Nonlinearity effects in III–V multi-junction solar cells

In this work, methods and results of investigations of the nonlinear photocurrent rise in individual photoactive p-n junctions of multijunction solar cells in increasing the illumination intensity are presented. The main accent has been done on the investigation of the superlinear rise of the Ge subcell photocurrent. A theoretical model has been build-up to explain the reasons of superlinear rise of Ge subcell photocurrent with illumination intensity. It has been established that this rise is associated with saturation of nonradiative carrier recombination channels in the Ge subcell emitter and on ¿window-emitter¿ heterointerface and also with the secondary recombination radiation emitted from Ga(In)As subcell.