Highly efficient and reliable mechanically stacked multi-junction solar cells using advanced bonding method with conductive nanoparticle alignments

This paper shows a high-efficiency mechanically stacked multi-junction solar cells using conductive nanoparticle alignments at the bonding interfaces. We fabricated a GaInP/GaAs/InGaAsP/InGaAs four-junction solar cell with the total efficiency of 30.4% under 1 sun AM1.5G. In addition, we discuss the reliability of our solar cells showing the results of accelerated aging test and thermal cycling test. It was confirmed that our solar cell has high long-term reliability under sever conditions (high and low temperature). Thus, our bonding method is promising to achieve highly efficient mechanically stacked multi-junction solar cells for practical use.