Investigation of the SnS Cu2ZnSnS4 Interfaces in Kesterite Thin Film Solar Cells

Kesterite Cu2ZnSnS4 CZTS , having only earth abundant elements, is a promising solar cell material. Nevertheless, the impact of the SnS secondary phase, which often forms alongside CZTS synthesis at high annealing temperature, on CZTS solar cells is poorly studied. We con amp; 64257;rm, by means of X ray di amp; 64256;raction, Raman scattering, and energy dispersive X ray spectroscopy mapping, that this phase tends to segregate at both the surface and the back side of annealed CZTS amp; 64257;lms with Cu poor and Zn rich composition. Using electron beam induced current measurements, it is further demonstrated that the formation of SnS on the CZTS surface is harmful for solar cells, whereas theSnS phase can be bene amp; 64257;cial for solar cells when it segregates on the CZTS rear. This positive contribution of SnS could stem from a passivation e amp; 64256;ect at the CZTS SnS rear interface. This work opens new possibilities for an alternative interface development for kesterite based photovoltaic technology