Solid-phase grinding synthesis of lead-free Cs2Ag1−xNaxIn1−yBiyCl6 nanocrystals for efficient light emission

Abstract

In recent years, lead-free halide perovskites have been extensively studied due to the lead toxicity and poor stability of lead halide perovskites. Cs₂AgInCl₆ has shown great potential to replace lead halide perovskites in optoelectronic applications. However, the synthesis method for this perovskite requires high temperature, and the synthesis conditions are relatively harsh. In this work, a simple solid-phase grinding method was employed to prepare Na⁺ and Bi³⁺ doped perovskite Cs₂Ag_1−xNa_xIn_1−yBi_yCl₆ with systematic characterization of both the structure and optical performance. The experimental results showed that a photoluminescence quantum yield (PLQY) of 13.1% was achieved by breaking the parity-forbidden transition through 4% Bi³⁺ doping. Subsequently, the incorporation of 60% Na⁺ suppressed non-radiative transitions and increased the PLQY to 56.9%. The Cs₂Ag_0.4Na_0.6In_0.96Bi_0.04Cl₆ samples were encapsulated on ultraviolet (UV) LED chips to obtain warm-yellow LEDs with good performance, which shows their promise for applications in the LED field.