Intermolecular Hydrogen-Bonding Correlated Structure Distortion and Broadband White-Light Emission in 5-Ammonium Valeric Acid Templated Lead Chloride Perovskites

Two-dimensional (2D) perovskite broadband emitters are gaining intensive attention in light-emitting fields. However, the limitation of structure distortion modulation hinders the increase of emission intensity, and the high toxicity of organic diamine causes potential damage to human health. Herein, we utilize a green organic spacer 5-ammonium valeric acid (Ava) to template novel 2D lead chloride hybrids, Ava2PbCl4, where intermolecular O1···H–O2 interactions form between the adjacent organic cation layers. The intermolecular hydrogen bonding in Ava2PbCl4 causes a larger cation penetration depth which enables larger structural deformation than the pentamethylenediammonium lead chloride (PDAPbCl4) reference. This octahedral deformation further leads to ultrabroadband emission in Ava2PbCl4, which achieves enhanced photoluminescence quantum yield (2.83%) compared to PDAPbCl4 (0.4%). Further mechanism investigation indicates that these broadband emissions could be assigned as the transient self-trapped excitons luminescence. Density functional theory calculation indicates that the octahedral distortions are traced to an electronic origin as well. The above findings reveal the key role of intermolecular hydrogen bonding in modulating the photophysical properties of 2D perovskites and will benefit the design of green perovskites for optoelectronic applications.