Overcoming Redox Reactions at Perovskite-Nickel Oxide Interfaces to Boost Voltages in Perovskite Solar Cells
Overcoming Redox Reactions at Perovskite-Nickel Oxide Interfaces to Boost Voltages in Perovskite Solar Cells
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DOI：
10.1016/j.joule.2020.06.004
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发表时间：
2020-08-19
期刊：
影响因子：
39.8
通讯作者：
McGehee, Michael D.
中科院分区：
文献类型：
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作者：
Boyd, Caleb C.;Shallcross, R. Clayton;McGehee, Michael D.
氧化镍（NiOx）空穴传输层（HTL）是钙钛矿光致发光材料的理想接触，因为它们成本低、稳定且易于扩展;然而，与有机HTL相比，它们提供较低的开路电压（V（OC）s）。在这里，我们表征和减轻NiOx HTLs和钙钛矿前体之间的电子转移-质子转移反应。利用XPS和UPS表征，我们确定NiOx薄膜中Ni ≥ 3+金属阳离子位点既充当Bronsted质子受体又充当刘易斯电子受体，使阳离子胺去质子化并氧化碘物种，在钙钛矿-NiOx处形成富含PbI 2-xBrx的空穴提取势垒。接口.在钙钛矿活性层沉积期间用过量的A位阳离子盐滴定反应性Ni >= 3+表面状态产生V-OC值增加至1.15V和类似于20%的功率转换效率。这可能是对金属氧化物接触的一般发现，所述金属氧化物接触充当朝向钙钛矿前体的布朗斯台德和刘易斯酸碱反应物，最近还对TiO 2和SnO 2接触进行了观察。
Nickel oxide (NiOx) hole transport layers (HTLs) are desirable contacts for perovskite photovoltaics because they are low cost, stable, and readily scalable; however, they deliver lower open-circuit voltages (V(OC)s) compared to organic HTLs. Here, we characterize and mitigate electron transfer-proton transfer reactions between NiOx HTLs and perovskite precursors. Using XPS and UPS characterization, we identify that Ni >= 3+ metal cation sites in NiOx thin films act both as Bronsted proton acceptors and Lewis electron acceptors, deprotonating cationic amines and oxidizing iodide species, forming PbI2-xBrx-rich hole extraction barriers at the perovskite-NiOx. interface. Titrating reactive Ni >= 3+ surface states with excess A-site cation salts during perovskite active layer deposition yielded an increase in V-OC values to 1.15 V and power conversion efficiencies of similar to 20%. This may be a general finding for metal oxide contacts that act as Bronsted and Lewis acid-base reactants toward perovskite precursors, an observation that has also been made recently for TiO2 and SnO2 contacts.