PbI_(2)对钙钛矿薄膜及太阳电池性能的影响

Effects of PbI_(2) on the Performances of Perovskite Thin Films and Solar Cells

碘化铅(PbI_(2))是两步法制备钙钛矿薄膜最常使用的金属卤化物前驱体,精确控制PbI_(2)在钙钛矿薄膜中的含量和空间分布以及优化PbI_(2)薄膜的形貌结构对于制备高效稳定的太阳电池具有重要意义。探索了PbI_(2)的浓度和退火方式对钙钛矿薄膜及太阳电池性能的影响。研究发现,PbI_(2)溶液的浓度不仅决定钙钛矿薄膜中PbI_(2)的含量,也影响钙钛矿的晶粒尺寸、取向及光学吸收等性质,从而导致器件性能的改变,当钙钛矿薄膜表面分布约45%的PbI_(2)时器件性能更佳。此外,PbI_(2)的形貌、结晶性和孔隙度受退火方式的影响显著,与溶剂退火相比,通过短暂的1 min热退火制备的PbI_(2)薄膜更有利于减少钙钛矿表界面缺陷,提升器件的开路电压,最终使器件的基础光电转换效率(PCE)可以提升至20.89%。上述研究结果有助于进一步优化钙钛矿太阳电池制备工艺,提升器件性能。

Lead iodide(PbI_(2)) is the most commonly used metal halide precursor for the preparation of perovskite thin films by two-step method. It is of great significance to precisely control the contents and spatial distribution of PbI_(2)in perovskite thin films and optimize the morphology and structure of PbI_(2)thin films for the preparation of efficient and stable solar cells. The effects of PbI_(2)concentration and annealing method on the properties of perovskite thin films and the performance of solar cells were investigated. It is found that the concentration of PbI_(2)solution determines the concents of PbI_(2)in perovskite thin films, and affects its grain size, orientation and optical absorption, resulting in the changes in the performance of devices. When the distribution of PbI_(2)on the surface of perovskite thin film is about 45%, the device performance is better. Furthermore, the morphology, crystallinity and porosity of PbI_(2)are also significantly affected by the annealing method. Compared with the solvent annealing, the PbI_(2)thin film prepared by short thermal annealing for 1 min is more conducive to decrease of the surface and interface defects of the perovskite thin films and improve the open-circuit voltage of the device. Finally, the basic photoelectric conversion efficiency(PCE) of the device can increase up to 20.89%. The above research results are helpful to further optimize the fabrication process of perovskite solar cells and improve the device performances.