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 -