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Solar cells are used to convert energy of light into electricity. Currently several different designs are being used however the main challenge is to make the technology more widely used which means improving the performance of the devices while keeping cost down.
The example below shows how the combination of EDS, EBSD and EBIC can be used to characterise Cu(In,Ga)Se2 absorber layers. The aim is to understand why the photovoltaic performance of these solar cells is so high in spite of a large number of grain boundaries in the material. The general expectation is that grain boundaries have a negative effect on the photovoltaic performance. By using the EBSD and EBIC data it was possible to show that the type of grain boundary is important and it is not just a matter of density.
Data supplied by N Schäfer, Helmholtz-Zentrum, Berlin
The design is based on a structure of multiple oxide layers and the individual layer thicknesses have a significant effect on the photovoltaic performance of the device. This means that measuring and controlling the layer thicknesses is vital for ensuring the best performance. The example shows how this can be done in a non-destructive way by use of AZtec LayerProbe which is an approach for measuring thickness and compositions of multilayer structures.
(Left) An example structure of the all-oxide solar cell stack
(Right) Surface plots show the layer thickness obtained using LayerProbe of the TCO layer, the TiO2 layer and the CuxNiyOz layer respectively.
The Cu/Ni ratio is that in the CuxNiyOz layer
Solar energy conversion is part of a long term strategy to ensure a stable and adequate supply of electrical power in the future. Photovoltaics are the only method of converting sunlight directly into electrical energy. The efficiency of a photovoltaic system is measured...
Electron Beam Induced Current is a wellestablished analysis method of electrical activity in the SEM (and occasionally in the STEM). It provides a unique correlation of electrical and structural properties with very high spatial resolution.
Photovoltaic (PV) cells are an attractive option for generating low carbon renewable energy but traditional designs often include undesirable toxic compounds and must be manufactured under special conditions. The all-oxide approach to photovoltaic cells is thus very attractive...
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