Light relaxes hybrid perovskites Ion migration in organic-inorganic perovskite solar cells limits device stability and performance. Tsai et al. found that a cesium-doped lead triiodide perovskite with mixed organic cations underwent a uniform lattice expansion after 180 min of exposure at 1 sun of illumination. This structural change reduced the energy barriers for charge carriers at the contacts of solar cells. The resulting increase in power conversion efficiency from 18.5 to 20.5% was maintained for more than 1500 hours of illumination. Science, this issue p. 67 Light-induced lattice expansion improves crystallinity and relaxes lattice strain in organic-inorganic perovskite films. Light-induced structural dynamics plays a vital role in the physical properties, device performance, and stability of hybrid perovskite–based optoelectronic devices. We report that continuous light illumination leads to a uniform lattice expansion in hybrid perovskite thin films, which is critical for obtaining high-efficiency photovoltaic devices. Correlated, in situ structural and device characterizations reveal that light-induced lattice expansion benefits the performances of a mixed-cation pure-halide planar device, boosting the power conversion efficiency from 18.5 to 20.5%. The lattice expansion leads to the relaxation of local lattice strain, which lowers the energetic barriers at the perovskite-contact interfaces, thus improving the open circuit voltage and fill factor. The light-induced lattice expansion did not compromise the stability of these high-efficiency photovoltaic devices under continuous operation at full-spectrum 1-sun (100 milliwatts per square centimeter) illumination for more than 1500 hours.

中文翻译：

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光致晶格膨胀导致高效钙钛矿太阳能电池

光松弛混合钙钛矿 有机-无机钙钛矿太阳能电池中的离子迁移限制了器件的稳定性和性能。蔡等人。发现具有混合有机阳离子的掺铯三碘化铅钙钛矿在 1 太阳光照射 180 分钟后经历了均匀的晶格膨胀。这种结构变化降低了太阳能电池触点处电荷载流子的能量障碍。由此产生的功率转换效率从 18.5% 提高到 20.5%，可维持 1500 多个小时的照明。科学，这个问题 p。67 光致晶格膨胀提高了结晶度并松弛了有机-无机钙钛矿薄膜中的晶格应变。光致结构动力学在基于混合钙钛矿的光电器件的物理特性、器件性能和稳定性中起着至关重要的作用。我们报告说，连续光照导致混合钙钛矿薄膜中的均匀晶格膨胀，这对于获得高效光伏器件至关重要。相关的原位结构和器件表征表明，光致晶格膨胀有利于混合阳离子纯卤化物平面器件的性能，将功率转换效率从 18.5% 提高到 20.5%。晶格膨胀导致局部晶格应变松弛，从而降低钙钛矿-接触界面的能量势垒，从而提高开路电压和填充因子。