He Xu, Li Chunxiu, Wu Lili, Hao Xia, Zhang Jingquan, Feng Lianghuan, Tang Peng, Du Zheng
Chengdu Textile College Chengdu 611731 China
College of Materials Science and Engineering, Sichuan University Chengdu 610065 China
RSC Adv. 2022 Aug 10;12(34):22188-22196. doi: 10.1039/d2ra03053e. eCollection 2022 Aug 4.
The short-circuit current density ( ) of CdTe solar cells both in the short and long wavelength regions can be effectively enhanced by using CdS/CdSe as the composite window layer. CdS/CdSe composite layers would interdiffuse to form the CdSe S ternary layer during the high temperature deposition process of CdTe films. In this paper, the electronic properties of CdSe S (0 ≤ ≤ 1) ternary alloys are investigated by first-principles calculation based on the density functional theory (DFT) and the performance of CdS/CdSe/CdTe devices are modeled by SCAPS to reveal why CdS/CdSe complex layers have good effects. The calculation results show that the position of the valence band of CdSe S moves towards the vacuum level as the doping concentration of Se increases and the band gap becomes narrow. According to device modeling, the highest conversion efficiency of 20.34% could be achieved through adjusting the conduction band offset (CBO) of theCdSe S /CdTe interface to about 0.11 eV while the Se concentration approaches 0.75. Further investigations suggest a 50-120 nm thickness of CdSe S ( = 0.75) would obtain better device performance. It means that solar cells with a CdSe S /CdTe structure need a suitable Se content and thickness of CdSe S . These results can provide theoretical guidance for the design and fabrication of high efficiency CdTe solar cells.
通过使用硫化镉/硒化镉作为复合窗口层，可以有效提高碲化镉太阳能电池在短波和长波区域的短路电流密度（ ）。在碲化镉薄膜的高温沉积过程中，硫化镉/硒化镉复合层会相互扩散形成CdSe S三元层。本文基于密度泛函理论（DFT）通过第一性原理计算研究了CdSe S（0≤ ≤1）三元合金的电子性质，并通过SCAPS对硫化镉/硒化镉/碲化镉器件的性能进行建模，以揭示为什么硫化镉/硒化镉复合层具有良好的效果。计算结果表明，随着硒掺杂浓度的增加，CdSe S价带位置向真空能级移动，带隙变窄。根据器件建模，当硒浓度 接近0.75时，通过将CdSe S/CdTe界面的导带偏移（CBO）调整到约0.11 eV，可实现最高20.34%的转换效率。进一步研究表明，50 - 120 nm厚度的CdSe S（ = 0.75）将获得更好的器件性能。这意味着具有CdSe S/CdTe结构的太阳能电池需要合适的硒含量和CdSe S厚度。这些结果可为高效碲化镉太阳能电池的设计和制造提供理论指导。
