Structural and Electronic Properties of Cu₂MnSnS₄ from Experiment and First‐Principles Calculations

Abstract

Cu 2 MnSnS 4 shares several promising properties with the widely investigated Cu 2 ZnSnS 4 for photovoltaic applications such as containing only earth abundant and non-toxic elements, and suitable absorption characteristics for absorber materials. Thin film Cu 2 MnSnS 4 samples with various cation compositions are co-sputtered reactively followed by a high temperature anneal. Formation of Cu 2 MnSnS 4 and co-existence of several secondary phases is verified by XRD and Raman. Our investigation of the crystal structure based on first-principles DFT confirms that stannite crystal structure is preferred over kesterite, although, further verification considering cation disorder is needed. The direct band gap of Cu 2 MnSnS 4 is calculated as 1.52 eV (1.62 eV) for stannite (kesterite), which coincides with the range of the measured band gaps from spectrophotometry of 1.42-1.59 eV. After further annealing treatments below 240 C, the absorption shows reversible changes: the band gap blue-shifts and the Urbach tail energy is reduced. It is concluded that, just like Cu 2 ZnSnS 4 , disorder also occurs in Cu 2 MnSnS 4 . The implications of our findings are discussed and related to the current understanding of cation disorder in Cu 2 ZnSnS 4 and related compounds. Furthermore, for the first time first-principles DFT investigations are presented for the thiospinel Cu 2 MnSn 3 S 8 which is observed experimentally as a secondary phase in Sn-rich Cu 2 MnSnS 4 thin films.

Doping and alloying of kesterites

“…In terms of solar cell application, CMTS thin film is considered as absorber layer due to its similarly high absorption coefficient (>10 4 cm −1 ) [142]. The direct band-gap of CMTS was calculated to be 1.52 eV which coincides with the measured 1.42-1.59 eV [143]. From reversible annealing treatments it was also concluded that just like CZTS disorder also occurs in CMTS.…”

Calculation for High Pressure Behaviour of Potential Solar Cell Materials Cu2FeSnS4 and Cu2MnSnS4

“…The anti-ferromagnetic P 4 structure is 17 meV less stable than the anti-ferromagnetic ST phase at the PBE level. Our results on the relative KS and ST stability agree closely with PBEsol calculations by Scragg et al [32]. The same group has also carried out HSE06 calculations and found the ST structure to be more stable than the KS structure.…”

Effect of a Sulfur Precursor on the Hydrothermal Synthesis of Cu2MnSnS4

“…Furthermore, this phase-control mechanism can be expanded to other quaternary Cu 2 MSnS 4 (M = Cd 2+ , Mn 2+ ) nanocrystal syntheses, where the relative reactivity of M 2+ and the sulfur precursor plays a key role. Cu 2 MnSnS 4 (CMTS) has several promising properties in common with Cu 2 ZnSnS 4 , which has been extensively studied for photovoltaic applications since it contains only non-toxic Earth-abundant elements and appropriate absorption properties for absorber materials [13].…”

“…Therefore, it may be resistant to cation disorder, similar to the stannite Cu 2 FeSnS 4 . Liang et al describe the synthesis of stannite and wurtzite CMTS nanocrystals via a hot injection approach [13].…”