Glass Transition of Chiral Hybrid Metal Halides for Self‐Supported 3D Printing

ABSTRACT Hybrid metal halides (HMHs) have emerged as promising functional materials owing to their versatile structural tunability and outstanding optoelectronic properties. In particular, chiral HMHs could be endowed with fascinating chiroptoelectronic properties such as circularly polarized light emission, circularly polarized photodetection, and spin regulation. However, the implementation of their practical integrated optoelectronic applications has been mainly restricted to planar thin‐film devices due to the poor processability of chiral HMHs for the construction of complex three‐dimensional (3D) architectures. Here, we take advantage of the glass transition of chiral HMH with 3D printing technology to construct self‐supported 3D architectures with high‐performance linear and nonlinear optical functionalities. Chiral HMH ( R / S ‐THNA) 3 SbCl 6 ·0.5H 2 O ( R / S ‐THNA = R / S ‐1,2,3,4‐tetrahydro‐1‐naphthylammonium) forms transparent amorphous glass upon rapid quenching from its molten state. The resulting R / S ‐SbCl‐glass favors tunable photoluminescence colors and a large, continuously tunable range of glass transition temperature (∼50°C) through metal halide infusion. The intrinsic thermoplasticity of HMH glasses allows for additive‐free, thermally assisted extrusion‐based printing of self‐supporting 3D architectures. Upon recrystallization, the printed structures recovered non‐centrosymmetric crystal lattices and exhibited strong isotropic second harmonic generation response, enabling customized nonlinear optical imaging. This work establishes a thermally programmable paradigm for transforming HMHs from molecularly designed materials into 3D optical architectures.