Current status of n-type SnS: paving the way for SnS homojunction solar cells

Abstract

Orthorhombic SnS is a promising thin-film solar-cell material composed of safe and abundant elements with suitable optical properties for photovoltaic application. For approximately two decades, SnS solar cells have employed heterojunction structures with p-type SnS and other n-type semiconductors because undoped SnS typically exhibits p-type electrical conduction. However, their conversion efficiency has remained stagnant at 4–5% for a long time. A breakthrough is required to significantly improve their conversion efficiencies before SnS solar cells can be put into practical use. Therefore, this comprehensive review article establishes the current state of the art in SnS solar cells, with an aim to accelerate both fundamental research and practical applications in this field. We discuss issues specific to SnS heterojunction solar cells, the advantages of the homojunction structure, and summarize recent advances in the n-type conversion of SnS by impurity doping, which is required to form a homojunction. The latter half of this article describes the latest research on the fabrication of n-type single crystals and films of halogen-doped n-type SnS, which is prepared via a doping system suitable for practical use. We conclude the article by summarizing the current status and future work on SnS homojunction devices, including the development of high-efficiency multi-junction SnS solar cells by band gap engineering.

Extent of dependence of crystalline, morphological, optical and electrical properties on deposition time of sprayed SnS thin films

“…Tin sulfide material is a promising semiconductor; it has two stable SnS and SnS 2 phases. Both phases are promising alternatives for absorber layer use in thin film SnS homojunction and heterojunction solar cells (Suzuki et al, 2022), holographic recording system in gas sensors and recently as a novel material for electrodes in lithium ions batteries (Cho et al, 2019; Jiang et al, 1998; Momma et al, 2001). SnS semiconductor is characterized by a high absorption coefficient (α ∼ 10 5 cm −1 ) (Koteeswara Reddy & Ramakrishna Reddy, 2007; Nisha, Kumar, et al, 2022), a direct band gap lying between 1.3 and 1.5 eV (Sun et al, 2012) and is composed with abundant non‐toxic and cheap elements (Engelken et al, 1987).…”

Experimental Identification of Atomic Orbital Contributions to SnS Valence Band using Polarization‐Dependent Angle‐Resolved Photoemission Spectroscopy

“…[4] Thus, despite recent advances made in computational science, experimental approaches can still provide important information for understanding the electronic structures of materials. In this study, tin sulfide (α-SnS, whose crystal structure is shown in Figure S1 in Supporting Information), which is a promising material for thin-film solar cells [5,6] and thermoelectric materials, [7] was used as a model material for angle-resolved photoelectron spectroscopy (ARPES) analysis. ARPES is the only experimental technique that enables the direct observation of the band dispersion based on measurements of both the energy and momentum of electrons in a material.…”

Defect pairing in Fe-doped SnS van der Waals crystals: a photoemission and scanning tunneling microscopy study

“…for efficient solar cells, several works address the implementation of guest atoms into the SnS structure with the aim to push the carrier into the n-doped regime (see ref. 6 and references therein). In addition, the implementation of magnetic guests atoms is a standard approach to introduce spin degrees of freedom into semiconductors.…”