The influence of tunneling effects on the efficiency of heterojunction solar cells

A theoretical model is developed which presents the transport properties through the space charge region of ap ⁺ n heterojunction solar cell, whereby not only recombination through interface states but also tunneling through potential barriers is taken into account. It is investigated whether tunneling can give rise to optimum heterojunction structures which have better efficiencies that without tunneling. It is found that only if the strongly doped semiconductor has an optimum bandgap and the weakly doped semiconductor a larger bandgap, tunneling can make the structure optimum. In all other cases of optimum structures, tunneling deteriorates the efficiency. Work supported by the Energy R. D. programmes of the Commission of European Communities and the Belgian Ministry of Science.