Close-spaced sublimation of SnS absorber layers and SnS/CdS heterojunction solar cells with Mo and Ti back metal contacts

Abstract

Tin sulfide is a promising semiconductor candidate to replace the currently used absorber materials in thin film photovoltaic such as Cu(In,Ga)(S,Se)2 and CdTe devices, which use toxic and scarce elements. However, numerous challenges still remain to approach comparable efficiencies for SnS-based solar cells. In this report, we address the following: (i) impact of growth conditions on phase purity and crystal quality of SnS thin films deposited by close-spaced vacuum sublimation technique; (ii) based on optimized SnS growth conditions, we further fabricate tin sulfide solar cells using traditional CdS buffer and i-ZnO/ZnO:Al bilayers and investigate the impact of molybdenum and titanium back metal contacts on photovoltaic parameters of resulting devices; (iii) finally, using device simulations, we reveal the impact of minority carrier lifetime in the SnS absorber and recombination velocity at the SnS/CdS heterointerface on solar cell parameters, demonstrating that these are the main factors affecting the performance of SnS-based photovoltaic devices.