White Light-Emitting Diodes Based on One-Dimensional Organic–Inorganic Hybrid Metal Chloride with Dual Emission

White-light emissive organic-inorganic hybrid metal halides (MHs) have shown promising potential applications in solid-state lighting. As one-dimensional (1D) MHs for white-light emission remain rare and the key role of halogen regulation in 1D hybrid MHs for broadband emission (BE) has not been well established yet, herein, we report a family of 1D hybrid MHs TMGPbX3 (TMG = 1,1,3,3-tetramethylguanidine, X = Cl-, Br-, or I-) to systematically explore the influence of halogen on crystal structures and photoluminescence (PL) properties in 1D organic-inorganic hybrid MHs. Under ultraviolet excitation, TMGPbBr3 and TMGPbI3 exhibit BE originating from self-trapped excitons (STEs), while TMGPbCl3 manifests the special blue-white dual emission, which is contributed by STEs in inorganic frameworks and free excitons (FEs) in the organic component. Different emission mechanisms of three 1D MHs are well demonstrated and compared. With a PL quantum yield (PLQY) up to 11.67%, a white light-emitting diode (WLED) based on TMGPbCl3 was fabricated to show its valuable application in solid-state lighting.