Charge transport through molecular ensembles: Triphenylamine-based organic dyes

Abstract

Based on the recently synthesized triphenylamine-based organic dyes [https://doi.org/10.1021/acsami.1c11547], several small molecules that can be considered as organic semiconducting materials in photovoltaic devices were theoretically modeled. It is found that these designed dyes with the donor-π conjugated bridge-acceptor (D-π-A) framework show high charge transport properties in the dye-synthesized solar cells (DSSCs). Divers types of π-bridges are explored and the structural, electronic, optical, and charge transport characteristics of considered organic small molecules are studied. Our results revealed the effect of π-bridge in tuning the charge transport properties of the studied dyes. Especially, it is found that the thiazole-based moieties as the most favorable candidate for π-bridges, can be used in the D-π-A backbone of the synthesized dye to improve the photovoltaic performance of the organic semiconductors. For designed organic dyes, the low electron reorganization energies and high intra-molecular coupling created by π-stacking give rise to improved electron and hole mobilities. This approach can be used for improving the semiconducting character of organic dyes in photovoltaic devices.