ABSTRACT
Authors also describe the physical constraints of the phenomenon of luminescent refrigeration based on the fact that the radiative emission of a biased semiconductor can be applied to remove heat in the form of photons. Finally, the authors discuss the application of the reciprocity relation on an organic solar cell where light absorption is associated with the charge-transfer between different materials. When the charge separation steps that produce fresh electrons and holes in the respective energy levels have been realized, we obtain an ensemble of free charge carriers in the semiconductor, or in separate phases, where they are mobile. Since these are excess populations of electrons and holes with respect to the equilibrium situation, the authors have formed a situation of separation of Fermi levels and the recombination process starts immediately, while the continuous absorption of photons produces a renewed supply of free electronic carriers.
