Optimizing $\text{CdCl}_{2}$ Treatment on CdTe Solar Cells Using Spray Deposition Method

Control over the amount of
$\mathbf{CdCl}_{\boldsymbol{2}}$
used to process CdTe solar cells is important to achieving high-efficiency devices. Spraying allows for the deposition of a uniform film over a large area with strict management of the thickness of the film by modifying the spray parameters and/or the solution concentration. Here we report on the development of an ultrasonic spray system to deposit precisely administered amounts of
$\mathbf{CdCl}_{\boldsymbol{2}}$
uniformly over arbitrarily sized CdTe samples up to 6”x6”. We show that the deposited films are uniform and report on the optimum parameters for high-efficiency devices. Scanning electron microscopy was used to show that using the spray process reduces the amount of residual oxychlorides on the surface, likely leading to reduced recombination at the back interface.