The use of III-V quantum heterostructures in PV: thermodynamic issues

Can the efficiency enhancement in (single photon) III-V multi-quantum well photovoltaic cells be explained without violating the second law of thermodynamics? In the first part of the paper we present and discuss a tentative solution of the problem. In the second part, the reduction of power losses associated to carrier thermalisation in high efficiency cells is discussed from the point of view of how to engineer the spectral properties of the radiation source. Particular attention is devoted to a thermodynamic model we have recently develop to explain the behaviour of a wide class of selective emitters for thermophotovoltaic applications.