Nicoara Nicoleta, Manaligod Roby, Jackson Philip, Hariskos Dimitrios, Witte Wolfram, Sozzi Giovanna, Menozzi Roberto, Sadewasser Sascha
International Iberian Nanotechnology Laboratory (INL), Av. Mestre José Veiga s/n, 4715-330, Braga, Portugal.
Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden-Württemberg (ZSW), Meitnerstr. 1, 70563, Stuttgart, Germany.
Nat Commun. 2019 Sep 4;10(1):3980. doi: 10.1038/s41467-019-11996-y.
The properties and performance of polycrystalline materials depend critically on the properties of their grain boundaries. Polycrystalline photovoltaic materials - e.g. hybrid halide perovskites, copper indium gallium diselenide (CIGSe) and cadmium telluride - have already demonstrated high efficiencies and promise cost-effective electricity supply. For CIGSe-based solar cells, an efficiency above 23% has recently been achieved using an alkali-fluoride post-deposition treatment; however, its full impact and functional principle are not yet fully understood. Here, we show direct evidence for the passivation of grain boundaries in CIGSe treated with three different alkali-fluorides through a detailed study of the nanoscale optoelectronic properties. We determine a correlation of the surface potential change at grain boundaries with the open-circuit voltage, which is supported by numerical simulations. Our results suggest that heavier alkali elements might lead to better passivation by reducing the density of charged defects and increasing the formation of secondary phases at grain boundaries.
多晶材料的性质和性能严重依赖于其晶界的性质。多晶光伏材料，例如混合卤化物钙钛矿、铜铟镓硒（CIGSe）和碲化镉，已经展现出了高效率，并有望实现具有成本效益的电力供应。对于基于CIGSe的太阳能电池，最近通过碱金属氟化物后沉积处理实现了超过23%的效率；然而，其全部影响和作用原理尚未被完全理解。在这里，我们通过对纳米级光电性质的详细研究，展示了用三种不同碱金属氟化物处理的CIGSe中晶界钝化的直接证据。我们确定了晶界处表面电势变化与开路电压之间的相关性，这得到了数值模拟的支持。我们的结果表明，较重的碱金属元素可能通过降低带电缺陷的密度和增加晶界处第二相的形成而导致更好的钝化效果。
