Donor-free oligothiophene based dyes with di-anchor architecture for dye-sensitized solar cells

Abstract

Traditionally, metal free DSSCs are fabricated from sensitizers designed using a donor-pi-acceptor (D-π-A) architecture. More recently, non-conventional dyes without strong donor units have emerged and have provided competitive power conversion efficiencies (PCEs) with respect to their (D-π-A)-based counterparts. Here, we report the synthesis and DSSC fabrication of oligothiophene molecules featuring two anchoring groups that do not possess strong donor moieties and are able to adopt V- and U-shape conformations. PCEs of 3.70% were obtained with the smaller 5-thiophene dyes (5T2A, 5T2A-E) possessing higher PCEs than their larger 8-thiophene counterparts containing diacetylene units (8T4A, 8T4A-E). Comparison to the DSSC properties of the analogous linear dye 5T, indicates that the architecture and structure of this series of dyes are likely responsible for their lower performance. This journal is