Progress of organic photovoltaic cells based on squaraine small molecule donors and fullerene acceptors

Abstract

Squaraine (SQ) small molecules have been considered as efficient photoactive materials for organic photovoltaic (OPV) cells due to their simple synthetic routes, high absorption coefficients with tunable bandgaps and bandwidths in the visible-near infrared region, as well as high photochemical and thermal stabilities. The SQ donor and fullerene acceptor based OPV devices have realized the power conversion efficiencies of over 8%. In this paper, the progress of SQ donor and fullerene acceptor based OPV cells is reviewed, the effect of molecular structure, molecular aggregation and film morphology on the device performance is systematically summarized. The applied field of SQ donors in OPV cells is widened, and some proposals for future study are also given.