Regulating Exciton–Phonon Coupling to Achieve a Near‐Unity Photoluminescence Quantum Yield in One‐Dimensional Hybrid Metal Halides

Abstract

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 C 5 N 2 H 16 Pb 2 Br 6 , 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

Pressure-Driven Reverse Intersystem Crossing: New Path toward Bright Deep-Blue Emission of Lead-Free Halide Double Perovskites

“…The analysis results of the theoretical calculation demonstrated that, at the low-pressure region, all octahedra exhibited a persistent shrinking, resulting in the continuous cell contraction. The reduction of exciton–phonon coupling strength can also be attributed to the shrinkage of octahedra upon compression, which strengthens the metal–halogen bond energy of and weakens the deformability of the lattice. − The attenuated electron–phonon coupling strength would decrease the STE bind energy owing to the detrapping of STEs. Eventually, the intensity of both NE and BE decreased under much higher pressure .…”

A One-Dimensional Broadband Emissive Hybrid Lead Iodide with Face-Sharing PbI6 Octahedral Chains

“…Broadband STE emissions of low-dimensional metal halides were first reported in 2D layered Pb–Cl and Pb–Br perovskites by Dohner et al in 2014, , largely triggering the boom of this sort of materials, while at that time the luminescence of analogous Pb–I slabs was commonly dominated by a narrowband free exciton (FE) emission. , Subsequently, it was found that STE and FE emissions can coexist in 1D or 2D lead iodides, − in which the former is usually weaker than the latter. ,, In contrast to 2D counterparts, 1D lead-based hybrid systems with unique core–shell quantum wire structures hold greater structural adjustability and tunable photoluminescence (PL) properties. − For instance, the corrugated 1D structure based on double-edge-shared octahedral PbBr 6 2– units , shows an initial PL quantum yield (PLQY) of 10%, which is significantly elevated to 100% at a pressure of 3 GPa . In addition, the 1D postperovskite type chains constructed by the corner-sharing dimers with edge-sharing PbX 6 (X = Cl, Br, and I) octahedra show tunable, broadband luminescence properties , and high PLQY (60%); in such a nice system, the nature of halogen significantly governs the intensity of the resulting broadband emission through tuning the excitonic self-trapping depth (Cl > Br > I) .…”

“…20,21,23 In contrast to 2D counterparts, 1D lead-based hybrid systems with unique core−shell quantum wire structures hold greater structural adjustability and tunable photoluminescence (PL) properties. 24−30 For instance, the corrugated 1D structure based on double-edge-shared octahedral PbBr 6 2− units 24,31 shows an initial PL quantum yield (PLQY) of 10%, which is significantly elevated to 100% at a pressure of 3 GPa. 31 In addition, the 1D postperovskite type chains constructed by the corner-sharing dimers with edge-sharing PbX 6 (X = Cl, Br, and I) octahedra show tunable, broadband luminescence properties 21,32 and high PLQY (60%); 33 in such a nice system, the nature of halogen significantly governs the intensity of the resulting broadband emission through tuning the excitonic self-trapping depth (Cl > Br > I).…”

“…24−30 For instance, the corrugated 1D structure based on double-edge-shared octahedral PbBr 6 2− units 24,31 shows an initial PL quantum yield (PLQY) of 10%, which is significantly elevated to 100% at a pressure of 3 GPa. 31 In addition, the 1D postperovskite type chains constructed by the corner-sharing dimers with edge-sharing PbX 6 (X = Cl, Br, and I) octahedra show tunable, broadband luminescence properties 21,32 and high PLQY (60%); 33 in such a nice system, the nature of halogen significantly governs the intensity of the resulting broadband emission through tuning the excitonic self-trapping depth (Cl > Br > I). 21 Moreover, the optical bandgap of metal halides increases with the increasing number of X ions shared with neighboring PbX 6 octahedra and follows the trend "facesharing > edge-sharing > corner-sharing".…”

Pressure-Enhanced Photocurrent in One-Dimensional SbSI via Lone-Pair Electron Reconfiguration

“…As an alternative thermodynamic parameter, pressure can effectively modify the local structure and coordination, and further achieve modification of LPEs [ 23 , 24 , 25 , 26 , 27 , 28 , 29 ]. In this work, by using high pressure to modulate the local structure of SbSI, the stereochemical role of LPEs is controllably manipulated towards designable optoelectronic properties.…”