Facet-dependent photovoltaic efficiency variations in single grains of hybrid halide perovskite
Facet-dependent photovoltaic efficiency variations in single grains of hybrid halide perovskite
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DOI：
10.1038/nenergy.2016.93
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发表时间：
2016-07-04
期刊：
影响因子：
56.7
通讯作者：
Weber-Bargioni, Alexander
中科院分区：
文献类型：
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作者：
Leblebici, Sibel Y.;Leppert, Linn;Weber-Bargioni, Alexander
由于载流子迁移率高、寿命长，基于混合钙钛矿材料的光伏器件效率已超过 22%。光电流产生和开路电压等特性受到钙钛矿晶体的微观结构和取向的影响，但很难在晶粒内长度尺度上量化，并且通常被视为有源层内的均匀性。在这里，我们使用光电导原子力显微镜绘制了最先进的甲基铵碘化铅太阳能电池中的局部短路光电流、开路光电压和暗漂移电流。我们发现，在单个晶粒内，短路电流和开路电压的空间相关异质性高达 0.6V。这些变化与不同晶面有关，对宏观功率转换效率有直接影响。我们将这种异质性归因于与面相关的陷阱态密度。这些结果意味着控制晶粒和晶面取向将能够系统地优化用于光伏和照明应用的多晶和单晶器件。
Photovoltaic devices based on hybrid perovskite materials have exceeded 22% efficiency due to high charge-carrier mobilities and lifetimes. Properties such as photocurrent generation and open-circuit voltage are influenced by the microscopic structure and orientation of the perovskite crystals, but are difficult to quantify on the intra-grain length scale and are often treated as homogeneous within the active layer. Here, we map the local short-circuit photocurrent, open-circuit photovoltage, and dark drift current in state-of-the-art methylammonium lead iodide solar cells using photoconductive atomic force microscopy. We find, within individual grains, spatially correlated heterogeneity in short-circuit current and open-circuit voltage up to 0.6V. These variations are related to different crystal facets and have a direct impact on the macroscopic power conversion efficiency. We attribute this heterogeneity to a facet-dependent density of trap states. These results imply that controlling crystal grain and facet orientation will enable a systematic optimization of polycrystalline and single-crystal devices for photovoltaic and lighting applications.