计算太阳能电池的极限效率。

The generalised Planck function describes the emission that occurs from materials with discrete energy levels, or energy bands, when its electron and hole population is driven out of chemical equilibrium with each other. Examples of such driving forces are the absorption of light in a solar cell or the e.m.f. applied to an LED. The fundamental conversion efficiency of solar cells can be calculated assuming that spontaneous re-emission of the absorbed solar radiation is the only loss mechanism. Tandem solar cell efficiencies as a function of top and bottom cell bandgap. This calculation is in the unconstrained limit of 4 terminal contacts (the cells are electrically isolated), and we also assume no photon recycling between the layers.