Angewandte Chemie., 2019, 58(51), 18670-18675. https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.201911419

Very little is known about the realm of solid-state metal halide compounds comprising two or more halometalate anions. Such compounds would be of great interest if their optical and electronic properties could be rationally designed. Herein, we report a new example of metal halide cluster-assembled compound (C₉NH₂₀)₉[Pb₃Br₁₁](MnBr₄)₂, featuring distinctly different anionic polyhedra, namely, a rare lead halide cluster [Pb₃Br₁₁]⁵⁻ and [MnBr₄]²⁻. In accordance with its multinary zero-dimensional (0D) structure, this compound is found to contain two distinct emission centers, 565 nm and 528 nm, resulting from the formation of self-trapped excitons and ⁴T₁–⁶A₁ transition of Mn²⁺ ions, respectively. Based on the high durability of (C₉NH₂₀)₉[Pb₃Br₁₁](MnBr₄)₂ upon light and heat, as well as high photoluminescence quantum yield (PLQY) of 49.8 % under 450 nm blue light excitation, white light-emitting diodes (WLEDs) are fabricated, showcasing its potential in backlight application.

Adv. Opt. Mater., 2019, 7(24), 1901335. https://onlinelibrary.wiley.com/doi/abs/10.1002/adom.201901335

With single-component photoinduced white-light (WL) emission, low-dimensional hybrid halide perovskites have emerged as a new generation of luminescent materials; however, the effect of halogens on the intrinsic light emissions and the corresponding mechanisms is still unknown. Herein, the investigation of a family of two-dimensional (2D) hybrid perovskites R₂PbBr_4−xCl_x (R = BA⁺, PMA⁺, PEA⁺; x = 0, 1, 2, 3, 4) highlights the influence of halogens on intrinsic emission to reveal the dependence of the photoluminescence on the nature and contribution of the halogens. Ultrabroad emissions covering the entire visible-light region are achieved in the halogen hybrid systems with the stoichiometry of R₂PbBr₂Cl₂ (R = BA⁺, PMA⁺, PEA⁺), showing their potential as single-component WL phosphors in solid-state lighting devices. The origin of the WL emissions is the synergistic recombination emission of free excitons and self-trapped excitons. The ratio of halogens (Br/Cl) is confirmed to be a critical factor to fine-tune the intrinsic emission properties. This work provides a feasible strategy to achieve single-component WL emission in 2D hybrid perovskites, and proposes a method for regulating halogen contents for optimizing luminescent properties.

J. Phys. Chem. Lett. 2019, 10, 6, 1337–1341 https://pubs.acs.org/doi/abs/10.1021/acs.jpclett.9b00238

The understanding of broad-band emission mechanisms on low-dimensional metal halides is an urgent need for the design principle of these materials and their photoluminescence tuning. Herein, a new zero-dimensional (0D) organic–inorganic hybrid material (C₉NH₂₀)₆Pb₃Br₁₂ has been discovered, in which face-sharing PbBr₆ trimer clusters crystallize with organic cations (C₉NH₂₀⁺), forming periodic structure with 0D blocks. Broad-band green emission peaking at about 522 nm was observed for this material, with a full width at half-maximum (fwhm) of 134 nm. The emission was attributed to excitons trapped at controlled intrinsic vacancies, and this is the new example in 0D metal halides, also confirmed by spectroscopy analysis and first-principles calculations. Discovery of the single-crystalline hybrid material and observation of defect-induced luminescence extend the scope of bulk 0D materials and understanding of photophysical properties for optoelectronic applications.