Synthesis and density functional theory study of novel coumarin-type dyes for dye sensitized solar cells

A series of novel coumarin-type dyes were synthesized with coumarin donor, π bridges containing benzene and cyanoacetic acid or rhodanine acetic acid acceptor. The light-harvesting capabilities and photovoltaic performance of these dyes were investigated systematically. Moreover, density functional theory study of these coumarin dyes was performed. Among these compounds, dye with phenylthiophene bridge exhibits obvious superiority on optical and photovoltaic properties when compared with those of benzene or biphenyl bridge. Dyes bearing cyanoacetic acid acceptor have higher IPCE value and hence display better photovoltaic performance than those with rhodanine acetic acid acceptor. Dye with phenylthiophene bridge and cyanoacetic acid acceptor shows the most efficient photoelectricity conversion efficiency and has the maximum η value of 3.62% (Voc = 660 mV, Jsc = 7.72 mA/cm2, ff = 0.71) under simulated AM 1.5 irradiation (100 mW/cm2).