III‐V//Si multijunction solar cells with 30% efficiency using smart stack technology with Pd nanoparticle array

Abstract

Multijunction (MJ) solar cells achieve very high efficiencies by effectively utilizing the entire solar spectrum. Previously, we constructed a III‐V//Si MJ solar cell using the smart stack technology, a unique mechanical stacking technology with Pd nanoparticle array. In this study, we fabricated an InGaP/AlGaAs//Si three‐junction solar cell with an efficiency of 30.8% under AM 1.5G solar spectrum illumination. This efficiency is considerably higher than our previous result (25.1%). The superior performance was achieved by optimizing the structure of the upper GaAs‐based cell and employing a tunnel oxide passivated contact Si cell. Furthermore, we examined the low solar concentration performance of the device and obtained a maximum efficiency of 32.6% at 5.5 suns. This performance is sufficient for realistic low concentration photovoltaic applications (below 10 suns). In addition, we characterize the reliability of the InGaP/AlGaAs//Si three‐junction solar cell with a damp heat test (85 °C and 85% humidity for 1000 h). It was confirmed that our solar cells have high long‐term stability under severe conditions. The results demonstrate the potential of GaAs//Si MJ solar cells as next‐generation photovoltaic cells and the effectiveness of smart stack technology in fabricating multijunction cells.

Two‐Terminal Direct Wafer‐Bonded GaInP/AlGaAs//Si Triple‐Junction Solar Cell with AM1.5g Efficiency of 34.1%

“…Different technologies including glueing, "smart stacking," and direct wafer bonding have been realized. [9][10][11] Here, the highest efficiencies have been demonstrated: 35.9% in a four-terminal configuration. [10] For the more industrially relevant two-terminal configuration which can serve as a direct drop-in replacement for standard single-junction Si solar cells, an efficiency of 33.3% was reached previously.…”

A Brief Review of High Efficiency III-V Solar Cells for Space Application

“…This problem can be solved by adding a tunnel junction between the subcells [66]. The 30% conversion efficiency of III-V//Si multi-junction solar cells using smart stack technology have been reported [67]. A schematic diagram of InGaP/AlGaAs//Si triple-junction solar cell is shown in Figure 1B.…”

“…FIGURE 1 | (A)The structure of GaInNAs device grown by MOVPE with dimethylhydrazine as the nitrogen source[50]; (B) The structure of InGaP/AlGaAs//Si triplejunction solar cell[67].…”

III‐V//CuxIn1−yGaySe2 multijunction solar cells with 27.2% efficiency fabricated using modified smart stack technology with Pd nanoparticle array and adhesive material

“…For these methods, “smart stack” is an integration of conductive Pd nanoparticle domain for the bonding interface, which contributes to minimizing the bonding resistivity and optical loss. Using smart stacking technology, we attained an efficiency of 30.4% for an InGaP/GaAs//Si three‐junction solar cell 40 …”

“…Using smart stacking technology, we attained an efficiency of 30.4% for an InGaP/GaAs//Si three-junction solar cell. 40 In addition, we recently reported on a GaAs//Cu x In 1Ày Ga y Se 2based MJ solar cell. [41][42][43] The Cu x In 1Ày Ga y Se 2 cell (hereinafter, CIGSe)…”