Bowman A R, Leaver J F, Frohna K, Stranks S D, Tagliabue G, Major J D
Laboratory of Nanoscience for Energy Technologies (LNET), STI, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
Cavendish Laboratory, Department of Physics, University of Cambridge, J.J. Thomson Avenue, Cambridge, UK.
Nat Commun. 2024 Oct 9;15(1):8729. doi: 10.1038/s41467-024-52889-z.
Evidence from cross-sectional electron microscopy has previously shown that Se passivates defects in CdSeTe solar cells, and that this is the reason for better lifetimes and voltages in these devices. Here, we utilise spatially resolved photoluminescence measurements of CdSeTe thin films on glass to directly study the effects of Se on carrier recombination in the material, isolated from the impact of conductive interfaces and without the need to prepare cross-sections through the samples. We find further evidence to support Se passivation of grain boundaries, but also identify an increase in below-bandgap photoluminescence that indicates the presence of Se-enhanced defects in grain interiors. Our results show that whilst Se treatment, in tandem with Cl passivation, does increase radiative efficiencies in CdSeTe, it simultaneously increases the defect content within the grain interiors. This suggests that although it is beneficial overall, Se incorporation will still limit the maximum attainable optoelectronic properties of CdSeTe thin films.
来自横截面电子显微镜的证据此前表明，硒可钝化CdSeTe太阳能电池中的缺陷，这就是这些器件具有更长寿命和更高电压的原因。在此，我们利用玻璃上CdSeTe薄膜的空间分辨光致发光测量，直接研究硒对材料中载流子复合的影响，该影响与导电界面的影响隔离开来，且无需制备样品的横截面。我们发现了进一步的证据支持硒对晶界的钝化作用，但同时也发现带隙以下光致发光增加，这表明晶粒内部存在硒增强的缺陷。我们的结果表明，虽然硒处理与氯钝化相结合确实会提高CdSeTe中的辐射效率，但同时也会增加晶粒内部的缺陷含量。这表明，尽管总体上是有益的，但硒的掺入仍将限制CdSeTe薄膜可达到的最大光电性能。
