In situ growth and characterization of Cu2ZnSnS4 thin films by reactive magnetron co-sputtering for solar cells

Abstract

Cu2ZnSnS4 (CZTS) thin films have been first in situ grown by reactive magnetron co-sputtering and its characterizations has been carried out by energy dispersive spectroscopy(EDS), X-ray diffraction(XRD), scan electron microscope(SEM), optical transmittance and electronic measurement. It was observed that the grown film shows homogeneous, compact surface morphology, and consists of large columnar grains throughout the thickness. The atom ratio Cu/(Zn+Sn) is about 1, while Zn/Sn is larger than 1 and decreases with the increase of substrate temperature. XRD analysis indicates that the grown film exhibits strong preferential orientation along (112) plane and the structural properties depend on growth temperature and Cu/(Zn+Sn) ratio. The in situ grown CZTS film has an optical absorption coefficient higher than 104 cm-1, and the optical band gap becomes narrow with the increase of substrate temperature and achieves (1.51±0.01)eV at 500℃. The conduction type of the CZTS films is p-type and the value of carrier concentration is comparable with values of device quality CIGS.

First-Principles Study on Electronic and Optical Properties of Kesterite and Stannite Cu₂ZnSnS₄ Photovoltaic Absorbers

“…The valence band maximum is taken as the zero of energy. Because the GGA results in a well-known underestimation of the band gap due to the underestimation of conduction band state energies, the band gap is corrected with a scissors operator according to the experimental data [6,23]. The values of band gaps are 1.50 eV for KS CZTS, and 1.45 eV for ST CZTS.…”

Preparing Cu2ZnSnS4films using the co-electro-deposition method with ionic liquids

“…The CuZnSnS 4 (CZTS)-based solar cell is currently considered to be one of the next-generation thin-film solar cells because it is free from scarce and toxic elements and has reduced cost for mass production. [1,2] It is known that CZTS has a direct bandgap between 1.45 eV and 1.6 eV and an absorption coefficient of 10 4 cm −1 in the visible light range. Recently, CZTS solar cells have been reported to achieve a conversion efficiency of 6.7% by using a cosputtering process followed by annealing in H 2 S. [3] For a CZTS-or copper indium gallium selenide (CIGS)based solar cell, two advances are very important: one is the introduction of the non-vacuum deposition system, and the other the development of a way to conveniently control the element molar ratios to avoid the formation of the secondary phase.…”