An approach towards the promotion of Kesterite solar cell efficiency: The use of nanostructures

Abstract

In this work, a theoretical study on the application of nanostructures to Cu2ZnSnS4 (CZTS) solar cells under the radiative limit is presented. In particular, the addition of Cu2ZnSn(SSe)4 (CZTSSe) quantum wells to CZTS host material to increase photon absorption with energies lower than the CZTS bandgap, while keeping the advantage of using a wider bandgap material for a host semiconductor to obtain open-circuit voltage values near the ones reported for CZTS solar cells is proposed. The impact of the well number, well thickness, and S/(S + Se) compositional ratio at barriers and wells on solar cell characteristics is studied. It is found that S/(S + Se) compositional ratios of about 0.2 and 1 for wells and host material, respectively, and 50 wells with thicknesses in the range of 20–80 nm are able to promote solar cell efficiency. In particular, an increase in efficiency, short-circuit current density, and open-circuit voltage of 45.8%, 30.5%, and 10.7%, respectively, compared to the optimized device without nanostructures is expected.