ABSTRACT
The charge recombination process can be defined as a fusion of a positive (e.g. hole) and a negative (e.g. electron) charge carrier into an electrically neutral entity though the positive and negative charge centers on it do not necessarily coincide. The radiative decay of such an entity or following its evolution successive excited states produces light called recombination radiation. This underlies directly recombination EL, the EL type depicted in Fig. 1c,d to be compared with other types of EL phenomena (Figs. 1a, b) in which the recombination radiation still can participate as mentioned in Preface. The initial (or geminate) recombination and volume-controlled recombination can be distinguished on the basis of charge carrier origin.
