Proceedings of nanoGe Fall Meeting19 (NFM19)
Publication date: 18th July 2019
Organic-inorganic halide perovskite solar cells showed remarkable enhancement in power conversion efficiency from 3% to >24% within ten years since their inception. However, the degradation of the perovskite solar cells under ambient conditions remained a key challenge towards commercialization of the devices. Tremendous efforts have been made by the scientific community to address the degradation challenge but substantial improvement in the stability of the solar cell devices is not achieved to date.
We investigated in detail the role of interfacial oxygen stoichiometry on the performance of perovskite solar cells. PIN type inverted perovskite solar cell devices were fabricated with the device architecture of ITO/NiO/MAPbI/C60/WO3/Ag. Where NiO is used as the hole transport layer and C60 is used as electron transport layers with MAPbI absorber. The HTL and absorber layers were fabricated using cost-effective spin coating method and C60 was deposited through thermal evaporation. We investigated the role of interfacial oxygen stoichiometry between NiO and MAPbI layer. The oxygen stoichiometry was controlled through short annealing of NiO film in oxidizing and reducing atmospheres. We find that the oxygen-deficient surface of the NiO shows better performance in the solar cell device. We performed the degradation studies of the oxygen-rich and oxygen-deficient interfaces between the metal oxide and perovskite layers. We found that the oxygen-deficient surface also shows relatively stable performance of the device as compared to the oxygen-rich interface between NiO and perovskite over several months of degradation studies. The excess oxygen present at the interface contributes towards faster degradation of the solar cell devices.
We thank the Deutscher Akademischer Austauschdienst (DAAD) for financial support under the German-Pakistan bi-lateral framework (Project #57345608
and 57458981).