Lee A. Silverman

Effect of the selenization process on structural and device properties of nanoparticle-derived CZTSSe thin films

Cu2ZnSn(S,Se)4 thin films and solar cells were fabricated using binary and ternary nanoparticle precursor films selenized using three different processes. Cross-sectional SEM images of the resulting CZTSSe solar cells do not show significant difference in microstructure. Detail analyses of the CZTSSe solar cells using current-voltage (J-V), external quantum efficiency (EQE), temperature-dependent J-V, and admittance spectroscopy (AS) were conducted to investigate the effect of the selenization process on the optical and electrical properties of the absorber.

Characterization of printed CZTSSe films for photovoltaic applications

Cu2ZnSn(S, Se)4 (CZTSSe) is a promising alternative absorber material for thin-film photovoltaic applications because of its earth-abundant constituents, tunable band gap, and high optical absorption coefficient. Using binary and ternary chalcogenide nanoparticles as precursors we have developed a chemical route to produce high efficiency CZTSSe photovoltaic (PV) devices via solution based methods. The printed CZTSSe films show an interesting microstructure consisting of an upper micrometer-sized polycrystalline layer (large-grain layer) and a bottom fine-grain layer. In this paper, we present our results on characterization of the layers including composition, electronic and optical properties. Based on the observed properties we develop a numerical model for the CZTSSe PV device and present the simulation results. We anticipate that the combination of detailed characterization and device model will help us better understand the limitations of our current devices and indicate potential improvement paths.