π–π and p–π conjugation, which is more efficient for intermolecular charge transfer in starburst triarylamine donors of platinum acetylide sensitizers?

• Two novel platinum acetylide sensitizers were synthesized and applied in DSSCs.
• The introduction of π–π span group increased the donating and coplanar properties.
• New absorption peaks around 410 nm of dyes were found due to the conjugative effect.
• The span group in electron donors plays an important role for the design of sensitizers.

Two novel starburst donors based platinum acetylide sensitizers with π–π conjugated span group (2-vinylthiophene) were synthesized and applied in dye-sensitized solar cells (DSSCs). The photovoltaic performances of sensitizers were investigated by photophysical, photovoltaic, electrochemical, and a theoretical approach. Compared with similar triphenylamine based platinum acetylide sensitizers which do not contain a 2-vinylthiophene group, it was found that the introduction of 2-vinylthiophene as a span group increased the donating ability of donor and the coplanar property between the donor and π-bridge, which are in favour of the intramolecular charge transfer. Moreover, the new DSSCs based sensitizers displayed a power conversion efficiency of 2.80% and 2.95%, which is significantly improved over that determined for the non-vinylthiophene containing analogues.

Two novel starburst donor based platinum acetylide sensitizers with π–π conjugated span group (2-vinylthiophene) were synthesized and applied in dye-sensitized solar cells (DSSCs). This work demonstrated that the π–π span group in the electron donors plays a more important role in the sensitizers for the intermolecular charge transfer compared with p–π conjugation unit.Figure optionsDownload as PowerPoint slide