Preparation of CuSe nanoparticles by antisolvent process for doping and passivation of absorber layer in CdTe solar cells

The p-type doping and passivation of the back surface of the CdTe absorber layer are two key steps to enhance the performance of CdTe thin film solar cells. In recent years, different Cu-doped precursors (Cu (I) and Cu (II) materials) and passivation materials (elements such as Se, Cl, Al, etc.) have been investigated. However, few researchers have proposed in new materials on both doping and passivation functions for backside applications. Here, CuSe, which combines the potential of p-type doping and Se passivation functions, is proposed for the first time as a doping precursor for the CdTe absorber layer. A certain amount of CuSe nanoparticles was deposited on the back surface of the CdTe absorber layer based on an antisolvent deposition process. The results show that the optimal device open-circuit voltage of the CuSe-treated CdTe solar cell reaches 842.5 mV, which is similar to 6.5 % higher than that of the CuCl2-treated CdTe device (791.4 mV). The results of current-voltage and Mott-Schottky, impedance spectrum show that the CuSe-treated CdTe device not only achieves the purpose of p-type doping, but also introduces the passivation function of Se.