Surface passivation of metal halide perovskite thin films has proved to be critical for efficient and stable perovskite solar cells (PSCs), i.e. suppressing charge recombination at the interfaces between perovskite and charge transport layers for high device efficiency and preventing the penetration of degrading agents into the perovskite layer for high device stability. Here, we report the use of a new class of materials, phosphonium halide salts, i.e. triphenyl(9-ethyl-9H-carbazol-3-yl)-phosphonium bromide (TCPBr) and iodide (TCPI), as surface passivation agents for efficient and stable PSCs. Suppressed nonradiative recombination and enhanced interfacial hole extraction, enabled by this facile phosphonium halide passivation, resulted in PSCs with power conversion efficiencies (PCEs) of >20.1% (∼18.5% for pristine MAPbI₃ devices). Phosphonium halide passivation also reduced the hysteresis index from 11.2% (pristine device) to 5.4% (TCPBr passivated device). Moreover, the hydrophobic phosphonium halide passivation layers significantly suppressed moisture penetration and ion migration, greatly enhancing the device stability. It was found that unencapsulated solar cells based on TCPBr treated MAPbI₃ thin layers retained more than 90% of the initial PCEs after more than 1000 hours storage under ambient conditions. Our work established the potential of phosphonium-based materials for surface passivation of metal halide perovskites, providing a new route towards efficient and stable perovskite optoelectronic devices.

中文翻译：

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卤化ovski对钙钛矿薄膜的表面钝化，可实现高效稳定的太阳能电池†

事实证明，金属卤化物钙钛矿薄膜的表面钝化对于有效和稳定的钙钛矿太阳能电池（PSC）至关重要，即抑制钙钛矿和电荷传输层之间界面处的电荷复合以提高器件效率，并防止降解剂渗透到钙钛矿中。钙钛矿层，具有较高的设备稳定性。在这里，我们报告了新型材料卤化phospho盐的使用，即三苯基（9-乙基-9 H-咔唑-3-基）-溴化phosph（TCPBr）和碘化物（TCPI），作为有效，稳定的PSC的表面钝化剂。通过这种简便的卤化nium钝化作用，抑制了非辐射重组并增强了界面空穴的提取，导致了功率转换效率（PCE）> 20.1％的PSC（原始MAPbI ₃器件的功率转换效率为18.5％）。卤化磷钝化还将磁滞指数从11.2％（原始设备）降低到5.4％（TCPBr钝化设备）。此外，疏水性卤化phospho钝化层显着抑制了水分渗透和离子迁移，从而大大提高了器件的稳定性。发现基于TCPBr处理的MAPbI _3的未封装太阳能电池在环境条件下存储超过1000小时后，薄层保留了90％的初始PCE。我们的工作建立了phospho基材料在金属卤化物钙钛矿表面钝化方面的潜力，为高效，稳定的钙钛矿光电器件提供了一条新途径。