We report progress in developing optimized diffraction gratings for coupling solar radiation from the airmass 0 spectrum
into waveguide modes of ultrathin quantum dot solar cells (QDSCs). Electromagnetic simulations have been used to
optimize the grating geometry and to analyze the nature of diffraction within the device structure. These results suggest
that increases in photocurrent of over 100% at wavelengths of QD absorption, corresponding to over 10% improvement
in short-circuit current, can be achieved in optimal ultrathin devices by incorporating gratings in the rear contact.