Solar cell efficiency

Efficiency of solar cells could rise after the discovery of indium nitride having only 0.7eV band gap instead of 2.0eV. See Phys. Rev. B, 66, 201403, 2002. As of 2002, the efficiency of solar cells were 35% compared to the theoretical limit of 70%. By having a smaller band gap, it can absorb the light which is less energetic. By stacking various different band gap materials, the solar cell can absorb a greater range of energetic light.