Fundamental Aspects of Hot Carrier Solar Cell Operation

The hot carrier solar is a novel photovoltaic concept for exceeding the conventional single band gap limit by reducing thermalization losses. Whilst there are reports of having observed hot carrier based solar power conversion, the performances reported lag well behind the promised limits. In this report we examine the operation of a hot carrier solar cell at its most fundamental level. The extraction process and its impacts on limiting efficiency are examined for the case of a zero band gap absorber with thermionic barriers as the energy selective contacts, with it shown that a heat flow from the absorber to the contact layer is present at open circuit voltage. The operation of this type of hot carrier solar cell is examined for forward bias in the dark, showing marked differences with expected current voltage characteristics for conventional solar cells The impact of carrier cooling, with heat transferred from the carriers to the lattice is investigated for both the dark and illuminated cases.