Two Novel Two-Dimensional Organic-Inorganic Hybrid Lead Halides with Broadband Emission for White-Light-Emitting Diodes

Low-dimensional organic-inorganic metal halides (LOMHs) recently have attracted much attention due to their tunable crystal structures and excellent photoelectric properties. The configuration and arrangement of organic cations in LOMHs have significant effect on the structure of inorganic frameworks and luminescence properties. In this work, we systematically explored the "spatial effect" and "hydrogen bonding effect" of organic cations on the structure and properties of LOMHs, by synthesizing three LOMHs including (N-AD)PbCl₄, (N-AD)₂Pb₂Br_7, and (N-AD)₄Pb₃I₁₂ (N-AD: N-acetylethylenediamine, C₄H₁₀N₂O). Specifically, (110)-oriented two-dimensional (N-AD)PbCl₄ and (N-AD)₂Pb₂Br₇ with manifest blue-white emissions, originating from the free excitons (FEs) and self-trapped excitons (STEs), respectively. The UV-pumped light-emitting diode (LED)-based on (N-AD)₂Pb₂Br₇ was prepared, and the highest color rendering index (CRI) and correlated color temperature (CCT) were up to 80 and 4484 K, respectively. This proves its potential application in solid-state lighting.