A comparison of the optical and photovoltaic properties of novel double branched organic dyes in dye sensitized solar cells

• The effect of unsymmetrical anchoring groups in organic DSSCs was extensively studied.
• Unsymmetrical dye showed improved IPCE and Jsc values compared to other dyes.
• EIS calculations indicate that unsymmetrical dye exhibit good charge transfer properties.
• Also showed better efficiency than the single, symmetrical and co-sensitizing system.

A novel efficient metal free sensitizer containing unsymmetrical double branched anchoring dye (AB) was synthesized for dye-sensitized solar cells (DSSCs) and compared with corresponding cosensitizer (A + B), single (A, B) and symmetric double branched (AA, BB) dyes. Comparing to 2.23% for the DSSC based on the dye with (A + B), 1.29% and 1.51% for the DSSCs based on the dyes with A, B and 2.03% and 2.02% for the DSSCs based on the dyes with AA, BB, the overall conversion efficiency reaches 2.43% for AB-sensitized solar cell as a result of its complementary absorption, more efficient interfacial charge generation and transport. The results show that the performance of DSSCs can be effectively enhanced by the cooperation of two different donor-acceptor containing branches in one molecule of the dye.