In the years to come, electricity production is bound to increase, and Cu2ZnSn(S, Se)4 (CZTS) compounds, due to their suitability to thin-film solar cells, could be a means to fulfill the demand. After explaining the reasons of the sudden interest of the CIGS scientific community for CZTS solar cells, this paper reviews recent papers published on the subject of kësterites-based solar cells. After a description of crystallographic and optoelectronic properties, including CZTS crystalline structure, defect formation and metal composition, this review paper focuses on CZTS synthesis processes and device properties. Synthesis strategies, including one-or two-step processes, deposition temperature, binary formation control via atmosphere control and their effect on device properties are discussed.

Copper, tin and zinc have been co-electrodeposited on Mo-coated glass substrates from an aqueous acid sulfate solution at room temperature with the aim of preparing kesterite absorber layers for solar devices. The solution contains copper, tin and zinc sulfate, potassium sulfate and sodium citrate at pH = 4.75. The effect of two complexing agents (sodium citrate and tartaric acid) is characterized by solution chemistry analysis, by voltammetry using a rotating disk electrode and an electrochemical quartz crystal microbalance. A deposition process is developed to co-deposit the three metals with the appropriate composition (copper poor and zinc rich). Deposition kinetics has been investigated. The composition can be tuned by mass transport control and by deposition potential. Composition, morphology and structure are characterized by Inductively Coupled Plasma analysis, Energy Dispersive X-ray Spectrometry coupled to Field Emission Scanning Electron Microscopy and X-ray Diffraction. The co-deposited layers are porous due to dendritic growth. After annealing at 530°C during 15 min in a selenium atmosphere, a 5.8% solar cell efficiency has been obtained.

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