CdTe太阳电池的不同背电极和背接触层的特性研究

Performance of CdTe solar cells with different back electrodes and back contact layers

用Ni替代Au来作为CdTe太阳电池的背电极,比较了Ni,Ni/Au,Au/Ni及Au背电极对电池性能的影响.发现Ni作为背电极和ZnTe/ZnTe:Cu复合层接触,电池的开路电压Voc略有降低,填充因子FF有增有减,变化幅度不大,但因短路电流Isc有较大的提高,转换效率η平均增长4%.测试了不同背电极的CdTe太阳电池的暗I-V和C-V特性,对背电极剥离后的样品进行了XPS测试分析.结果表明,Ni扩散到ZnTe/ZnTe:Cu复合层的深度比Au多,且大多呈离子态,与ZnTe/ZnTe:Cu复合层中的富Te离子形成NixTe,提高了掺杂浓度,使电池性能获得改善.

In this paper, the effects of Ni and Au back electrode on the performance of CdTe solar cells and the mechanisms have been studied by experiment. Among the back electrodes of Ni, Ni/Au, Au/Ni and Au film, only when the Ni film contacts the ZnTe/ ZnTe：Cu complex layers, does the conversion efficiency increase with the short current increasing. So it is probable that the conversion efficiencies of cells will be increased by 4% at least, and the cost in large scale manufacturing will be cut down. By analyzing the dark C- VI I- V cures and the XPS using different back electrode films, it has been found the concentration and depth of Ni diffusion in the ZnTe/ZnTe：Cu back contact layer are greater than that of Au. What＇s more, most Ni^x＋ combine with the abundant Te ions in ZnTe/ZnTe： Cu back contact layer to form the Ni, Te. So the diffusion concentration is increased, which makes the characters of CdTe improved.