Electric Field-Assisted Dissociation of Excited States

ELECTRIC FIELD-ASSISTED DISSOCIATION OF EXCITED STATES 

The PF formalism treats the electron-hole pair dissociation as a one step carrier escapes from the Coulomb field of the countercharge due to external field-assisted thermal activation over the barrier. The two steps in the formation of a free carrier pair, as shown in Fig. 48, are undistinguishable. In other models of the exciton dissociation process, these two steps are separable, and the overall quantum efficiency expressed by the product 

It is often assumed that the rate constant for carrier production is characterized by an exponential function [310,311] 

The probability of the dissociation of the CT state into a pair of separated carriers, and its functional form is determined by the mechanism of final charge separation [Q(F)]. Besides the one-step PF dissociation process (130), the Onsager formalism is often used to describe l(F) [314,315] 

The field dependence of Q0ns(F) appears in a complex manner through the parameter B which determines the expansion terms of the infinite series in Eq. (138). The expansion coefficients in Eq. (138) are governed by the so-called Onsager radius at which the Coulombian attraction is equal to the thermal energy, kT 

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