Recent results on quantum well solar cells

This review starts with the modelling of dark-currents in lattice-matched quantum well cells. We discuss an unexpected result obtained by extending studies of radiative recombination in single wells in the dark to light biased measurements. New results are reported on strain-balanced cells. In shallow wells the short-circuit current increases linearly with well number, whereas the dark-current increases sub-linearly. This results in a 50 shallow quantum well device having a higher efficiency than a p-n control cell. Ideality n = 1 behaviour is observed at concentrator currents. The intercept of this dark current contribution varies less with absorption threshold than expected. Preliminary results indicate that a 50 well cell maintains a higher efficiency than a comparable p-n cell up to 100x concentration. Calculations suggest that a 50 well cell would enhance a GaInP/GaAs tandem cell from 33% to 37% efficiency at 300x concentration.