Comparative study on N,N-di-p-tolylaniline-based D-π-A1-π-A2 sensitizers by tuning the auxiliary acceptor for dye-sensitized solar cells

We report the synthesis and DSSCs performance of two dye sensitizers XD1 and XD2 with D-pi-A1-pi-A2 structure bearing difluorobenzo[c][1,2,5]thiadiazole (DFBT) and diketopyrrolopyrrole (DPP)-based as auxiliary acceptor moieties. The effect of DFBT or DPP on the photophysical, electrochemical, and photovoltaic properties of the target dyes were investigated. It is found that DPP-containing XD2 achieve higher J(sc) result from its wider absorption spectrum ranging from visible to near-infrared region, higher molar absorption coefficient in the low-energy region and stronger photocurrent generation as compared to the DFBT-containing XD1. Additionally, the longer electron lifetime and increased charge recombination resistance of XD1 make it achieves higher V-oc. The photovoltaic properties of the DSSCs are synthetically influenced by J(sc) and V-oc. Eventually, the investigation of photovoltaic performance of DSSCs indicates that XD1 obtains slightly higher power conversion efficiency (PCE) of 5.04%, but the PCE of the DSSCs based on the dye XD2 with 1 mM CDCA as co-adsorbent is increased to 6.14%. (C) 2017 Elsevier Ltd. All rights reserved.