Electrochemical Studies of One-Step Electrodeposition of Cu-Sn-Zn Layers from Aqueous Electrolytes for Photovoltaic Applications

Abstract

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.

Novel Chemical Route for Deposition of Cu2ZnSnS4 Photovoltaic Absorbers

“…Several groups have reported the fabrication of CZTS thin films using a variety of methods such as sulfurization, electrodeposition, radio-frequency (RF) sputtering and co-evaporation. [5][6][7][8][9][10][11][12] Mitzi and co-workers 13 achieved a 12.7% efficient Cu 2 ZnSn(Se,S) 4 device fabricated from CZTSSe films prepared using a hydrazine-based pure solution approach and employing an In 2 S 3 /CdS double-emitter on CZTSSe absorbers upon annealing under optimized conditions.…”

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

“…Despite these limitations, reasonably successful film deposition and device fabrication have been demonstrated for both vacuum and solution-based deposition approaches. Several groups have reported the fabrication of CZTS thin films using a variety of methods such as sulfurization [8], electrodeposition [9,10] RF sputtering [11] and co-evaporation [2]. Kim et al achieved a 12,7% efficient Cu 2 ZnSn(Se,S) 4 device [12] fabricated from CZTSSe films prepared using a hydrazine-based pure solution approach and employing an In 2 S 3 /CdS double-emitter on CZTSSe absorbers upon annealing under optimized conditions.…”

Optimization of Cu2ZnSnS4 Absorber Layers via Sulfurization of Electrodeposited Cu-Zn-Sn Precursors for Photovoltaic Applications

“…Although there are various advantages and reports about the metal alloy deposition route, the efficiency of CZTS layers obtained by this method is still only ~3.4 %, which is ~ 5% lower than CZTS layers obtained through other electrochemical routes [78,84,87,89]. The low open circuit voltage observed in these CZTS materials is attributed to the presence of secondary phases and structural inhomogeneities, which arise from non-uniform compositional distribution [26,29,90].…”

“…Most of the studies on Cu-Zn-Sn metallic precursor layers used sodium citrate or pyrophosphate based solutions [74][75][76][77][78][79][80][81][82][83][84][85]. In these studies, deposition was carried out on Mo foil or Mo coated soda lime glass (SLG) substrates.…”

“…In this study, a layer consisting of CZT with columnar grains on Mo/SLG was obtained on a 0. 10 micrometer thickness, CZTSe layer achieved one of the highest efficiency of its class [87].…”