Long-Range Interfacial Charge Carrier Trapping in Halide Perovskite-C60 and Halide Perovskite-TiO2 Donor-Acceptor Films

Interfacial electron transfer across perovskite-electron acceptor heterojunctions plays a significant role in the power-conversion efficiency of perovskite solar cells. Thus, electron donor-acceptor thin films of halide perovskite nanocrystals receive considerable attention. Nevertheless, understanding and optimizing distance- and thickness-dependent electron transfer in perovskite-electron acceptor heterojunctions are important. We reveal the distance-dependent and diffusion-controlled interfacial electron transfer across donor-acceptor heterojunction films formed by formamidinium or cesium lead bromide (FAPbBr(3)/CsPbBr3) perovskite nanocrystals with TiO2/C-60. Self-assembled nanocrystal films prepared from FAPbBr(3) show a longer photoluminescence lifetime than a solution, showing a long-range carrier migration. The acceptors quench the photoluminescence intensity but not the lifetime in a solution, revealing a static electron transfer. Conversely, the electron transfer in the films changes from dynamic to static by moving toward the donor-acceptor interface. While radiative recombination dominates the electron transfer at 800 mu m or farther, the acceptors scavenge the photogenerated carriers within 100 mu m. This research highlights the significance of interfacial electron transfer in perovskite films.

Automated summary

This study reveals the distance-dependent and diffusion-controlled interfacial electron transfer across perovskite-electron acceptor heterojunction films. Perovskite nanocrystals exhibit long-range carrier migration in self-assembled films, while acceptors quench photoluminescence intensity without affecting lifetime. The research underscores the importance of interfacial electron transfer in perovskite films.