Design and optimization of 26.3% efficient perovskite/FeSi2 monolithic tandem solar cell

Abstract

A multijunction or tandem technique comprising a wide bandgap top cell and a narrow bandgap bottom cell may be a major stepping stone in an attempt to obtain high-efficiency solar cells. However, easier said than done, it takes a lot to correctly optimize the structure of all the involved layers so as to possibly obtain the desired results. In this paper, a perovskite (CH3NH3PbI3)/FeSi2 (p-i-n structure) 2-terminal (2-T) monolithic tandem solar cell is proposed and investigated using AFORS-HET v2.5 1D simulator. A hydrogenated amorphous silicon (a-Si:H)/hydrogenated microcrystalline silicon oxide (µc-Si1−xOx:H) tunnel recombination junction is employed to interconnect both perovskite and FeSi2 solar cell for current matching. The influence of both top and bottom absorber layer thickness is analyzed to optimize the device performance. The study reveals an optimized 26.3% efficient perovskite/FeSi2 monolithic tandem solar cell with JSC (21.4 mA cm−2), VOC (1.63 V), and FF (74.86%). The results in this paper suggest FeSi2 material with 0.87 eV bandgap as an alternative for narrow bandgap bottom cell for the perovskite-based tandem solar cells so as to obtain much higher efficiencies.