Benefits of Double Bandgap Grading for Highly Efficient Cu(In,Ga)(Se,S)2 Thin Film Solar Cells
| Autor: | Lavrenko, T., Ott, T., Walter, T. |
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| Jazyk: | angličtina |
| Rok vydání: | 2014 |
| Předmět: | |
| DOI: | 10.4229/eupvsec20142014-3dv.2.4 |
| Popis: | 29th European Photovoltaic Solar Energy Conference and Exhibition; 1781-1785 Unique material properties of CIGS solar cells brought this technology to the lead, demonstrating the highest efficiencies compared to other thin film counterparts. [1] Double bandgap grading due to sulphur incorporation into the surface of Cu(In,Ga)(Se,S)2 absorbers and a high Ga content at the back contact can be also viewed as an important contributor with respect to such high performance. This paper is focused on the impact of a sulphurization step on the bandgap in the space charge region and its ability to separate the absorption and recombination processes maintaining both high open circuit voltages and short circuit currents at the same time. Moreover, an accumulation of Ga at the absorber / back contact interface is discussed with regard to a back contact passivation and suppression of the phototransistor effects often observed at low temperatures. In order to explain and verify this model SCAPS simulations will be presented and compared to the experimental results. Furthermore, it will be shown that gallium due to high temperature deposition processes diffuses from the back contact towards the principal pn-junction resulting in a more homogeneous distribution within the absorber layer and modifying both optical and electrical properties of solar cells. |
| Databáze: | OpenAIRE |
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