Improving the performance of DSSCs by modulating the electron donor and electron acceptor of dye molecules with the DTPBT group as π-bridge

Abstract

When searching for abundant and economically viable green energy sources is a pressing task of our time, the study of dye-sensitized solar cells (DSSCs) as a photovoltaic conversion device is particularly important. Thus, to improve the performance of dye molecules with large planar dithienopyrrolobenzothiadiazole (DTPBT) as a π-bridge, the electron donor (D) and electron acceptor (A) of the H1 molecule were replaced with phenanthroimidazole and rhodanine 3-acetic acid, respectively, resulting in the new molecules Q1 and Q2. The photovoltaic properties of all molecules were investigated comprehensively, and the photoelectric conversion efficiency (PCE) of DSSCs based on these dyes was predicted using a rational model. The results show that rhodanine 3-acetic acid as the A of the Q2 increased the light-trapping ability of the dye molecule. And the Q2 has a unidirectional charge transfer excitation characteristic, which is favourable for generating effective photocurrents. Also, we predict a PCE of 6.15% for DSSCs based on the Q2, which is higher than the 4.73% (H1). Therefore, for using large DTPBT groups as π-bridges of molecules, suitable A will be more favourable for electron transfer and overall performance improvement, and the group’s potential can be more easily demonstrated.