Low-dimensional hybrid metal halides are emerging as a highly promising class of single-component white-emitting materials for their unique broadband emission from self-trapped excitons (STEs). Despite substantial progress in the development of these metal halides, many challenges remain to be addressed to obtain a better fundamental understanding of the structure–property relationship and realize the full potentials of this class of materials. Here, via pressure regulation, a near 100% photoluminescence quantum yield (PLQY) of broadband emission is achieved in a corrugated 1D hybrid metal halide C5N2H16Pb2Br6, which possesses a highly distorted structure with an initial PLQY of 10%. Compression reduces the overlap between STE states and ground state, leading to a suppressed phonon-assisted non-radiative decay. The PL evolution is systematically demonstrated to be controlled by the pressure-regulated exciton–phonon coupling which can be quantified using Huang–Rhys factor S. Detailed studies of the S-PLQY relation for a series of 1D hybrid metal halides (C5N2H16Pb2Br6, C4N2H14PbBr4, C6N2H16PbBr4, and (C6N2H16)3Pb2Br10) reveal a quantitative structure–property relationship that regulating S factor toward 28 leads to the maximum emission.

Luo, H.Guo, S.Zhang, Y.Bu, K.Lin, H.Wang, Y.Yin, Y.Zhang, D.Jin, S.Zhang, W.Yang, W.Ma, B.Lü, X.Regulating Exciton–Phonon Coupling to Achieve a Near-Unity Photoluminescence Quantum Yield in One-Dimensional Hybrid Metal HalidesAdv. Sci. 2021, 2100786. abstract