Molecular engineering of two-dimensional hybrid perovskites with broadband emission for white light-emitting diodes

Two-dimensional (2D) hybrid perovskites exhibiting broadband light emission are attractive as down-converting phosphors in white light-emitting diodes (WLEDs). Despite active exploration of new members of this family of materials, fine-tuning of their emission through structural variation for realizing high color-rendering white light remains largely untapped. Here we report a series of (100)-oriented 2D perovskites whose structures are templated by the organic cations. By controlling the tilting of the inorganic octahedra, we were able to shift the broadband emission from blue to white. A photophysical study further suggests that the coexistence of self-trapped excitons and free excitons contributes to a double-peak broad emission, covering the entire visible spectrum. Using the broad-emitting perovskites as down-converting phosphors, we fabricated WLEDs with white-light emission having a correlated color temperature (CCT) of 6600 K and a high color rendering index (CRI, R_a) of 86.