Cacovich Stefania, Dally Pia, Vidon Guillaume, Legrand Marie, Gbegnon Stéphanie, Rousset Jean, Puel Jean-Baptiste, Guillemoles Jean-François, Schulz Philip, Bouttemy Muriel, Etcheberry Arnaud
CNRS, Institut Photovoltaïque d'Île de France (IPVF), UMR 9006, 18 boulevard Thomas Gobert, 91120 Palaiseau, France.
Institut Photovoltaïque d'Île de France (IPVF), 18 boulevard Thomas Gobert, 91120 Palaiseau, France.
ACS Appl Mater Interfaces. 2022 Aug 3;14(30):34228-34237. doi: 10.1021/acsami.1c22286. Epub 2022 Mar 4.
The investigation of chemical and optoelectronic properties of halide perovskite layers and associated interfaces is crucial to harness the full potential of perovskite solar cells. Depth-profiling photoemission spectroscopy is a primary tool to study the chemical properties of halide perovskite layers at different scales from the surface to the bulk. The technique employs ionic argon beam thinning that provides accurate layer thicknesses. However, there is an urgent need to corroborate the reliability of data on chemical properties of halide perovskite thin films to better assess their stability. The present study addresses the question of the Ar sputtering thinning on the surface chemical composition and the optoelectronic properties of the triple-cation mixed-halide perovskite by combining X-ray photoemission spectroscopy (XPS) and photoluminescence (PL) spectroscopy. First, XPS profiling is performed by Ar beam sputtering on a half-cell: glass/FTO/c-TiO/perovskite. The resulting profiles show a very homogeneous and reproducible element distribution until near the buried interface; therefore, the layer is considered as quasihomogeneous all over its thickness, and the sputtering process is stable. Second, we evaluated a set of thinned perovskite layers representative of selected steps along the profile by means of PL imaging optical measurements in both steady-state and transient regimes to assess possible perturbation of the optical properties from the surface to bulk. Obtained PL spectra inside the resulting craters show no peak shift nor phase segregation. Accordingly, the transient PL measurements do not reveal any changes of the surface recombination rate in the sputtered areas. This demonstrates that there is no cumulative effect of sputtering nor drastic chemical and optoelectronic modifications, validating the determination of the in-depth composition of the perovskite layer. Combining XPS profiling with PL characterization can be a precise tool to be applied for an extensive study of the multiple layers and mixed organic/inorganic interfaces of photovoltaic devices.
研究卤化物钙钛矿层及其相关界面的化学和光电性质对于充分发挥钙钛矿太阳能电池的潜力至关重要。深度剖析光发射光谱是研究卤化物钙钛矿层从表面到体相不同尺度化学性质的主要工具。该技术采用离子氩束减薄，可提供精确的层厚度。然而，迫切需要证实卤化物钙钛矿薄膜化学性质数据的可靠性，以便更好地评估其稳定性。本研究通过结合X射线光电子能谱（XPS）和光致发光（PL）光谱，解决了氩溅射减薄对三阳离子混合卤化物钙钛矿表面化学成分和光电性质的影响问题。首先，通过氩束溅射在半电池上进行XPS剖析：玻璃/FTO/c-TiO/钙钛矿。所得剖析结果显示，直到接近掩埋界面，元素分布都非常均匀且可重复；因此，该层在其整个厚度范围内被视为准均匀的，并且溅射过程是稳定的。其次，我们通过稳态和瞬态条件下的PL成像光学测量，评估了一组沿剖析曲线选定步骤代表的减薄钙钛矿层，以评估从表面到体相光学性质可能受到的扰动。在所得坑内获得的PL光谱未显示峰位移或相分离。相应地，瞬态PL测量未揭示溅射区域表面复合率的任何变化。这表明不存在溅射累积效应以及剧烈的化学和光电改性，验证了钙钛矿层深度成分的测定。将XPS剖析与PL表征相结合可以成为一种精确工具，用于广泛研究光伏器件的多层和有机/无机混合界面。
