碲化镉薄膜太阳电池中的关键科学问题研究

文章对CdTe薄膜太阳电池中的4个关键科学问题进行了讨论，并对电池器件的性能进行了研究，其中包括高质量硫化镉薄膜、背接触层、CdS/CdTe界面和CdCl2热处理性能的研究。文章作者研究了背电极接触层中Cu掺杂含量对电池性能的影响，通过改变背接触层中Cu的含量，可以改变Cu与Te反应产生的物相成分，从而发现以Cu1.4Te为主导的背接触缓冲层能有效地减少电池I—V 曲线中的“翻转”(roll-over)现象，同时能有效地降低背接触势垒。此外，还研究了CdS/CdTe界面的CdCl2热处理反应，发现当热处理温度高于350℃时，CdS与CdTe之间的互扩散开始发生，此温度对应于CdS由立方相转变为六方相；而在550℃热处理后，S 和Te 互扩散形成的CdSxTe1-x 化合物，其x 值高达11%。通过优化电池制备工艺，获得了在AM1.5标准光源下高达14.6%的CdTe电池转换效率。

Critical issues of CdTe thin film solar cells

Four critical issues related to high efficiency CdTe thin film solar cell are discussed and studied: the quality of CdS films, back contact, CdS/CdTe interface formation, and CdCl2 heat treatment. Through control of the copper doping in the back contact we have eliminated the roll-over phenomenon in the I-V curve. The back contact barrier was reduced by formation of a Cu1.4Te compound which has a good contact with CdTe. Systematic investigations showed that relatively strong interdiffusion at the CdS/CdTe interface began to occur at around 350°C. This temperature coincides with the CdS phase transformation from cubic to hexagonal. Both S- and Te-rich CdSxTe1-x alloy formed at the interface, with x as much as 11%. Through optimization of the cell fabrication process, a CdTe solar cell efficiency as high as 14.6% has been obtained.