Magnetoresistance in organic semiconductors: including pair correlations in the kinetic equations for hopping transport

Abstract

We derive the kinetic equations for polaron hopping in organics that explicitly take into account the double occupation possibility and pair intersite correlations. The equations include simplified phenomenological spin dynamics and provide a self-consistent framework for the description of the bipolaron mechanism of the organic magnetoresistance. At low applied voltages the equations can be reduced to effective resistor network that generalizes the Miller-Abrahams network and includes the effect of spin relaxation on the system resistivity. Our theory discloses the close relationship between the organic magnetoresistance and the intersite correlations. Moreover, in the absence of correlations, as in ordered system with zero Hubbard energy, the magnetoresistance vanishes.

17 pages 10 figures accepted for publication in Physical Review B

References in corpus (3)

• The effects of spin-spin interactions on magnetoresistance in disordered organic semiconductors
• Hyperfine-induced spin relaxation of a diffusively moving carrier in low dimensions: implications for spin transport in organic semiconductors
• Memory effects, two color percolation, and the temperature dependence of Mott's variable range hopping

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• Microscopic theory of OMAR based on kinetic equations for quantum spin correlations
• The system of correlation kinetic equations and the generalized equivalent circuit for hopping transport
• Electric current noise in mesoscopic organic semiconductors
• Dynamic spin polarization in organic semiconductors with intermolecular exchange interaction