Band-gap engineering of Cu2ZnSn1-xGe xS4 single crystals and influence of the surface properties
Thin film solar cells based on Cu2ZnSn(S,Se)4 are very promising, because they contain earth-abundant elements and show high absorptivity. However, the performance of these solar cells needs to be improved in order to reach efficiencies as high as that reported for Cu(In,Ga)Se 2-based devices. This...
| Autores: | , , , , , , , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2014 |
| País: | España |
| Institución: | Universidad Autónoma de Madrid |
| Repositorio: | Biblos-e Archivo. Repositorio Institucional de la UAM |
| Idioma: | inglés |
| OAI Identifier: | oai:repositorio.uam.es:10486/668736 |
| Acceso en línea: | http://hdl.handle.net/10486/668736 https://dx.doi.org/10.1016/j.actamat.2014.06.040 |
| Access Level: | acceso abierto |
| Palabra clave: | Germanium Kesterite Solar cells Spectroscopic ellipsometry Física |
| Sumario: | Thin film solar cells based on Cu2ZnSn(S,Se)4 are very promising, because they contain earth-abundant elements and show high absorptivity. However, the performance of these solar cells needs to be improved in order to reach efficiencies as high as that reported for Cu(In,Ga)Se 2-based devices. This study investigates the potential of band-gap engineering of Cu2ZnSn1-xGexS 4 single crystals grown by chemical vapour transport as a function of the [Ge]/([Sn] + [Ge]) atomic ratio. The fundamental band gap E0 is found to change from 1.59 to 1.94 eV when the Ge content is increased from x = 0.1 to x = 0.5, as determined from spectroscopic ellipsometry measurements. This knowledge opens a route to enhancing the performance of kesterite-based photovoltaic devices by a Ge-graded absorber layer. Furthermore, the formation of GeO2 on the surface of the as-grown samples was detected by X-ray photoelectron spectroscopy, having an important impact on the effective optical response of the material. This should be also taken into account when designing photovoltaic solar cells |
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