Structure–property relationship of different electron donors: novel organic sensitizers based on fused dithienothiophene π-conjugated linker for high efficiency dye-sensitized solar cells

Three novel organic dyes, coded Ba-01–03, based on D–π–A building blocks were synthesized and characterized for dye-sensitized solar cells (DSCs) to study the influence of different electron donors on photocurrent and photovoltage. The electron donor of Ba-01 was based on N-methoxyphenylcarbazole and the electron donors for Ba-02 and Ba-03 were based on different indoline analogs. The photovoltaic performance of these sensitizers was characterized using incident-photon-to-current conversion efficiency (IPCE), photovoltage measurements, and total solar-to-electric conversion efficiency (η). It was shown that photovoltage of indoline donor based dye Ba-03 showed the highest efficiency of 6.38% compared to carbazole donor based dye of Ba-01. DFT calculations were proven to be an effective tool in the prediction of the vertical electronic excitation, charge separation, and photovoltage as it effectively predicted the delocalization and coefficient size of the HOMO and LUMO for Ba-01–03.