Dual self-trapped excitons in 0D (TPA)₂Cu₄Br₆ for highly efficient long wavelength emission

TY - JOUR

T1 - Dual self-trapped excitons in 0D (TPA)2Cu4Br6 for highly efficient long wavelength emission

AU - Zheng, Kun

AU - Mi, Yanlin

AU - Wang, Wenyu

AU - Fu, Jianhui

AU - Khoo, Khoong Hong

AU - Liu, Yun

AU - Chen, Bingkun

AU - Cao, Jie

AU - Tan, Zhi Kuang

N1 - Publisher Copyright: © 2026 Elsevier B.V.

PY - 2026/5/5

Y1 - 2026/5/5

N2 - Zero-dimensional (0D) copper-based metal halides have emerged as promising candidates for efficient broadband emitters due to their strong electron-phonon coupling. Herein, we report an orange-emissive organic-inorganic hybrid copper bromide, (TPA)2Cu4Br6, which achieves an exceptional photoluminescence quantum yield (PLQY) of 94.26%. The single-crystal structural analysis, combined with detailed photophysical characterization, reveals the coexistence of two distinct self-trapped states closely associated with two possible distorted configurations of the [Cu4Br6]2- cluster, which serve as the structural basis for the formation of dual self-trapped excitons (STEs). Temperature-dependent characterization further elucidates the dynamic equilibrium between the two trapped states, providing mechanistic insights into the dual broadband emission behavior. Theoretical calculations suggest that the STEs arise from significant lattice distortion induced by the strong contraction of the Cu-Cu bond upon photoexcitation. Notably, the relatively low energy barrier for such distortion in copper-based lead-free halides favorably facilitates the formation of STE states. This work highlights the dual self-trapping mechanism in 0D copper halides and offers significant insights into designing long wavelength efficient broadband emitters for advanced optoelectronic applications.

AB - Zero-dimensional (0D) copper-based metal halides have emerged as promising candidates for efficient broadband emitters due to their strong electron-phonon coupling. Herein, we report an orange-emissive organic-inorganic hybrid copper bromide, (TPA)2Cu4Br6, which achieves an exceptional photoluminescence quantum yield (PLQY) of 94.26%. The single-crystal structural analysis, combined with detailed photophysical characterization, reveals the coexistence of two distinct self-trapped states closely associated with two possible distorted configurations of the [Cu4Br6]2- cluster, which serve as the structural basis for the formation of dual self-trapped excitons (STEs). Temperature-dependent characterization further elucidates the dynamic equilibrium between the two trapped states, providing mechanistic insights into the dual broadband emission behavior. Theoretical calculations suggest that the STEs arise from significant lattice distortion induced by the strong contraction of the Cu-Cu bond upon photoexcitation. Notably, the relatively low energy barrier for such distortion in copper-based lead-free halides favorably facilitates the formation of STE states. This work highlights the dual self-trapping mechanism in 0D copper halides and offers significant insights into designing long wavelength efficient broadband emitters for advanced optoelectronic applications.

KW - Broadband emission

KW - Electron-phonon coupling

KW - Self-trapped excitons

KW - Zero-dimensional copper halides

UR - https://www.scopus.com/pages/publications/105035686216

U2 - 10.1016/j.jallcom.2026.187980

DO - 10.1016/j.jallcom.2026.187980

M3 - Article

AN - SCOPUS:105035686216

SN - 0925-8388

VL - 1065

JO - Journal of Alloys and Compounds

JF - Journal of Alloys and Compounds

M1 - 187980

ER -