Cubic and orthorhombic SnS thin-film absorbers for tin sulfide solar cells

• Published in: Physica status solidi. A, Applications and materials science Vol. 213; no. 1; pp. 170 - 177
• Main Authors: Nair, P. K., Garcia-Angelmo, A. R., Nair, M. T. S.
• Format: Journal Article
• Language: English
• Published: Weinheim Blackwell Publishing Ltd 01-01-2016; Wiley Subscription Services, Inc
• Subjects: chemical deposition; Crystal structure; cubic SnS; Current density; orthorhombic SnS; Photovoltaic cells; Semiconductors; Solar cells; Solar energy; Sulfides; Thin films; Zinc
• ISSN: 1862-6300; 1862-6319
• DOI: 10.1002/pssa.201532426

The tin sulfide solar cell has acquired prominence in recent years. We present the characteristics of two polymorphs of SnS and their perspectives in thin‐film solar cells. Thin‐film SnS with cubic crystalline structure (SnS‐CUB) was obtained via two chemical routes. This semiconductor is distinct from the more common SnS thin films of orthorhombic crystalline structure (SnS‐ORT), also obtained by chemical routes. The SnS‐CUB reported here with a lattice constant a of 11.587 Å replaces the zinc blende structure previously reported for this material with a of 5.783 Å. Thin films of SnS‐CUB have an optical bandgap (Eg) of 1.66–1.72 eV and electrical conductivity (σ) of 10−6 Ω−1 cm−1. These characteristics distinguish them from SnS‐ORT presented here with an Eg of 1.1 eV and σ typically higher by two orders of magnitude. We discuss the uncertainties that have prevailed in the assignment of crystalline structure for SnS‐CUB and SnS‐ORT. The optical and electrical properties of these two polymorphs of SnS are contrasted in the context of light‐generated current density in solar cells. We conclude that the two SnS polymorphs when considered together as optical absorbers offer wider prospects for tin sulfide thin‐film solar cells.