Mechanism of Enhanced Broadband Emission
Nov. 7, 2018
The lattice distortion promotes a self-trapped exciton that emits broadband white light with a very high efficiency.
We revealed that the origin of the broadband emission in Na-doped Cs2AgInCl6 double perovskite is due to the formation of a special self-trapped exciton (STE). Pure Cs2AgInCl6 exhibits poor broadband emission due to inversion symmetry-induced parity-forbidden transition. Na-incorporation breaks the parity-forbidden transition and turns on the emission. As a result, the broadband emission photoluminescence quantum yield (PLQY) increases dramatically as the Na concentration increases. We further found that there is an optimal Na concentration to maximize the PLQY, in agreement with experimental results.
Significance and Impact
Systems with efficient and stable white emission are ideal for lighting but fundamentally difficult to achieve. Our results provide insights and design criteria for new materials that can further improve broad emission efficiency.
- Cs2AgInCl6 exhibits poor broadband emission PLQY due to inversion symmetry-induced parity-forbidden transition.
- The PLQY can be dramatically improved via selected impurity-incorporation to break the parity-forbidden transition.
University of Toledo