Hot carrier effects in the collection efficiency of solar cells: a-Si:H

Abstract

Recent models for the falloff in spectral response at short wavelengths in low mobility solar cell materials have been based upon the diffusion of thermalized carriers against the electric field to high recombination contacts or interfaces. These models neglect the excess energy imparted to the carriers by short wavelength light, that enable them to easily move against the field while thermalizing. Calculations of the distance the carriers diffuse before losing their excess energy by phonon emission indicate that in the high absorption coefficient region of a-Si:H up to 50% of the carriers can reach a contact or interface before thermalizing.