Fabrication of Cu₂SnS₃ thin films by sulfurization of evaporated Cu‐Sn precursors for solar cells

Abstract

The ternary compound semiconductor Cu2SnS3 (CTS) is formed from non‐toxic materials that are abundant in Earth's crust and other low‐cost elements. CTS has also been reported to a band gap energy range of 0.93–1.77 eV and an absorption coefficient of 1.0×104 cm–1. Consequently, CTS is a potential material for the p‐type absorber layer of thin film solar cells. In this study, we examined the dependence of the optical, electrical and photovoltaic properties of CTS thin films on the Cu/Sn composition ratio. CTS thin films were fabricated by sulfurizing evaporated Cu‐Sn precursors with different Cu/Sn composition ratios at 560 °C for 2 h in a N2 atmosphere and sulfur vapor. The Cu/Sn composition ratios of the sulfurized films were determined to be 1.6–2.5 by X‐ray fluorescence. The solar cell comprising a CTS thin film with a Cu/Sn composition ratio of 1.77 exhibited the best performance among the cells examined, an open‐circuit voltage of 242 mV, a short‐circuit current density of 28.9 mA/cm2, a fill factor of 41.7% and a conversion efficiency of 2.92% were obtained. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Formation of copper tin sulfide films by pulsed laser deposition at 248 and 355 nm

“…Among the Cu-Sn-S compounds, Cu 2 SnS 3 (CTS) has been suggested as potential solar cell absorber because it has an absorption coefficient comparable to CZTS and a band gap of 0.9-1.35 eV depending on the crystal structure [4][5][6]. The highest efficiency of CTS solar cells of 4.65 % was achieved by thermal evaporation [7].…”

Pulsed laser deposition from ZnS and Cu2SnS3 multicomponent targets

“…In addition, the cubic phases of ZnS and Cu 2 SnS 3 are particularly hard to detect using X-ray diffraction within Cu 2 ZnSnS 4 , as the scattering peaks of all three compounds overlap [15]. Another interesting feature is that a pure absorber of Cu 2 SnS 3 can be used as a solar cell absorber, albeit with a low efficiency [16].…”

“…Cu 2 SnS 3 has previously been deposited as thin films by a variety of vacuum and non-vacuum methods including sulfurization of precursors produced by electron beam evaporation [16], sputtering [24], and electrodeposition [25] as well as, e.g., post-annealing of mixed elemental powders [26] and successive ionic layer absorption and reaction (SILAR) [27]. To our knowledge, Cu 2 SnS 3 has not previously been deposited by PLD.…”

Determination of band offsets at the Al:ZnO/Cu2SnS3 interface using X-ray photoelectron spectroscopy

“…4,5 Till now CTS solar cells have reached an efficiency of 2.92%. 6 Apart from solar cell, CTS is also used as a non-linear optical material, 7 low band gap semiconductor photodetector, 8 light emitting diodes and in photocatalysis. 9 Al: ZnO (AZO) with a wide band gap of 3.32 eV and a large transmittance of around 90% 10 is a good n-type window layer for solar cells.…”

“…CTS can been synthesized using several methods like co-evaporation, 6 sputtering 12 and electrodeposition 5 etc. These methods generally involve several steps and are prone to formation of secondary phases.…”