Design and characterization of InGaP-based InP quantum dot solar cells

Abstract

In an ideal intermediate-band (IB) concept, the host semiconductor generates current by absorbing short-wavelength light and the IB is used to absorb long-wavelength light. Here, we investigate the impact of the host absorber thickness at the front side of the cells on the properties of InGaP-based InP quantum dot (QD) solar cells. We prepared the InGaP-based InP QD cells with the front i-InGaP layer and compared them with the cells without the front i-InGaP layer. The insertion of the front i-InGaP layer results in an increase in quantum efficiency in the visible region, indicating that the short-wavelength light absorbed at the InGaP host increases the short-circuit current density in the cell. In addition, a thick host layer leads to reduced quantum efficiency below the host bandgap energy, which indicates that the thermal escape from QDs is suppressed. These results indicate that the optimization of the host semiconductor thickness is critical for achieving the ideal operation of the IB concept in the QD solar cells.