Dopant and Compositional Modulation Triggered Broadband and Tunable Near-Infrared Emission in Cs₂Ag_1–<i>x</i>Na_<i>x</i>InCl₆:Cr³⁺ Nanocrystals

Abstract

Lead-free halide perovskite nanocrystals (NCs) have attracted more attention and demonstrated versatile potential in optoelectronic applications. However, achieving broadband near-infrared (NIR) emission in such materials remains a challenge. Herein, we successfully obtained Cr3+-doped Cs2AgInCl6 NCs via hot-injection synthesis, which exhibits a NIR emission with a large full width at half-maximum of 193 nm. Furthermore, tunable emission from 998 to 958 nm along with an enhanced photoluminescence quantum yield of 19.7% is realized by gradually substituting Ag+ with Na+, and the blue shift luminescence behavior is attributed to a strengthened crystal field around Cr3+. The excellent chemical and moisture stability together with the as-fabricated Cs2NaInCl6:Cr3+ NC film made by screen printing showcases its application potential in high-resolution images and NIR fluorescent signs. This work proves the possibility of realizing tunable broadband NIR emission in lead-free perovskite NCs and provides guidance for expanding their application in the NIR region.