Electrochemically n-Doped CsPbBr₃ Nanocrystal Thin Films

Electrochemical doping is a promising strategy to dope halide perovskites without introducing impurities into the lattice. However, n-type doping of halide perovskites remains challenging due to intrinsically limited electrochemical stability. Herein, we report electrochemically n-doped CsPbBr₃ nanocrystal (NC) films within electrochemically stable potential windows (−0.9–0.5 V vs Ag/AgNO₃). Compared to bulk films with limited accessible surface area for cation charge compensation, NC films show more efficient n-doping properties due to their porous nature. Electrochemically doped NC films exhibit Fermi level shifts, confirmed via electrochemical measurements, vacuum-Kelvin probe contact potential difference, and photoelectron spectroscopy. As a result, in situ conductivity measurements show increases when films are p- or n-doped. Furthermore, n-doped films show a photoluminescence intensity increase. Given that we remain within the electrochemically stable window, we suspect this is due to an alleviation of electron traps, likely a result of altering the charge state of the interstitial Br population.