Dopant engineering involving molecular/ionic additives is a kind of usual technique to achieve state-of-the-art perovskite solar cells (PSCs) with favorable stability. It is critical to maximize the functions of doping agents for perovskite due to its unstable structure, inherent defect, weak water resistance, and so on. To ameliorate these problems, herein, we introduce a multi-functional halogen-free cesium trifluoroacetate (CsCF₃COO, CsTFA) into organic amine salt precursor via a conventional two-step sequential deposition approach. The carboxyl group (-COO^-) of CsTFA can passivate inherent traps that exist in perovskite crystal lattice through interacting with the Pb–I framework, which effectively suppresses non-radiative recombination and further reduces open-circuit voltage deficit. Cesium ion (Cs⁺) supplies an A-site cation to tune tolerance factor while the trifluoromethyl section (-CF₃) improves hydrophobicity of devices. These three synergistic effects finally drive the power conversion efficiency of the champion device from 21.1% to 22.3% with improved stability. This work paves a new way to enhance the performance and the stability of photovoltaic device using halogen-free doping materials.

涉及分子/离子添加剂的掺杂剂工程是一种常用技术，可实现具有良好稳定性的最先进的钙钛矿太阳能电池（PSC）。由于钙钛矿结构不稳定、固有缺陷、耐水性弱等特点，最大限度地发挥钙钛矿掺杂剂的功能至关重要。为了改善这些问题，在本文中，我们通过传统的两步顺序沉积方法将多功能无卤三氟乙酸铯（CsCF ₃ COO，CsTFA）引入有机胺盐前体中。羧基（-COO ^-)的CsTFA可以通过与Pb-I骨架相互作用钝化钙钛矿晶格中存在的固有陷阱，有效抑制非辐射复合并进一步降低开路电压不足。铯离子 (Cs ⁺ ) 提供 A 位阳离子以调节耐受因子，而三氟甲基部分 (-CF ₃ ) 可提高器件的疏水性。这三种协同效应最终将冠军设备的功率转换效率从 21.1% 提高到 22.3%，并提高了稳定性。这项工作为使用无卤掺杂材料提高光伏器件的性能和稳定性开辟了一条新途径。