Reliability Enhancement of Perovskite Solar Cells: Role of Low-Dimensional Materials for Interfacial Modifications

Abstract

Perovskite solar cells (PSCs) have drawn a great deal of attention in the photovoltaic community owing to their excellent power conversion efficiency and low-cost production. Interfaces remain the weakest part of the complete device, holding their further improvement towards commercialization. This thesis focuses on a comprehensive understanding of the photo-induced charge transfer dynamics and the reliability enhancement of PSCs based on interfacial modification through low-dimensional semiconductor materials. It is found that the two-dimensional (2D) transition metal dichalcogenides (TMDs)-based interfacial layer minimizes the energy barrier and charge accumulation at the interface of the perovskite/charge-transport-layer while prompting extraction of photo-induced charges in the device. The reduction of interface recombination and the enhancement of charge transfer dynamics at the NiOx nanocrystal/perovskite interface were further constructed by the application of a molecularly engineered dithieno thiophene-based thin organic semiconductor layer on NiOx. The developed strategy is further extended with the implementation of a 2D-C3N4 polymeric network, which enables greater PCE byreducing non-radiative losses and faulty charge build-up at the NiOx/perovskite interface. The greater stability of perovskite is established owing to the strong coordination of MA+ cations with unbound nitrogen electron pairs in the C3N4. A thorough grasp of the perovskite/electron transport layer interface was further studied, and it is found that 2D-TiS2 had a greater effect on PV performance when paired with PC60BM under ideal addition. The results presented in this thesis offer unique insight into the interfacial modification using low-dimensional materials to achieve simultaneous high efficiency and stability in PSCs.