Magnetic Field Effects of Charge Transfer Excitons in Organic Semiconductor Devices

Abstract

AbstractThe topic of this review is the effect of magnetic field on photo‐current (PC) in organic semiconductor devices. Magnetic field modifies the fraction of the singlet/triplet population in the charge transfer excitons (CTE) whose lifetime is spin configuration dependent yielding magneto‐PC (MPC). We review MPC in the framework of the polaron pair model and emphasize the effect of CTE lifetime on MPC. In addition to a detailed calculation of the MPC response we find a range of physical parameters in which the response follows a simple ′fit function′. For example, a sum of wide and narrow Lorentzian functions, MPC(B)=cwB2/(B2+bw2)+cnB2/(B2+bn2), in the case of hyperfine interaction; or a Voigt profile V=L*G, where the sign * stands for the convolution operation between a Lorentzian (L) and a Gaussian (G) functions, in the case of thermal spin polarization. We provide expressions for the fit parameters in terms of physical parameters.