NH $_{f 4}$ Cl Alternative to the CdCl $_{f 2}$ Treatment Step for CdTe Thin-Film Solar Cells

The CdCl 2 treatment is a key step in CdTe solar cell fabrication. However, despite its near ubiquitous use, the process is nonideal as CdCl 2 is both expensive and potentially hazardous to utilize in processing. In this paper, we report on the development of a NH 4 Cl replacement to the CdCl 2 process, which is a low-cost noncarcinogenic alternative. Comparative cells were fabricated and compared via C -V, J-V, scanning electron microscopy, and external quantum efficiency analysis. Further process optimization led to device efficiencies of up to 11.5%, achieved using this new process, with V OC values of up to 832 mV, which is relatively high.