Synthesis of Thermally Stable and Highly Luminescent Cs<sub>5</sub>Cu<sub>3</sub>Cl<sub>6</sub>I<sub>2</sub> Nanocrystals with Nonlinear Optical Response
Changhee Jang, Kangyong Kim, Hak‐Won Nho, Seung Min Lee, Hanif Mubarok, Joo Hyeong Han, Hyeonjung Kim, Dongryeol Lee, Yangpil Jang, Min Hyung Lee, Oh‐Hoon Kwon, Sang Kyu Kwak, Won Bin Im, Myoung Hoon Song, Jongnam Park
Abstract
Abstract Low‐dimensional Cu(I)‐based metal halide materials are gaining attention due to their low toxicity, high stability and unique luminescence mechanism, which is mediated by self‐trapped excitons (STEs). Among them, Cs 5 Cu 3 Cl 6 I 2 , which emits blue light, is a promising candidate for applications as a next‐generation blue‐emitting material. In this article, an optimized colloidal process to synthesize uniform Cs 5 Cu 3 Cl 6 I 2 nanocrystals (NCs) with a superior quantum yield (QY) is proposed. In addition, precise control of the synthesis parameters, enabling anisotropic growth and emission wavelength shifting is demonstrated. The synthesized Cs 5 Cu 3 Cl 6 I 2 NCs have an excellent photoluminescence (PL) retention rate, even at high temperature, and exhibit high stability over multiple heating–cooling cycles under ambient conditions. Moreover, under 850‐nm femtosecond laser irradiation, the NCs exhibit three‐photon absorption (3PA)‐induced PL, highlighting the possibility of utilizing their nonlinear optical properties. Such thermally stable and highly luminescent Cs 5 Cu 3 Cl 6 I 2 NCs with nonlinear optical properties overcome the limitations of conventional blue‐emitting nanomaterials. These findings provide insights into the mechanism of the colloidal synthesis of Cs 5 Cu 3 Cl 6 I 2 NCs and a foundation for further research.