Improvement of dye-sensitized solar cells performance through introducing different heterocyclic groups to triarylamine dyes

Abstract

This paper focuses on the structure modification of triphenylamine dyes for efficient dye-sensitized solar cells (DSSCs). Three D–D–π–A dyes (TTR1–3), with triphenylamine moiety and its derivatives as the electron donor, thiophene ring as the π-bridge, and 2-(1,1-dicyanomethylene)rhodanine (DCRD) as the electron acceptor, were synthesized and fully characterized. Nanocrystalline TiO₂-based DSSCs were fabricated using these dyes to investigate the effect of different donor groups introduced into triphenylamine on their photovoltaic performances. The overall power conversion efficiency (PCE) of DSSCs based on TTR1–3 with chenodeoxycholic acid (CDCA) coadsorbant are 5.20%, 5.71% and 6.30%, respectively, compared to 6.62% achieved with N719. Introduced heterocyclic group with alkyl lain into triphenylamine decreased dye absorbed amount but significantly improved the value of the open circuit voltage (V_oc) and the short-circuit photocurrent (J_sc), which result from the fact that they can effectively suppress the charge recombination and prevent aggregation between adjacent molecules on TiO₂. We also researched the effect of sensitization for single dyes on their photovoltaic performances. The PCEs of DSSCs soaked for 32 h increase slightly compared to those of DSSCs soaked for 16 h, which result from the adsorption quantity on the TiO₂ surface. We found that, with soaking twice in 32 h, the J_sc and V_oc were both obviously improved compared with soaking once in 32 h. These results provide a new approach for enhancing the photovoltaic performances of DSSCs based on single dye.