| Autor: |
Zhao, Yicheng, Miao, Peng, Elia, Jack, Hu, Huiying, Wang, Xiaoxia, Heumueller, Thomas, Hou, Yi, Matt, Gebhard J., Osvet, Andres, Chen, Yu-Ting, Tarragó, Mariona, de Ligny, Dominique, Przybilla, Thomas, Denninger, Peter, Will, Johannes, Zhang, Jiyun, Tang, Xiaofeng, Li, Ning, He, Chenglin, Pan, Anlian |
| Předmět: |
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| Zdroj: |
Nature Communications; 12/10/2020, Vol. 11 Issue 1, p1-9, 9p |
| Abstrakt: |
Light-induced halide segregation limits the bandgap tunability of mixed-halide perovskites for tandem photovoltaics. Here we report that light-induced halide segregation is strain-activated in MAPb(I1−xBrx)3 with Br concentration below approximately 50%, while it is intrinsic for Br concentration over approximately 50%. Free-standing single crystals of CH3NH3Pb(I0.65Br0.35)3 (35%Br) do not show halide segregation until uniaxial pressure is applied. Besides, 35%Br single crystals grown on lattice-mismatched substrates (e.g. single-crystal CaF2) show inhomogeneous segregation due to heterogenous strain distribution. Through scanning probe microscopy, the above findings are successfully translated to polycrystalline thin films. For 35%Br thin films, halide segregation selectively occurs at grain boundaries due to localized strain at the boundaries; yet for 65%Br films, halide segregation occurs in the whole layer. We close by demonstrating that only the strain-activated halide segregation (35%Br/45%Br thin films) could be suppressed if the strain is properly released via additives (e.g. KI) or ideal substrates (e.g. SiO2). Mixed-halide perovskites are of interest for photovoltaic devices, but light-induced halide segregation obstructs bandgap tuning and is not fully understood. Here the authors study the effects of strain and iodide/bromide ratio on light-induced halide segregation in mixed-halide perovskites. [ABSTRACT FROM AUTHOR] |
| Databáze: |
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