Abstract
Lead-halide perovskites have emerged as promising materials for photovoltaic and optoelectronic applications. Their significantly anharmonic lattice motion, in contrast to conventional harmonic semiconductors, presents a conceptual challenge in understanding the genesis of their exceptional optoelectronic properties. Here we report a strongly temperature dependent luminescence Stokes shift in the electronic spectra of both hybrid and inorganic lead-bromide perovskite single crystals. This behavior stands in stark contrast to that exhibited by more conventional crystalline semiconductors. We correlate the electronic spectra with the anti-Stokes and Stokes Raman vibrational spectra. Dielectric solvation theories, originally developed for excited molecules dissolved in polar liquids, reproduce our experimental observations. Our approach, which invokes a classical Debye-like relaxation process, captures the dielectric response originating from the incipient anharmonicity of the LO phonon at about 20 meV (160 cm(-1)) in the lead-bromide framework. We reconcile this liquid-like model incorporating thermally-activated dielectric solvation with more standard solid-state theories of the emission Stokes shift in crystalline semiconductors.
| Original language | English |
|---|---|
| Article number | 1175 |
| Number of pages | 8 |
| Journal | Nature Communications |
| Volume | 10 |
| DOIs | |
| Publication status | Published - 12 Mar 2019 |
Funding
Y.G. and L.E.B. acknowledge financial support from the Keck Foundation. O.Y. acknowledges funding by the FP7 People program under the project Marie Curie Grant No. IOF-622653. D.R.R acknowledges support from the NSF (NSF-CHE 1464802). Funding for this research was provided by the Center for Precision Assembly of Superstratic and Superatomic Solids, an NSF MRSEC (Award Number DMR-1420634). L.E.B. thanks Vasili Perebinos for informative and insightful discussion. Contributions Y.G., O.Y. and L.E.B. conceived the project. T.D.H. synthesized the samples under the supervision of J.S.O. Y.G. and O.Y. carried out optical measurements and data analysis. Y.G. and D.R.R. carried out theoretical analysis and modeling. Y.G., O.Y., D.R.R. and L.E.B. wrote the manuscript. All authors discussed and contributed to the manuscript.
All Science Journal Classification (ASJC) codes
- General Chemistry
- General Biochemistry,Genetics and Molecular Biology
- General Physics and Astronomy