Enhanced performance of dye-sensitized solar cells with Y-shaped organic dyes containing di-anchoring groups.

Two new Y-shaped D–π–(A)2 type phenothiazine-based dyes (ZJA2 and ZJA3) were designed and synthesized for dye-sensitized solar cells (DSSCs). Compared to the single D–π–A analogue dye ZJA1, the Y-shaped dye with two carboxylic acid anchors was in favour of enhancing the performance of DSSCs. The FTIR spectra revealed that the dye ZJA2 molecules were anchored onto the TiO2 surface by two carboxylic acid anchors, which effectively increased the electron extraction channels. The steady-state emission spectra and time-resolved fluorescence experiments all indicated that the electron injection efficiency of dye ZJA2 was improved by the increased electron extraction channels, thus the Jsc of ZJA2 was greatly improved compared to dye ZJA1. In addition, benzene was used as the π-bridge for linking di-anchoring groups, combined with CDCA, thereby reducing the charge recombination. As a result, the PCE of the DSSC based on ZJA2 (4.55%) was 67% higher than the DSSC based on ZJA1 (2.72%). The Y-shaped D–π–(A)2 type phenothiazine-based dye ZJA3 containing two pyridine anchors was also investigated, and the DSSC based on ZJA3 showed a poor PCE (0.45%) due to the low dye loading. [ABSTRACT FROM AUTHOR]