NOTES ON STATISTICAL PRINCIPLES

The solar cell equation is derived (Section 2) in terms of transition probabilities and this leads to a consideration of the principle of de tailed balance, and also of the extent to which it is justifiable to a ssume that the transition probabilities involved are excitation-indepe ndent. A fuller discussion, with some applications, is then given of d etailed balance (Section 3). If it cannot be applied, it may still be justifiable to adopt the weaker steady-state assumption, backed up by the hypothesis of quasi-Fermi levels. This can lead (Section 4) to pho ton distributions with a non-zero chemical potential (which is imposed on the photons by the fermions). A more general discussion of some st atistical mechanical principles is also given (Section 5).