**Author details**

To study the GaAs/GaInNAs SLSC performance, it was considered a cluster composed of ten variably spaced multiple quantum wells optimized to maximise the resonant tunneling between adjacent wells. The GaInNAs quantum wells contains of 1% nitrogen composition and the GaAs barriers are 1 nm wide. A series of clusters are inserted in the intrisic region, independent from each other, in such a way that there is no coupling between neighboring

Figure 16 exhibits a contour plot of the conversion efficiency for the SLSC as a function of the cluster width and the number. If we compare these results with Figure 15 is evidenced that maximum SLSC conversion efficiencies are higher than those of QWSC by 3%. The AB contour in Figure 16 represents highest conversion efficiency obtained in the calculations. It can be also evidenced that the conversion efficiency rises as the width and the number cluster

A model for quantum well and superlattice solar cells was presented and applied to theoretically study qualitative trends in quantum well and superlattice solar cell performances. The findings from this study enhance our understanding of these devices and could provide a suitable guide for its designing. The model allows optimization the solar cell performance as a function of several of its parameters. The well and barrier band gaps, the width and depth of the wells, the amount of the wells in the intrinsic region are

We have shown theoretically that the insertion of multiple quantum wells into the intrinsic region of a p-i-n *AlxGa*1−*xAs* solar cell can enhance the conversion efficiency compared with its baseline cell. The quantum efficiency and the photocurrent for the AlGaAs/GaAs QWSC was calculated and compared with experimental results obtaining good agreement. These results, together with the agreement of the calculated open-circuit voltage with experimental

GaAsP/InGaAs/GaAs strain-balanced solar cell was presented and studied. The effect of the electric field and the tensile and compressive stress, were carefully considered. The results of the modeling of SB-QWSC were also compared with experimental measurements successfully, validating again the suitability of the model. Following the model was used to determine the highest possible efficiencies for SB-QWSC containing quantum wells under varying degrees of strain. The strain-balanced multiple quantum well solar cells show a high conversion efficiency that makes it very attractive for their use in multijunction solar cells for space applications or concentrator photovoltaics based on a GaAsP/InGaAs/GaAs middle cell. Solar cells containing strain balanced QWs in a multijunction solar cell allow the

We have shown a new type of photovoltaic device, the superlattice solar cell (SLSC), where coupled quantum wells or superlattices are inserted into the intrinsic region. The aim of this approach is the possibility of better tailor the photon absorption improving, at the same time, the transport of photogenerated carriers due to the tunneling along the nanostructure. The model adjusted to the superlattice solar cell case was then applied to GaAs/AlGaAs and GaAs/GaInNAs material systems. For the GaAs/AlGaAs case, was found photocurrent increase, and slight increments in the conversion efficiency over the QWSC. When applied the

clusters.

176 Solar Cells - New Approaches and Reviews

**4. Conclusions**

also increase, due to higher photon absorption.

considered in the model to attain the best conversion efficiency.

values confirm the reliability of the model presented in this chapter.

absorption edge of each subcell to be independently adjusted.

Luis M. Hernández1, Armando Contreras-Solorio2, Agustín Enciso2, Carlos I. Cabrera2, Maykel Courel3, James P. Connolly4 and Julio C. Rimada5<sup>∗</sup>

\*Address all correspondence to: jcrimada@fisica.uh.cu; jcrimada@gmail.com

1 Faculty of Physics, University of Havana, Colina Universitaria, La Habana, Cuba

2 Academic Unit of Physics, Autonomous University of Zacatecas, Zacatecas, Mexico

3 Higher School in Physics and Mathematics, National Polytechnic Institute, Mexico, Mexico

4 Nanophotonics Technology Center, Polytechnic University of Valencia, Valencia, Spain

5 PV Laboratory, Institute of Materials Science and Technology (IMRE)- Faculty of Physics, University of Havana, La Habana, Cuba
