2.5 Generation

\(\mathtt{\require{color}{\color[rgb]{0.000000000000000,0.500000000000000,0.500000000000000} SimSS}}\) and \(\mathtt{\require{color}{\color[rgb]{0.000000000000000,0.500000000000000,0.500000000000000} ZimT}}\) equate the generation rate of free electrons and holes either to the generation rate of electron-hole pairs (parameter \(\mathtt{\require{color}{\color[rgb]{0.000000000000000,0.500000000000000,0.500000000000000} G\_ ehp}}\))–common in non-excitonic materials—or they consider that such electron-hole pairs may be subject to geminate recombination losses. [ 12 , 13 , 14 ] If such geminate losses are taken into account (\(\mathtt{\require{color}{\color[rgb]{0.000000000000000,0.500000000000000,0.500000000000000} fieldDepG}}\)=1), then the generation rate is reduced by a factor \(P(x)\), given by

\begin{equation} P(x) = \mathtt{\require{color}{\color[rgb]{0.000000000000000,0.500000000000000,0.500000000000000} P0}}~ + (1-\mathtt{\require{color}{\color[rgb]{0.000000000000000,0.500000000000000,0.500000000000000} P0}}~ )p(\mathtt{\require{color}{\color[rgb]{0.000000000000000,0.500000000000000,0.500000000000000} a}}~ ,T,F), \end{equation}

where \(p(a,T,F)\) is the Onsager-Braun dissociation probability, [ 14 ] \(\mathtt{\require{color}{\color[rgb]{0.000000000000000,0.500000000000000,0.500000000000000} a}}\) is the charge separation distance, and \(\mathtt{\require{color}{\color[rgb]{0.000000000000000,0.500000000000000,0.500000000000000} P0}}\) is the fraction of electron-hole pairs that directly yield free carriers. The dissociation probability \(p(a,T,F)\) can be integrated over a distribution of electron-hole pair distances, i.e.,

\begin{equation} P(a,T,F)=\int _0^\infty p(y,T,F)g(a,y)d y, \end{equation}

where \(g(a,y)\) is a normalized distribution function that can be specified by parameter \(\mathtt{\require{color}{\color[rgb]{0.000000000000000,0.500000000000000,0.500000000000000} thermLengDist}}\).