We recently described broadband white-light emission from layered lead-halide perovskites. When excited by UV light, these bulk solids emit across the entire visible spectrum, approximating sunlight. These hybrid phosphors have high color rendering indices (accurately representing illuminated colors) and tunable chromaticity coordinates, where halide substitution affords both 'warm' and 'cold' white light. They are promising as phosphors for solid-state lighting (SSL). The transition to SSL has been projected to halve the electricity consumption for lighting. However, current SSL devices require multiple light-emitting diodes and phosphors to create broadband white light. A single material that emits continuously from 400 to 700 nm is a major target in this field.<br/><br/>Most inorganic phosphors contain emissive dopants or surface sites. I will share our understanding of how a bulk material, with no obvious emissive sites, can emit every color of visible light. We proposed that the broad emission stems from excited electron-hole pairs (or excitons) that couple strongly to the lattice, thereby forming <i>transient</i> lattice defects. Importantly, although we attribute the broad emission to these 'excited-state defects', it responds to systematic variation in the inorganic sublattice, allowing synthetic control over the emission. I will explain synthetic design rules we have uncovered for obtaining white light from layered perovskites. The understanding we have developed of perovskite white-light emitters can be applied to other low-dimensional systems. I will also describe other inorganic topologies that afford broadband emission with a large Stokes shift.

Obtaining white light from layered perovskites

255th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.