Phase-Stable and Highly Luminescent CsPbI3 Perovskite Nanocrystals with Suppressed Photoluminescence Blinking.

Abstract

Despite their low band gap, the utility of CsPbI3 nanocrystals (NCs) in solar photovoltaic and optoelectronic applications is rather limited because of their phase instability and photoluminescence (PL) intermittency. Herein we show that phase-pure, monodispersed, stable and highly luminescent CsPbI3 NCs can be obtained by tweaking the conventional hot-injection method employing NH4I as an additional precursor. Single-particle studies show a significant suppression of PL blinking. Among all NCs studied, 60% exhibit only high-intensity ON states with a narrow distribution of intensity. The remaining 40% of NCs exhibit a much wider distribution of PL intensity with a significant contribution of low-intensity OFF states. Excellent characteristics of these CsPbI3 NCs are shown to be the result of NH4+ replacing some surface Cs+ of an iodide-rich surface of the NCs. These phase-stable and highly luminescent CsPbI3 NCs with significantly suppressed PL blinking can be useful single-photon emitters and promising materials for optoelectronic and solar photovoltaic applications.