Understanding the role of selenium in defect passivation for highly efficient selenium-alloyed cadmium telluride solar cells
Understanding the role of selenium in defect passivation for highly efficient selenium-alloyed cadmium telluride solar cells
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DOI：
10.1038/s41560-019-0389-z
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发表时间：
2019-06-01
期刊：
影响因子：
56.7
通讯作者：
Walls, John M.
中科院分区：
文献类型：
--
作者：
Fiducia, Thomas A. M.;Mendis, Budhika G.;Walls, John M.
碲化镉(CdTe)光伏组件生产的电力是太阳能行业中成本最低的电力，目前在世界许多地区都低于化石燃料能源。这是由于最近在镉镉吸收体中加入硒带来的效率提高，使电池效率从19.5%提高到目前创纪录的22.1%。虽然众所周知，添加硒可以减小吸波材料的带隙，从而增加电池的短路电流，但这种效应本身并不能解释性能的改善。在这里，通过阴极发光和二次离子质谱仪，我们证明了硒能够使合金材料中更高的发光效率和更长的扩散长度，这表明硒钝化了吸收层大部分的关键缺陷。这种钝化效应解释了硒合金CdTe器件创纪录的性能，并为进一步提高效率提供了途径，从而可以降低太阳能发电的成本。
Electricity produced by cadmium telluride (CdTe) photovoltaic modules is the lowest-cost electricity in the solar industry, and now undercuts fossil fuel-based sources in many regions of the world. This is due to recent efficiency gains brought about by alloying selenium into the CdTe absorber, which has taken cell efficiency from 19.5% to its current record of 22.1%. Although the addition of selenium is known to reduce the bandgap of the absorber material, and hence increase the cell short-circuit current, this effect alone does not explain the performance improvement. Here, by means of cathodoluminescence and secondary ion mass spectrometry, we show that selenium enables higher luminescence efficiency and longer diffusion lengths in the alloyed material, indicating that selenium passivates critical defects in the bulk of the absorber layer. This passivation effect explains the record-breaking performance of selenium-alloyed CdTe devices, and provides a route for further efficiency improvement that can result in even lower costs for solar-generated electricity.