Synthesis and organic photovoltaic (OPV) properties of triphenylamine derivatives based on a hexafluorocyclopentene “core”

A series of new “D-A-D” chromophores containing hexafluorocyclopentene thiophene as an acceptor and a triphenylamine unit as a donor, called TP-G1, TP-G2, TPB-G1 and TPB-G2, were designed and synthesized. Heterojunction organic photovoltaic (OPV) cells containing these chromophores were fabricated, and device 1, with the structure of ITO/PEDOT:PSS/TP-G1:P3HT/LiF/Al, displayed an open-circuit voltage (Voc), short-circuit current (Jsc) and power-conversion efficiency (η) of 0.74 V, 1.178 mA/cm2 and 0.22%, respectively. The triphenylamine group could effectively induce the open-ring isomer to close because the 4- and 4′- positions of the benzene rings were substituted by an electron-donating group and the value of the quantum yields of the closed-ring isomers increased. As a result, the closed-ring isomer facilitated intramolecular π-electron delocalization and exhibited a broad absorption band ranging from 200 to 850 nm. Due to the fluorine substitution of hexafluorocylopentene at the molecular center and the hole-transport characteristics of the triphenylamine moiety on the periphery, our chromophores showed obvious dual semiconductor properties, i.e., n- and p-type, which demonstrated a potential application for OPV devices.

Graphical AbstractThe open-ring isomer of hexafluorocyclopentene can be effectively closed by triphenylamine group to obtain both strong and broad absorption band ranging from 200 to 850 nm. Heterojunction organic photovoltaic (OPV) cell containing hexafluorocyclopentene derivative as an active layer displayed power-conversion efficiency (h) of 0.22%.Figure optionsDownload as PowerPoint slide