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Measurement of Charge-Density Dependence of Carrier Mobility in an Organic Semiconductor Blend



Here, a new methodology for analyzing the charge-density dependence of carrier mobility in organic semiconductors, applicable to the low-charge-density regime (1014–1017 cm−3) corresponding to the operation conditions of many organic optoelectronic devices, is reported. For the P3HT/PCBM blend photovoltaic devices studied herein, the hole mobility µ is found to depend on charge density n according to a power law µ(n)nδ, where δ = 0.35. This dependence is shown to be consistent with an energetic disorder model based upon an exponential tail of localized intra-band states.