Hot-carrier generation in a solar cell containing InAs/GaAs quantum-dot superlattices as a light absorber

We demonstrated hot-carrier (HC) effects in a solar cell containing InAs/GaAs quantum-dot superlattices (QDSLs) functioning as a light absorber at low temperature. The band edge of the GaAs can energetically select HCs created in the QDSL. The short-circuit current density increases almost linearly with the incident photon density under below-bandgap excitation, suggesting that nonlinear processes such as saturable absorption are negligible. The short-circuit current and the open-circuit voltage of the QDSL solar cell show step-wise changes as a function of the excitation density because of state filling.