材料科学
带隙
锡
钙钛矿(结构)
光致发光
甲脒
鞠躬
三碘化物
光电子学
载流子
兴奋剂
化学物理
结晶学
化学
电解质
物理化学
冶金
哲学
色素敏化染料
神学
电极
作者
Elizabeth S. Parrott,Thomas Green,Rebecca L. Milot,Michael B. Johnston,Henry J. Snaith,Laura M. Herz
标识
DOI:10.1002/adfm.201802803
摘要
Abstract Mixed lead–tin triiodide perovskites are promising absorber materials for low bandgap bottom cells in all‐perovskite tandem photovoltaic devices. Key structural and electronic properties of the FAPb 1− x Sn x I 3 perovskite are presented here as a function of lead:tin content across the alloy series. Temperature‐dependent photoluminescence and optical absorption measurements are used to identify changes in the bandgap and phase transition temperature. The large bandgap bowing parameter, a crucial element for the attainment of low bandgaps in this system, is shown to depend on the structural phase, reaching a value of 0.84 eV in the low‐temperature phase and 0.73 eV at room temperature. The parabolic nature of the bowing at all temperatures is compatible with a mechanism arising from bond bending to accommodate the random placement of unevenly sized lead and tin ions. Charge‐carrier recombination dynamics are shown to fall into two regimes. Tin‐rich compositions exhibit fast, monoexponential recombination that is almost temperature‐independent, in accordance with high levels of electrical doping. Lead‐rich compositions show slower, stretched‐exponential charge‐carrier recombination that is strongly temperature‐dependent, in accordance with a multiphonon assisted process. These results highlight the importance of structure and composition for control of bandgap bowing and charge‐carrier recombination mechanisms in low bandgap absorbers for all‐perovskite tandem solar cells.
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