Fabrication of solar cells based on Cu₂ZnSnS₄prepared from Cu₂SnS₃synthesized using a novel chemical procedure

Abstract

Solar cells based on kesterite-type Cu2ZnSnS4 (CZTS) thin films were fabricated using a chemical route to prepare the CZTS films, consisting in sequential deposition of Cu2SnS3 (CTS) and ZnS thin films followed by annealing at 550 • C in nitrogen atmosphere. The CTS compound was prepared in a one-step process using a novel chemical procedure consisting of simultaneous precipitation of Cu2S and SnS2 performed by diffusion membranes assisted CBD (chemical bath deposition) technique. Diffusion membranes were used to optimize the kinetic growth through a moderate control of release of metal ions into the work solution. As the conditions for the formation in one step of the Cu2SnS3 compound have not yet been reported in literature, special emphasis was put on finding the parameters that allow growing the Cu2SnS3 thin films by simultaneous precipitation of Cu2S and SnS2. For that, we propose a methodology that includes numerical solution of the equilibrium equations that were established through a study of the chemical equilibrium of the system SnCl2, Na3C6H5O7·2H2O, CuCl2 and Na2S2O3·5H2O. The formation of thin films of CTS and CZTS free of secondary phases grown with a stoichiometry close to that corresponding to the Cu2SnS3 and Cu2ZnSnS4 phases, was verified through measurements of X-ray diffraction (XRD) and Raman spectroscopy. Solar cell with an efficiency of 4.2%, short circuit current of 16.2 mA/cm 2 and open-circuit voltage of 0.49 V was obtained.

Novel Chemical Route for Deposition of Cu2ZnSnS4 Photovoltaic Absorbers

“…This system also includes a pumping system and an electronic control proportional integral differential (PID) of the solution temperature. Details of the deposition system and of the possible reaction mechanism for the formation of the Cu 2 SnS 3 compound are given by Correa et al 14 The preparation of Cu 2 ZnSnS 4 films was achieved by sequential deposition of Cu 2 SnS 3 and ZnS films followed by annealing at 550 °C in sulfur ambient. The synthesis of the Cu 2 SnS 3 films was performed using the procedure described above and the ZnS films were deposited by conventional CBD method using a solution containing thiourea (CSN 2 30, 400 and 45 mM, respectively.…”

“…The ZnS layer was deposited by the conventional chemical bath deposition (CBD) method and the compound Cu 2 SnS 3 was grown in a onestep process using a novel chemical procedure which includes simultaneous precipitation of Cu 2 S and SnS 2 performed by diffusion membrane assisted CBD technique to achieve a moderate control of release of metal ions into the work solution, details are given by Correa et al 14 It is well known that in a CBD process, the controlled release of precursor ions to the work solution favors the ion by ion growth. 15 Therefore, we consider that a controlled release of ions achieved by the physical barrier provided by the diffusion membrane favors the growth ion by ion and prevents the cluster formation.…”

Zn(O,S) Buffer Layer Deposited by High Vapor Transport Deposition for Controlling Band Alignment of Cu2ZnSn(SxSe1−x)4 Thin‐Film Solar Cell Heterojunction

“…For the Cd-free buffer layer Zn(O,S)-based CZTSSe solar cells, the Zn(O,S) thin films with a thickness of about 50 nm were manufactured under different oxygen partial pressures and applied between the Al:ZnO and the CZTSSe absorber layers Ericson et al [39] Photochemical deposition CZTS 516 16.8 35 3.0 Zhang et al [40] Sulfurization CZTS 610 21.18 40 5.1 Yang et al [41] CBD CZTS 708 19.2 54 7.3 Huang et al [42] CBD CZTS 641 15.9 54 5.5 Correa et al [43] Sputtering CZTS 311 12.2 56 2.1 Kim et al [44] Modeling CZTS 640 23.9 65 10.0 Cherouana et al [18] CBD CZTSe 379 30.7 60 6.5 Neuschitzer et al [45] CBD CZTSe 336 25.0 51 5.0 Steirer et al [40] CBD CZTSe 358 33.5 60 7.2 Li et al [21] Sputtering CZGSSe 730 13.0 48 4.6 Schnabel et al [41] ALD CZTSSe 327 26.6 51 4.7 Hong et al [29] ALD CZTSSe 313 29.4 33 3.1 Hong et al [30] ALD CZTSSe 496 35.6 56 9.8 Jeong et al [46] ALD CZTSSe Barkhouse et al [47] CBD CZTSSe 389 29.0 52 5.8 Grenet et al [48] CBD CZTSSe 220 25.2 46 3.8 Park et al [49] CBD CZTSSe 400 21.8 51 4.5 Gao et al [50] CBD CZTSSe 388 22.8 42 3.7 Grenet et al [51] Modeling CZTSSe 640 24.1 41 6.3 Cherouana et al [18] CBD CZTSSe 596 15.4 49 4.5 Nguyen et al [52] HVTD CZTSSe 574 20.3 59 6.9 This work of the solar cells. To ensure statistical analysis, ten samples (0.25 cm 2 area) were processed for each process condition.…”

Effect of Sulfur Precursors on Crystallographic, Optical, and Electrical Properties of Cu2SnS3 Nanoparticles

“…) from sodium thiosulfate [45], and thiol (-SH) functional groups from the L-cysteine [46]. Thus, various Cu-Sn-S compounds are expected to be obtained.…”