Non-destructive Evaluation of Compound Semiconductor Thin-Film Solar Cells by Photothermal Beam Deflection Technique

Abstract

In this paper, it is demonstrated that the photothermal beam deflection technique can be used for measuring the series resistance, optimum load resistance, and conversion efficiency of thin-film solar cells. This technique is also used for determining the carrier transport properties of an absorber and window layer of $\hbox {CuInS}_{2}/\hbox {In}_{2}\hbox {S}_{3}/\hbox {Ag}$-based solar cells during different stages of cell fabrication. Transport properties such as the carrier mobility, lifetime, and surface recombination velocity of the individual absorber and window layer are shown to influence the open-circuit voltage and short-circuit current of the final photovoltaic device. The cell parameters measured using the photothermal technique agree well with the electrical measurements. The principle of the technique is explained on the basis of the “mirage effect” and maximum power transfer theorem.