【摘要】 二维CsPbI₃钙钛矿太阳能电池由于出色的稳定性受到了广泛关注.然而,二维结构中有机阳离子与无机平面之间复杂的相互作用限制了其光电转换效率的进一步提高.为此,作者从功能化有机阳离子的角度出发,将含氟间隔阳离子应用于构筑二维D-J CsPbI₃器件.首先借助第一性原理计算分析了二维钙钛矿结构中功能化有机阳离子与无机平面的耦合情况,揭示了含氟有机阳离子能够增加二维结构中的介电常数,减小激子结合能,并优化能量传输路径.进一步从实验上证明了含氟有机阳离子对增加二维钙钛矿薄膜的结晶度、降低缺陷态密度,优化载流子的提取与传输等过程具有积极意义.基于此,本文实现了二维D-J CsPbI₃器件的记录效率以及良好的运行稳定性.本工作从优化二维D-J CsPbI₃结构中能量传输路径的角度出发,思考了器件性能与材料微观结构之间的关系,为二维CsPbI₃器件性能的进一步发展提供了新的思路.更多还原

【Abstract】 Two-dimensional（2D） Dion-Jacobson（D-J）-type cesium lead iodide CsPbI₃ perform remarkably in terms of stability. However, the complex interactions between spacer and inorganic layers limit its excellent progress in perovskite solar cells（PSCs）. Herein, starting from the considerable structural diversity of organic spacers, we engineer 2D CsPbI₃ with fine-tuning functionalities. Specifically, for the first time we embedded fluorinated aromatic cations in 2D D-J CsPbI₃, and successfully applied it into construction of high-performance PSCs. Compared with constitutive 1,4-diaminobenzene（PDA）, the fluorinated 2-fluorobenzene-1,4-diamine（F-PDA） component greatly expands the dipole moment from 0.59 D to 3.47 D, which reduces the exciton binding energy of the system. A theoretical study shows that the spacer layer and inorganic plane are more enriched with charge accumulation in（F-PDA）Csn±1 Pb_nI_3n+1. The results show that（F-PDA）Csn±1Pb_nI_3n+1 demonstrates more significant charge transfer between organic and inorganic layers than（PDA）Csn±1 Pb_nI_3n+1, and it is confirmed in the femtosecond transient absorption experiment. Moreover, the interactions of the fluorinated spacer with the [PbI₆]^4- plane effectively manipulate the crystallization quality, and thus the ion migration and defect formation of target 2D CsPbI₃ are inhibited. As a result, we obtained a record power conversion efficiency（PCE） beyond 15%for 2D D-J（F-PDA）Cs₃Pb₄I₁₃（n = 4） PSCs with significantly improved environmental stability compared with the three-dimensional（3D） counterparts.更多还原