Multi-stage photovoltaic devices with a cutoff wavelength of ∼3µm

Multi-stage Interband Cascade Photovoltaic (ICPV) devices with a room-temperature cutoff wavelength of ~3 μm were investigated. These devices were characterized at various temperatures under illumination from both a blackbody source and an interband cascade (IC) laser (emission wavelength of ~2.86 μm). Under laser illumination (8.0 W/cm²) an open-circuit voltage (V_oc) of 447 mV with a short-circuit current density (J_sc) of 1.5 A/cm² was obtained from a three-stage device at room temperature. Studies of size dependence with different devices found significant surface leakage current, resulting in low fill factors in these devices. These results suggest a great potential of ICPV devices to attain higher V_oc at lower J_sc compared to conventional single-absorber thermophotovoltaic (TPV) cells.