Hot-carrier effects in type II heterostructures

Hot-carrier solar cells have high theoretical limiting efficiency however, absorber materials with slow carrier thermalization remain a development barrier for these devices. In previous studies, charge separation in core-shell colloidal quantum dots has been shown to result in slow carrier relaxation. Charge separation also occurs in III-V heterostructures with type-II band alignments. We characterize hot-carrier effects in InAlAs/InP and InAlAs/InGaAsP quantum well structures, with type-II and quasi-type-II band alignments respectively. InGaAsP is identified as a promising hot-carrier absorber candidate, with thermalization coefficient 1.77±0.12 W.K-1.cm-2, corresponding to limiting solar conversion efficiency >42%, under 2000X.