Intermediate Band Challenge in InAs/GaAs Quantum Dot Solar Cell at Cryogenic Temperatures

The temperature dependence of the photoluminescence from InAs/GaAs quantum dot solar cell (QDSC) is studied. A modified on-resonance z-scan measurement technique is used to extract the quantum dot saturation intensity from room temperature to 170K. The saturation intensity appreciably decreases when the temperature is decreased but is still comparable to the sun intensity at maximum concentration at 170 K. This implies that the energy conversion efficiency of this QDSC, even at 170 K, cannot be enhanced by invoking the concept of an intermediate band solar cell.