Co-Electrodeposition of Metallic Precursors for the Fabrication of CZTSe Thin Films Solar Cells on Flexible Mo Foil

Abstract

Earth abundant Cu 2 ZnSnSe 4 (CZTSe) thin films solar cells were fabricated on flexible molybdenum (Mo) foil substrate through an electrochemical approach. After co-electroplating from single electrolyte, Cu-Zn-Sn (CZT) precursor was selenized in quartz tube furnace at 550 • C for 15 minutes in Ar atmosphere with the presence of elemental selenium in order to form CZTSe compound. Before selenization, CZT precursor was soft-annealed at 310 • C for 150 minutes in Ar atmosphere in order to improve intermixing of the elements and to reduce roughness. The formation of Kesterite CZTSe on selenized film was confirmed by X-ray diffraction (XRD) and Raman spectroscopy. SEM imaging and EDS line profile on the cross-section of CZTSe layer showed the well-formed CZTSe along depth of the film also. Opto-electrical characteristics of the film by photoluminescence spectroscopy confirmed the suitability of the absorber layer to make solar cell. A flexible solar cell with Al/Al-ZnO/i-ZnO/CdS/CZTSe/Mo-foil configuration, which showed 0.1% power conversion efficiency at first attempt, has been fabricated, in which buffer layer CdS has been deposited through chemical bath deposition and transparent conducting oxides (i-ZnO, Al-ZnO) have been deposited by DC pulsed sputtering. Thin films solar cells based on earth abundant Kesterite Cu 2 ZnSn(S,Se) 4 absorber layers have drawn significant attention within the research community over the last few years as future low cost photovoltaic devices in order to meet global energy demand in tera-watt scale. These materials are direct bandgap p-type semiconductors for which the bandgap ranges from 1.0 eV for Cu 2 ZnSnSe 4 (CZTSe) to 1.5 eV for Cu 2 ZnSnS 4 (CZTS) and at the same time they have very high optical absorption coefficients of over 10 4 cm −1 which make them potential alternative as absorber layer for existing commercialized thin films solar cells Cu 2 InGaSe 4 (CIGS) and CdTe.1 As CIGS and CdTe contain earth scarce, costly and toxic materials, so they need to be replaced. Different vacuum and non-vacuum techniques have already been employed to fabricate high quality crystalline Kesterite compounds. Up to now, highest 12.6% power conversion efficiency of sulfo-selenide Cu 2 ZnSn(S,Se) 4 thin film solar cell was achieved using hydrazine based solution process. 2 Whereas highest power conversion efficiencies of pure sulfide CZTS (obtained from evaporation) and pure selenide CZTSe (obtained from sputtering) thin film solar cells are 9.2% and 11.6% respectively reported.3,4 Those highest power conversion efficiencies were achieved when conventional molybdenum (Mo) coated soda lime glass was used as a back contact substrate. On the other hand, till now highest power conversion efficiencies of CZTS and CZTSe thin film solar cells on flexible substrate were reported 4.2% and 6.1%. 5,6 In order to reduce production costs and deployment of thin film PV-based technologies in mass scale, Kesterite-based thin film solar cells technologies should be manufacturable at high throughput with low cos...

CZTS thin film solar cells on flexible Molybdenum foil by electrodeposition-annealing route

“…Most of the Kesterites-based thin films solar cells have been fabricated till now on typical Mo-coated soda lime glass (SLG). There are only few reports on fabrication of Kesterites-based solar cells on the flexible substrate like metallic foils or polyimides, irrespective to the fabrication processes [16][17][18][19][20][21][22][23][24]. Fabrication of Kesterites-based thin film solar cells on the flexible substrate has huge potential in order to minimize production cost due to roll-to-roll manufacturing on the flexible substrate which enables the use of compact size deposition equipment with high throughput [25].…”

Co‐Electrodeposited Cu2ZnSnS4 Thin Film Solar Cell and Cu2ZnSnS4 Solar Cell – BiVO4 Tandem Device for Unbiased Solar Water Splitting

“…Electrodeposition of metallic precursors followed by high temperature sulfurization is already well proven to be one of the best ways to fabricate a high‐quality CZTS layer. This approach can be further subdivided into two categories: (A) electrodeposited multilayer metallic stacked layers and (B) co‐electrodeposited mixed elemental precursors . Type (A) is a popular approach that has been abundantly studied before.…”

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

“…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.…”