A NUMERICAL STUDY ON THE PROSPECTS OF HIGH EFFICIENCY ULTRA THIN ZnxCd1-xS/CdTe Solar Cell

Abstract

In this study, a new CdTe solar cell structure was proposed, where Zinc Cadmium Sulfide (ZnxCd1-xS) was used as window layer with an added advantage of variable bandgap. By varying the composition of the zinc content, the bandgap was varied between 2.42- 3.7 eV, thereby increasing the cell’s performance in the lower wavelength region, resulting in higher efficiency. The CdTe absorber layer was decreased to the extreme limit of 1 µm and at this thickness the proposed cell has shown acceptable range of efficiency. Moreover, the thickness of ZnxCd1-xS window layer was reduced to 60 nm with a suitable buffer layer either with zinc oxide (ZnO) or zinc stannate (Zn2SnO4) to prevent forward leakage current of ultra thin ZnxCd1-xS layer. The Analysis of Microelectronics and Photonics Structures (AMPS) 1-D software was used to simulate and analyze the cell’s performance (efficiency, FF, Voc, Jsc, temperature stability) with different variables. The results have shown that an efficiency of up to 19.5% is feasible of cost-effective ultra-thin ZnxCd1-xS/CdTe solar cell structure with 1 µm of CdTe, 60 nm of ZnxCd1-xS and 100 nm of ZnO or Zn2SO4 buffer layers. The cells stability with temperature and other material properties was also studied and analyzed.