Effect of tunnel junction on the indium gallium nitride multi-junction tandem solar cell performances

During the past few years a great variety of multi-junction solar cells has been developed with the aim of a further increase in efficiency beyond the limits of single junction devices. InxGal-xN is one of a few alloys that can meet this key requirement. While in mechanically stacked multi-junction (MJ) cells the subcells usually have separate contacts, monolithic MJ cells are epitaxial grown on one substrate and the sub cells are interconnected in series by tunnel diodes leading to a standard two-terminal contact. This paper describes the role of the tunnel junction's in InGaN tandem solar cells. Two tandem solar cells the InxGal-xN / InxGal-xN the firs without tunnel junction and second with tunnel junction InxGal-xN are selected for simulate the overall characteristics of the AMPS-1D. Our calculation shows that the efficiency can be improved from 17% for a tandem solar cell without tunnel junction up to 23.21% for a tandem solar cell with tunnel junction obtained in 1-sun AM1.5 illumination and at room temperature, using realistic material parameters. (C) 2017 The Authors. Published by Elsevier Ltd.