Solid State and Structural Chemistry Unit, Indian Institute of Science , Bangalore 560012, India.
ACS Nano. 2013 Dec 23;7(12):11055-63. doi: 10.1021/nn404749n. Epub 2013 Nov 21.
Semiconductor nanocrystals of different formulations have been extensively studied for use in thin-film photovoltaics. Materials used in such devices need to satisfy the stringent requirement of having large absorption cross sections. Hence, type-II semiconductor nanocrystals that are generally considered to be poor light absorbers have largely been ignored. In this article, we show that type-II semiconductor nanocrystals can be tailored to match the light-absorption abilities of other types of nanostructures as well as bulk semiconductors. We synthesize type-II ZnTe/CdS core/shell nanocrystals. This material is found to exhibit a tunable band gap as well as absorption cross sections that are comparable to CdTe. This result has significant implications for thin-film photovoltaics, where the use of type-II nanocrystals instead of pure semiconductors can improve charge separation while also providing a much needed handle to regulate device composition.
不同配方的半导体纳米晶体已被广泛研究用于薄膜光伏。此类器件中使用的材料需要满足具有大吸收截面的严格要求。因此，通常被认为是不良光吸收体的 II 型半导体纳米晶体在很大程度上被忽略了。在本文中，我们表明可以对 II 型半导体纳米晶体进行调整以匹配其他类型的纳米结构和体半导体的光吸收能力。我们合成了 II 型 ZnTe/CdS 核/壳纳米晶体。结果发现，这种材料表现出可调带隙以及与 CdTe 相当的吸收截面。这一结果对薄膜光伏具有重要意义，在薄膜光伏中，使用 II 型纳米晶体而不是纯半导体可以提高电荷分离效率，同时还提供了一种急需的手段来调节器件组成。
