The Effect of the CdCl2 Heat Treatment on CdSexTe1-x Solar Cells

In this paper we report results on Cdxex'Iei.x based solar cells, fabricated by inter-diffusing CdTe/CdSe bilayers. The effect of the CdCh heat treatment (HT) carried out at various temperatures on bilayers with different CdSe thicknesses has been investigated. The CdCh HT temperature has been found to be critical for intermixing; to-date it has been shown that higher temperature leads to enhanced inter-diffusion, which also leads to higher short circuit current (Jsc) due to a decrease in the band gap of the absorber. Large CdSe thicknesses $(> 300_{\lrcorner}L)$ lead to lower open circuit voltage (Voc) and fill factor (FF). Optimization of the annealing temperature and CdSe thickness has yielded cells with Voc $=850\mathrm{mV}, Jsc =26.3\mathrm{mA}/\mathrm{cm}^{2}, \mathrm{FF}=73$ % and efficiency 16.3%.