/LUMO energy levels), solid-state morphology, the performance in OPVs. In this study, a correlation between the molecular structure, thin film morphology, and photovoltaic properties of these conjugated small molecules is established that provides guidance for the molecular design of new photovoltaic semiconductors based on TIIG units.