74.7% Efficient GaAs-Based Laser Power Converters at 808 nm at 150 K

High-efficiency multijunction laser power converters are demonstrated for low temperature applications with an optical input at 808 nm. The photovoltaic converting III-V semiconductor devices designed GaAs absorbing layers, here 5 thin subcells (PT5), connected by transparent tunnel junctions. Unprecedented conversion efficiencies of up to 74.7% measured temperatures around 150 K. At 77 K, a remarkably bandgap offset value Woc = 71 mV is obtained intensity ~7 W/cm2. the PT5 retains efficiency 65% 0.3 W converted output power.