Zhang Jingru, Che Bo, Zhao Wangen, Fang Yuankun, Han Ruijie, Yang Yan, Liu Jiali, Yang Tengteng, Chen Tao, Yuan Ningyi, Ding Jianning, Liu Shengzhong Frank
Key Laboratory for Applied Surface and Colloid Chemistry, National Ministry of Education; Shaanxi Engineering Lab for Advanced Energy Technology, School of Materials Science and Engineering, Shaanxi Normal University, Xi'an, 710062, P. R. China.
Institute of Energy, Hefei Comprehensive National Science Center, Hefei, 230031, P. R. China.
Adv Mater. 2022 Oct;34(41):e2202735. doi: 10.1002/adma.202202735. Epub 2022 Sep 11.
Nonradiative losses caused by defects are the main obstacles to further advancing the efficiency and stability of perovskite solar cells (PSCs). There is focused research to boost the device performance by reducing the number of defects and deactivating defects; however, little attention is paid to the defect-capture capacity. Here, upon systematically examining the defect-capture capacity, highly polarized fluorinated species are designed to modulate the dielectric properties of the perovskite material to minimize its defect-capture radius. On the one hand, fluorinated polar species strengthen the defect dielectric-screening effect via enhancing the dielectric constant of the perovskite film, thus reducing the defect-capture radius. On the other, the fluorinated iodized salt replenishes the I-vacancy defects at the surface, hence lowering the defect density. Consequently, the power-conversion efficiency of an all-inorganic CsPbI PSC is increased to as high as 20.5% with an open-circuit voltage of 1.2 V and a fill factor of 82.87%, all of which are among the highest in their respective categories. Furthermore, the fluorinated species modification also produces a hydrophobic umbrella yielding significantly improved humidity tolerance, and hence long-term stability. The present strategy provides a general approach to effectually regulate the defect-capture radius, thus enhancing the optoelectronic performance.
由缺陷引起的非辐射损耗是进一步提高钙钛矿太阳能电池（PSC）效率和稳定性的主要障碍。目前的研究重点是通过减少缺陷数量和钝化缺陷来提高器件性能；然而，对缺陷捕获能力的关注较少。在此，在系统研究缺陷捕获能力后，设计了高度极化的氟化物种来调节钙钛矿材料的介电性能，以最小化其缺陷捕获半径。一方面，氟化极性物种通过提高钙钛矿薄膜的介电常数来增强缺陷介电屏蔽效应，从而减小缺陷捕获半径。另一方面，氟化碘盐补充了表面的碘空位缺陷，从而降低了缺陷密度。因此，全无机CsPbI PSC的功率转换效率提高到高达20.5%，开路电压为1.2 V，填充因子为82.87%，所有这些在各自类别中均处于最高水平。此外，氟化物种修饰还产生了一个疏水伞，显著提高了湿度耐受性，从而提高了长期稳定性。本策略提供了一种有效调节缺陷捕获半径的通用方法，从而提高光电性能。
