High-efficiency commercial grade 1cm2AlGaInP/GaAs/Ge solar cells with embedded InAs quantum dots for concentrator demonstration system

Triple-junction AlGaInP/InGaAs/Ge solar cells with embedded InAs quantum dots are presented, where typical samples obtain efficiencies of > 40% under AM1.5D illumination, over a range of concentrations of 2- to 800-suns (2 kW/m² to 800 kW/m²). Quantum efficiency measurements show that the embedded quantum dots improve the absorption of the middle subcell in the wavelength range of 900-940 nm, which in turn increases the overall operating current of the solar cell. These results are obtained with 1 cm² solar cells, and they demonstrate the solar cells' low series resistance, which and makes them ideal for the current generation in commercial concentrator systems. The thermal management and reliability of the solar cell and carrier is demonstrated by testing the experimental samples under flash (up to 1000-suns) solar simulator and continuous (up to 800-suns) solar simulator. Under continuous solar illumination, the solar cell temperature varies between ~Δ3°C at 260-suns linearly to ~Δ33°C at 784-suns when the solar cell is mounted with thermal paste, and ~Δ27°C at 264-suns linearly to ~Δ91°C at 785-suns when no thermal paste is used. The solar cells experience the expected shift in open circuit voltage and efficiency due to temperature, but otherwise operate normally for extended periods of time.