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Published on: February 27, 2017
Strain Relaxation on Perovskite Surface via Light-Enhanced Ionic Homogeneity
Yujie Wang1, Jinzhao Li2, Huanqi Cao1
1Key Laboratory of Display Materials and Photoelectric Devices (Ministry of Education), Tianjin Key Laboratory for Photoelectric Materials and Devices, and National Demonstration Center for Experimental Function Materials Education, School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384, P. R. China.
Light illumination, especially short wavelengths, reduces strain in perovskite solar cells (PSCs) by promoting ionic diffusion. This strain relaxation enhances PSC efficiency and stability by reducing charge traps.
Area of Science:
- Materials Science
- Renewable Energy
- Solid-State Physics
Background:
- Strain at interfaces significantly impacts perovskite solar cell (PSC) performance.
- External conditions, particularly light, influence interfacial strain.
- Understanding light's effect on strain is crucial for improving PSCs.
Purpose of the Study:
- Investigate vertical strain distribution in perovskite films under varied light wavelengths.
- Elucidate the mechanism of light-induced strain relaxation.
- Correlate strain changes with PSC efficiency and stability.
Main Methods:
- Perovskite films synthesized using formamidinium iodide (FAI)/methylammonium chloride (MACl) vapor and PbI2 (CsBr) films.
- Incident-angle-dependent grazing-incidence wide-angle X-ray scattering (GIXAS) for strain evaluation.
- Analysis of ionic diffusion under different light wavelengths.
Main Results:
- Perovskite films exhibited out-of-plane compressive and in-plane tensile strains, concentrated at the surface.
- Short-wavelength light induced vertical ionic homogeneity by promoting diffusion of FA, MA, Cs, and I ions.
- Strain relaxation on the perovskite surface was observed.
Conclusions:
- Light illumination, particularly short wavelengths, effectively relaxes strain in perovskite films.
- Strain relaxation leads to reduced charge trap concentration, enhancing PSC efficiency and stability.
- This study offers critical insights into light-modulated strain in PSCs.
