Progress in Photovoltaics Research and Applications · 2013 · 158 citations · 31 references
EngineeringMaterials EngineeringMaterials ScienceElectronic MaterialsSemiconductor DevicesSemiconductor MaterialsElectrode MaterialsPhotovoltaic DevicesPhotovoltaic MaterialsRenewable Energy Power ConversionSemiconductor Device MaterialsSolar Cell MaterialsAbsorber MaterialsMaterial Microstructure EffectsSecondary Ion Mass SpectrometryThin-film Solar CellsTime-of-flight Secondary Ion Mass Spectrometry
The study aims to analyze device parameters from material microstructure and composition to enhance performance. Cu₂ZnSnSe₄ photovoltaic materials were fabricated by electrodepositing a metal stack followed by selenization, and the resulting CZTSe cell was compared to an electrodeposited CZTS cell. The electrodeposited CZTSe cell reached a record 7.0 % efficiency, the highest among such precursors, with an 18 ns minority carrier lifetime, while elevated oxygen levels and Sn‑rich grain boundaries were identified as major performance‑limiting factors, establishing a low‑cost baseline for future earth‑abundant solar cells. © 2013 John Wiley & Sons, Ltd.
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. Copyright © 2013 John Wiley & Sons, Ltd.
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