Universidad Politécnica de Madrid

Instituto de energía solar

R&D at IES

Flat plate photovoltaics beyond silicon

Silicon solar cells account for more than 90% of the PV power installed in the world. However, their efficiency is approaching the theoretical limits and therefore further improvements will require a breakthrough in device architectures. In this context, we are investigating III-V on silicon multijunction solar cells (see Figure 1). In our approach, a GaAsP (1.7eV) top cell partners with a Si (1.1eV) bottom cell to form a dual-junction solar cell with a theoretical efficiency limit in excess of 40%. The challenges needed to engineer such a device like are manifold. To start with, there is the need to create a high quality III-V nucleation layer on silicon to serve as the template for further III-V growth. To this end, we are investigating the MOVPE growth of GaP layers on Si in a single reactor process (see figure 2). In parallel, we are also working towards defining ways to manufacture these hybrid solar cells taking the most of III-Vs and Si. Although the processing of conventional Si solar cells is a well-known technology, certain high temperature steps have been found to be incompatible with III-V semiconductors. Accordingly, we are searching for innovative low-temperature high-end processing alternatives.

Contact person: Dr. Ignacio Rey-Stolle


Selected publications

  1. García-Tabarés, E., Carlin, J. A., Grassman, T. J., Martín, D., Rey-Stolle, I., and Ringel, S. A., “Evolution of silicon bulk lifetime during III–V-on-Si multijunction solar cell epitaxial growth”,  Progess in Photovoltaics: Research & Applications, 24: 634–644 (2016) (http://dx.doi.org/10.1002/pip.2703)

  2. D. Martín-Martín; E. García-Tabarés; I. Rey-Stolle, “Assessment of Rear-Surface Processing Strategies for III–V on Si Multijunction Solar Cells Based on Numerical Simulations”, IEEE Transactions on Electron Devices, Vol. 63, No: 1, pp: 252 – 258 (2016) (http://dx.doi.org/10.1109/TED.2015.2498527)

  3. E. García-Tabarés, I. Rey-Stolle, “Impact of metal-organic vapor phase epitaxy environment on silicon bulk lifetime for III–V-on-Si multijunction solar cells”, Solar Energy Materials and Solar Cells, Vol. 124, pp.17–23 (2014 ) (http://dx.doi.org/10.1016/j.solmat.2014.01.034)

  4. E. Garcia-Tabares, I. Rey-Stolle, and D. Martin, "Optimizing diffusion, morphology and minority carrier lifetime in Silicon for GaAsP/Si dual-junction solar cells”, in 10th Spanish Conference on Electron Devices (CDE), 2015 Aranjuez, 2015, pp. 1-4. (http://dx.doi.org/10.1109/CDE.2015.7087512)

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