Space organic semiconductors

Researchers have used various models to explain the charge carrier transport mechanism in organic semiconductors. Two models have been used frequently, (i) the trapping model, which assumes a certain distribution of traps in the energy space and (ii) the field dependent mobility model, which assumes an exponential dependence of mobility on square root of electric field. 

Charge Transport in Disordered Organic Semiconductors 297 8.6.5.2 The Theory of Space-Charge Limited Currents in Disordered Films... 

Since the polymer can be synthesized to such a high purity, a more appropriate description for the space charge is that given by trapped charges, rather than ionized impurities. Traps may arise, e.g., from conformational defects of the organic semiconductors. It is then the density of the traps in the polymer... 

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