High-efficiency tunable self-trapped exciton emission in one-dimensional β-Cs3Cu2Br5via Ag alloying for optoelectronic applications

Abstract

Low-dimensional lead-free metal halides with efficient self-trapped exciton (STE) emission have attracted tremendous attention in lighting applications. Despite great efforts in manipulating the STE emission properties, it is still a great challenge to achieve controllable STE emission tuning. Herein, we successfully synthesized novel one-dimensional (1D) β-Cs₃Cu₂Br₅ with tunable emission color modulation from blue-greenish to yellow by alloying with different Ag contents. In particular, the sample with a ratio of 12.4% exhibits broadband emission peaking at 508 nm with a high quantum yield of ca. 100%. Temperature-dependent single crystal X-ray diffraction, photoluminescence, and femtosecond transient absorption (TA) measurements further reveal that the Ag-induced lattice distortion of β-Cs₃Cu₂Br₅ contributed to its controllable STE emission properties. Moreover, stable Ag-alloyed crystals have shown potential application prospects in encryption, radiation thermometry and solid-state light emitting devices. This lattice distortion tuning strategy provides a new vision for the controllable STE emission of low-dimensional metal halides.