Comparison of bulk material candidates for hot carrier absorber

We investigated four hot carrier (HC) absorber material candidates InN, BSb, InP and AlSb for HC solar cells. Their potential of making good absorbers was estimated based on available experimental data from literature and theoretical results from high accuracy density functional theory calculations. For a comprehensive assessment of HC thermalization, we developed a new method to quantify HC cooling powers in these materials. Contrary to common belief, our results show that a minimum optical frequency higher than twice the maximum acoustical frequency is not vital for HC absorber materials. For materials with highly polar bonds, Ridley decay triggers significant thermalization, compromising the usefulness of certain HC absorber candidates such as InN.