Molecular engineering towards efficientwhite-light-emitting perovskite

Low-dimensional hybrid perovskites have demonstrated excellent performance as white-light emitters. The broadband white emission originates from self-trapped excitons (STEs). Since the mechanism of STEs formation in perovskites is still not clear, preparing new low-dimensional white perovskites relies mostly on screening lots of intercalated organic molecules rather than rational design. Here, we report an atom-substituting strategy to trigger STEs formation in layered perovskites. Halogen-substituted phenyl molecules are applied to synthesize perovskite crystals. The halogen-substituents will withdraw electrons from the branched chain (-R-NH3+) of the phenyl molecule. This will result in positive charge accumulation on -R-NH3+, and thus stronger Coulomb force of bond (-R-NH3+)-(PbBr42-), which facilitates excitons self-trapping. Our designed white perovskites exhibit photoluminescence quantum yield of 32%, color-rendering index of near 90 and chromaticity coordinates close to standard white-light. Our joint experiment-theory study provides insights into the STEs formation in perovskites and will benefit tailoring white perovskites with boosting performance. Broad-band emission of self-trapped exciton in low-dimensional perovskite is prospective for white LED, yet rational design new white perovskite remains challenge. Here, the authors develop an atom-substituting strategy to trigger exciton self-tapping in perovskites and reveal the mechanism behind.

Automated summary

The article introduces a method of utilizing an atom-substituting strategy to trigger exciton self-trapping in layered perovskites, and demonstrates the excellent performance of the designed white perovskites.