Isomer-dependent performance of thin-film solar cells based on petroporphyrins

Abstract

Complexes of etioporphyrin with transition metal ions are abundant in fossil fuels (hence the term petroporphyrins); their isolation from crude material or by laboratory synthesis are well-known procedures. Nonetheless, there are few examples of practical applications of these available and stable materials. We report an attempt to systematically introduce five synthetic etioporhyrin (EtioP) complexes with copper and nickel into archetypal thin-film photovoltaic cells fabricated entirely by vacuum thermal evaporation. It is shown that EtioPs act as effective donors in a planar heterojunction, where another porphyrinoid molecule, hexachloro-subphthalocyanine boron chloride Cl6SubPc, is used as an acceptor. The efficiency of the devices is limited due to the narrow-band absorption by the D/A pair and, hence, insufficient photon capturing from the sunlight spectrum. No clear correlation of the device parameters with the position isomerism or frontier molecular orbital energies of EtioPs is found. Best photovoltaic performance is shown by the Cu-EtioP-II based devices.