Electrodeposited Cu₂ZnSnSe₄ thin film solar cell with 7% power conversion efficiency

Abstract

High performance Cu 2 ZnSnSe 4 (CZTSe) photovoltaic materials were synthesized by electrodeposition of metal stack precursors followed by selenization. A champion solar cell with 7.0% efficiency is demonstrated. This is the highest efficiency among all of the CZTSe solar cells prepared from electrodeposited metallic precursors reported to-date. Device parameters are discussed from the perspective of material microstructure and composition in order to improve performance. In addition, a high performance electrodeposited CZTS (S only) solar cell was demonstrated and its device characteristics were compared against the CZTSe (Se only) cell. Using secondary ion mass spectrometry for the analysis of the chemical composition of the absorber layer, a higher concentration of oxygen in the electrodeposited absorber is thought to be the root cause of the lower performance of the electrodeposited CZTS or CZTSe solar cells with respect to a solar cell fabricated by evaporation. The grain boundary areas of Sn-rich composition are thought to be responsible for the lower shunt resistance commonly observed in CZTSe devices. We measured the longest minority carrier lifetime of 18 ns among all reported kesterite devices. This work builds a good baseline for obtaining higher efficiency earth-abundant solar cells, while it highlights electrodepositon as a low cost and feasible method for earth-abundant thin film solar cell fabrication.

Structural Evolution of Multilayer SnS/Cu/ZnS Stack to Phase-Pure Cu2ZnSnS4Thin Films by Thermal Processing

“…Solar cells with 5.5% and 7% efficiencies were reported with CZTS and CZTS/Se absorber layers developed by electrodeposition technique. 21,22 All these aforementioned results suggest a potential commercial interest behind sulfide/selenide based kesterite solar cells which need further optimization in the film synthesis and device fabrication steps to compete with established CdTe and CIGS technologies.…”

“…[17][18][19][20][21][22] Among the vaccum based techniques, co-evaporated Cu 2 ZnSnSe 4 (CZTSe) and sputter deposited CZTS have attained device efficiencies of 9.15% and 9.3% respectively. 18,19 The films developed with chemical methods such as electrodeposition and nanoparticle based suspension are equally competent and economically attractive.…”

High efficiency bifacial Cu2ZnSnSe4 thin-film solar cells on transparent conducting oxide glass substrates

“…1(e) and 1(f)). 16 From the top-down image in Fig. 1(c), the CZTSe layer on FTO is uniform and compact.…”

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

“…2 shows the XRD pattern of selenized film which mostly exhibited the peaks related to the Kesterite structure of CZTSe (JCPDS 00-052-0868), without having any significant reflections for any other compounds except those associated with bottom Mo layer and MoSe 2 . 18,19 Here, dominant peak of polycrystalline CTZSe (112) lies at diffraction angle (2θ) 28.53…”

“…[18][19][20][21] MoSe 2 (JCPDS 29-0914) which usually forms at the interface between CZTSe and bottom Mo layer was observed at diffraction angles 31.2…”