Influence of Different Molecular Design Strategies on Photovoltaic Properties of a Series of Triphenylamine-Based Organic Dyes for Dye-Sensitized Solar Cells: Insights from Theoretical Investigations

Dye-sensitized solar cells (DSSCs) are deemed to show tremendous potential in clean, efficient, and inexpensive solar-energy technology, and precise presentation on the solar-to-electricity nature of photosensitizers in DSSCs may be a feasible strategy for developing highly efficiency and stable solar cell devices. In this contribution, we have investigated several triphenylamine-based D–A−π–A photosensitizers by adopting different molecular design strategies such as the exchange of auxiliary acceptor and π-spacer positions, and the introduction of new auxiliary acceptor or π-spacer units. Their photoelectric parameters have been estimated by the sophisticated first-principles computations coupled with the reliable theoretical models. It is found that the resulting dye by switching the position of auxiliary acceptor and π-bridge obtains a higher power conversion efficiency of 12.94%, in comparison to that of its parent analogue exhibiting a lower efficiency of 7.42%. The involvement of more π-conjugated auxiliary acceptor induces a slight increase of the efficiency thus the corresponding dye showing an efficiency of 8.60%. Most importantly, the dye featuring the thieno[3,2-b]thiophene π-linker portion demonstrates best photoelectronic performance of 16.49% among all studied dyes. Therefore, the inclusion of new π-bridge group may be the best strategy for enhancing the photovoltaic properties of such organic dye systems.