Structure and absorption in C60–zinc tetra-phenylporphyrin composite materials: A computational study

Abstract

We investigate structure and photo-excitation in C60-zinc tetraphenylporphyrin (ZnTPP) and C60F48-ZnTPP complexes, which are promising candidates for organic photovoltaic devices. The C60-ZnTPP complex results from π-π stacking between the fullerene and porphyrin structures, and has a binding energy of 76.0 kJ/mol. Fluorination of the C60 cage leads to decrease in ZnTPP binding, due to reduced π−π stacking interaction. C60-ZnTPP photoexcitation results largely from internal ZnTPP π → π* transitions, although delocalised ZnTPP π → C60 π* transitions are also observed below 300 nm. The more intense photoexcitations of C60F48-ZnTPP arise solely from localised ZnTPP π → π* transitions.