[19p-W541-1~14] Efficiency improvement for thin film compound semiconductor solar cells in the present and future

[19p-W541-7] Smart Stacked Heterogeneous Multijunction Solar Cells

〇Takeyoshi Sugaya¹, Kikuo Makita¹, Hidenori Mizuno¹, Ryuji Oshima¹, Takeshi Tayagaki¹ (1.AIST)

Keywords:multijunction solar cells,mechanically stacking

We have proposed a novel semiconductor bonding technology (smart stacking technology) for mechanically stacked multijunction solar cells by using conductive nanoparticle alignment with low bonding resistances and minimal optical absorption losses. This technique is very attractive for interconnecting different kinds of solar cells. We have demonstrated an InGaP(Eg-1.89 eV)/GaAs(Eg-1.42 eV)//InGaAsP(Eg-1.05 eV)/InGaAs(Eg-0.75 eV) 4-junction solar cell with a high efficiency of 31.6% under AM1.5. We also demonstrated an InGaP/GaAs/CIGS 3-junction solar cell with an efficiency of 24.2% for the first time. These results suggest that our stacking method is highly useful to realize the ultra-high efficiency (over 40%) multi-junction solar cells and various heterogeneous cell combinations, such as III-V, Si, and chalcogenide semiconductors. Moreover, the cost reduction can be expected because we can use inexpensive substrates for high efficiency III-V solar cells.