High efficiency CdTe solar cells with a through-thickness polycrystalline CdTe thin film
High efficiency CdTe solar cells with a through-thickness polycrystalline CdTe thin film
复制标题
DOI：
10.1039/c6ra07201a
复制
发表时间：
2016-05
期刊：
影响因子：
3.9
通讯作者：
K. Shen;Bai Zhi-zhong;Yi Deng;Ruilong Yang;Dezhao Wang;Qiang Li;Deliang Wang
中科院分区：
文献类型：
--
作者：
K. Shen;Bai Zhi-zhong;Yi Deng;Ruilong Yang;Dezhao Wang;Qiang Li;Deliang Wang
镉镉太阳电池的吸收层是由厚度为几μm的多晶镉镉薄膜制成的，要求镉镉薄膜可以由穿透厚度的镉镉颗粒组成。在这种情况下，光子产生的载流子可以传输到正接触和负接触，而不会遇到任何晶界，从而显著减少了晶界上发生的载流子散射/复合。提出并论证了氧的存在在薄膜生长过程中的重要作用之一是在生长前沿原位形成了氧化物(CdTeOx、TeOx和CdOx)、Te和CdTe的低熔点液体混合物。这种液体混合物的厚度为∼50 nm，有助于将物质从蒸气通过液体输送到液-固界面，在液-固界面上，Cd、Te和Cd-Te分子发生反应，在Cd-Te生长前沿外延沉积。在高结晶度的单晶CdS窗口层模板的辅助下，实现了沿法向穿透厚度晶粒的CdTe择优生长。用这种材料制成的CdTe太阳电池的外量子效率有了很大的提高，电池的效率高达14-15.2%。
The absorber layer in a CdTe solar cell is made of a polycrystalline CdTe thin film with a thickness of several μm. It is highly desirable that the CdTe film could be made of through-thickness CdTe grains. In such a case, the photon-generated carriers could be transported to the positive and negative contacts without encountering any grain boundaries in CdTe, thus significantly reducing the carrier scattering/recombination occurring at the grain boundary. We propose and demonstrate that one of the most important roles for the presence of oxygen during the CdTe film growth is to in situ form a low-melting liquid mixture of oxides (CdTeOx, TeOx and CdOx), Te, and CdTe on the growth front of the CdTe grain surface. This liquid mixture, having a thickness of ∼50 nm, assists material transport from the vapor through the liquid to the liquid–solid interface, where Cd, Te, and Cd–Te molecules reacted to epitaxially deposit on the CdTe growth front. Assisted by a highly crystalline mono-grained CdS window layer template, CdTe preferential growth with through-thickness grains along the normal direction of the film has been achieved. CdTe solar cells fabricated with such CdTe absorbers demonstrate much enhanced external quantum efficiency, and cells with efficiencies as high as 14–15.2% have been fabricated.