Abstract
The use of multiple connected absorbing junctions (MJ-solar cells) is currently the best approach to maximize the efficiency of solar cells. Increasing the number of junctions leads to a larger theoretical efficiency. To achieve this requires the development of materials appropriate band gaps, which can be grown to a sufficient thickness to absorb light while current matched to other junctions and at the same time minimizing strain and defect generation by lattice matching. We report on modelling of the quaternary alloy GaAsBiN which has the potential to cover a wide range of band gaps below 1.42eV. In addition, this material can also be grown completely lattice matched onto GaAs or Ge with controllable band offsets which makes it very attractive for solar cell applications.