Advances in low-cost and nontoxic materials based solar cell devices

Photovoltaics (PV) have become increasingly popular and reached as the third-largest renewable energy source. Thin-film solar cells made from earth-abundant, inexpensive and environmentally friendly materials are needed to replace the current PV technologies whose large-scale applications are limited by material and/or resource constraints. Near optimum direct optical bandgap of 1.3 eV, high absorption coefficient (>10⁴ cm⁻¹), less toxic, and abundant raw resources along with considerable scalability have made tin sulfide (SnS) as a strategic choice for next-generation PVs. In this review, limitations of leading commercial PV technologies and the status of a few alternate low-cost PV materials are outlined. Recent literature on crucial physical properties of SnS thin-films and the present status of SnS thin-film-based solar cells are discussed. Deficiency and adequacy of some of the key properties of SnS including carrier mobility (μ), minority carrier lifetime (τ), and absorption coefficient (α) are discussed in comparison of existing commercial solar cell materials. Future research trends on SnS based solar cells to enhance their conversion efficiencies towards the theoretical maximum of 24% from present ~5% and its prospectus as next-generation solar cell is also discussed.