Organic Electron\nAcceptors for FAPbI<sub>3</sub> Perovskites\nin Solutions and Solar Cells

Lead\nhalide perovskite-based electron transfer systems are transforming\nphotovoltaic and electrooptical (LED) technologies. Photoinduced interfacial\nelectron transfer (PIET) kinetics in such systems is crucial for charge\nseparation and the performance of perovskite solar cells (PSCs) and\nLEDs. Using time-resolved photoluminescence spectroscopic and electrochemical\nmeasurements, we validate PIET from FAPbI<sub>3</sub> perovskite quantum\ndots, nanocrystals, and thin films to strong electron transport layer\nmaterials such as tetracyanoquinodimethane or tetracyanobenzene. Successfully,\nwe constructed perovskite solar cells using quantum dots, nanocrystals,\nand polycrystalline thin films and validated the electron transfer\nrates and efficiencies. On the one side, the free energy changes (ΔGet0=\n−0.79 and −0.98 eV) obtained\nfrom electrochemical studies predict the PIET feasibility, whereas,\non the other side, TRPL data disclose the dynamic and static nature\nof PIET. Further, PSCs constructed using FAPbI<sub>3</sub> as the\ndonor and the above acceptors on TiO<sub>2</sub> electrodes demonstrate\nan increased power conversion efficiency with >70% fill factor\nand\na linear response to the incident power density.