Hu Zhelu, An Qingzhi, Xiang Hengyang, Aigouy Lionel, Sun Baoquan, Vaynzof Yana, Chen Zhuoying
Laboratoire de Physique et d'Étude des matériaux (LPEM, UMR 8213), ESPCI Paris, PSL University, CNRS, Sorbonne University, 10 Rue Vauquelin, 75005 Paris, France.
Integrated Centre for Applied Physics and Photonic Materials and Centre for Advancing Electronics Dresden (cfaed), Technical University of Dresden, Nöthnitzer Str. 61, 01187 Dresden, Germany.
ACS Appl Mater Interfaces. 2020 Dec 9;12(49):54824-54832. doi: 10.1021/acsami.0c17258. Epub 2020 Nov 23.
Metal halide perovskites are promising contenders for next-generation photovoltaic applications due to their remarkable photovoltaic efficiency and their compatibility with solution-processed fabrication. Among the various strategies to control the crystallinity and the morphology of the perovskite active layer and its interfaces with the transport layers, fabrication of perovskite solar cells from precursor solutions with a slight excess of PbI has become very common. Despite this, the role of such excess PbI is still rather controversial, lacking consensus on its effect on the bulk and interface properties of the perovskite layer. In this work, we investigate the effect of removing the excess PbI from the surface of a triple-cation mixed-halide Cs(FAMA)Pb(IBr) perovskite layer by four different organic salts on their photovoltaic performance and stability. We show that treatments with iodide salts such as methylammonium iodide (MAI) and formamidinium iodide (FAI) can lead to the strongest beneficial effects on solar cell efficiency, charge recombination suppression, and stability while non-iodide salts such as methylammonium bromide (MABr) and methylammonium chloride (MACl) can also provide improvement in terms of charge recombination suppression and stability to a moderate extent in comparison to the untreated sample. Under optimized conditions and continuous solar illumination, the MAI- and FAI-treated devices maintained 81 and 86% of their initial power conversion efficiency (PCEs), respectively, after 100 h of continuous illumination (versus 64% for the untreated solar cell with excess PbI). Our study demonstrates that eliminating excess PbI at the perovskite/hole transport layer (HTL) interface by treating the perovskite surface with organic salts is a simple and efficient route to enhance the efficiency, and in particular the stability of perovskite solar cells.
金属卤化物钙钛矿因其卓越的光伏效率以及与溶液处理制造工艺的兼容性，成为下一代光伏应用的有力竞争者。在控制钙钛矿活性层及其与传输层界面的结晶度和形貌的各种策略中，使用略微过量的PbI的前驱体溶液制备钙钛矿太阳能电池已变得非常普遍。尽管如此，这种过量PbI的作用仍颇具争议，对于其对钙钛矿层的体相和界面性质的影响尚未达成共识。在这项工作中，我们研究了用四种不同的有机盐从三阳离子混合卤化物Cs(FAMA)Pb(IBr)钙钛矿层表面去除过量PbI对其光伏性能和稳定性的影响。我们表明，用碘化盐如甲基碘化铵(MAI)和甲脒碘化铵(FAI)处理可对太阳能电池效率、电荷复合抑制和稳定性产生最强的有益影响，而与未处理样品相比，非碘化盐如甲基溴化铵(MABr)和甲基氯化铵(MACl)在电荷复合抑制和稳定性方面也能提供一定程度的改善。在优化条件和持续太阳光照下，经MAI和FAI处理的器件在持续光照100小时后分别保持其初始功率转换效率(PCEs)的81%和86%（未处理的含过量PbI的太阳能电池为64%）。我们的研究表明，通过用有机盐处理钙钛矿表面来消除钙钛矿/空穴传输层(HTL)界面处的过量PbI是提高效率，特别是提高钙钛矿太阳能电池稳定性的一种简单有效的途径。
