Structural, Electronic, and Optical Properties of Cu₂NiSnS₄: A Combined Experimental and Theoretical Study toward Photovoltaic Applications

Abstract

Earth-abundant quaternary chalcogenides are promising candidate materials for thin-film solar cells. Here we have synthesized Cu2NiSnS4 nanocrystals and thin films in a novel zincblende type cubic phase using a facile hot-injection method. The structural, electronic, and optical properties are studied using various experimental techniques, and the results are further corroborated within first-principles density functional theory based calculations. The estimated direct band gap ∼ 1.57 eV and high optical absorption coefficient ∼ 106 cm–1 indicate potential application in a low-cost thin-film solar cell. Further, the alignments for both conduction and valence bands are directly measured through cyclic voltametry. The 1.47 eV electrochemical gap and very small conduction band offset of −0.12 eV measured at the CNTS/CdS heterojunction are encouraging factors for the device. These results enable us to model carrier transport across the heterostructure interface. Finally, we have fabricated a CNTS solar cell device for the first time, with high open circuit voltage and fill factor. The results presented here should attract further studies.

One-step spray of Cu2NiSnS4 thin films as absorber materials for photovoltaic applications

“…And related to the XRD analysis, the band gap of 1.62 eV attributes to the CNTS phase and the second band gap of 2.06 eV can be correspond to Na 2 S phase (~ 2 eV) or to Cu 2 S phase (~ 2.37 eV) present in film [21,22]. To conclude, the CNTS band gap energy of 1.62 eV is near with the optimal values for solar cell applications reported by other authors [4,13,23].…”

Doping and alloying of kesterites

“…CNTS has an energy band gap of 1.5∼1.6 eV similar to CZTS and a high optical absorption coefficient of ∼10 6 cm −1 [142,[170][171][172][173][174]. CNTS exhibits the zincblende crystal structure while a complementary theoretical calculation predicts the P4̅ 2c polytype as the most thermodynamically stable phase [175]. Two solar cell architectures with CNTS have been reported: a device architecture glass/Mo/CNTS/CdS/Al-ZnO/Al yielded 0.09% efficiency [175] whereas another structure utilizing ZnS coated on ZnO nanorods in the ITO/ZnO-nanorods/ZnS/CNTS/Au architecture yielded 2.71% [176].…”

“…CNTS exhibits the zincblende crystal structure while a complementary theoretical calculation predicts the P4̅ 2c polytype as the most thermodynamically stable phase [175]. Two solar cell architectures with CNTS have been reported: a device architecture glass/Mo/CNTS/CdS/Al-ZnO/Al yielded 0.09% efficiency [175] whereas another structure utilizing ZnS coated on ZnO nanorods in the ITO/ZnO-nanorods/ZnS/CNTS/Au architecture yielded 2.71% [176]. It is not certain if the PV effect can be attributed to the CNTS absorber because comparable efficiencies were also obtained for Cu 2 FeSnS 4 and Cu 2 CoSnS 4 layers in the identical device structure.…”

Interface Structure and Band Alignment of CZTS/CdS Heterojunction: An Experimental and First-Principles DFT Investigation

“…where IP is the ionization potential [37]. Ferrocene was used as the internal reference E ref (4.5 eV vs NHE), and E peak-reduction and E peak-reduction energies corresponds to A1 and C1 peaks, respectively.…”