Organic dyes containing fused acenes as building blocks: Optical, electrochemical and photovoltaic properties

Abstract Two D- π -A dyes based on fused acenes (carbazole, cyclopenta[2,1-b:3,4-b']dithiophene (CPDT) and dithieno[3,2-b:2',3'-d]pyrrole (DTP)) were synthesized, characterized using UV-vis absorption spectroscopy and electrochemistry, density function theory (DFT) calculations, and used as sensitizers in dye-sensitized solar cells (DSSCs). The two sensitizers were compared thoroughly over physicochemical properties and DSSC performance. Although the DTP dye has slightly blue-shifted and weaker incident photon-to-collected electron (IPCE) conversion efficiency responses, the much increased open-circuit photovoltage values and improved charge-transfer kinetics relative to the CPDT systems result in superior power conversion efficiencies. This work reveals the potential of DTP as a bridge in the design of sensitizers.