Organic Electron Acceptors for FAPbI₃ Perovskites in Solutions and Solar Cells

Lead halide perovskite-based electron transfer systems are transforming photovoltaic and electrooptical (LED) technologies. Photoinduced interfacial electron transfer (PIET) kinetics in such systems is crucial for charge separation and the performance of perovskite solar cells (PSCs) and LEDs. Using time-resolved photoluminescence spectroscopic and electrochemical measurements, we validate PIET from FAPbI3 perovskite quantum dots, nanocrystals, and thin films to strong electron transport layer materials such as tetracyanoquinodimethane or tetracyanobenzene. Successfully, we constructed perovskite solar cells using quantum dots, nanocrystals, and polycrystalline thin films and validated the electron transfer rates and efficiencies. On the one side, the free energy changes (ΔGet0= −0.79 and −0.98 eV) obtained from electrochemical studies predict the PIET feasibility, whereas, on the other side, TRPL data disclose the dynamic and static nature of PIET. Further, PSCs constructed using FAPbI3 as the donor and the above acceptors on TiO2 electrodes demonstrate an increased power conversion efficiency with >70% fill factor and a linear response to the incident power density.