The Seebeck Coefficient for Disordered Organic Semiconductors

The Seebeck coefficient is used to describe the transport of carriers and sensitive to the shape of density of state. However, the density of state in organic semiconductors is unclear at present. Some researches incline to apply the Gaussian or exponential density of state. In this paper, we propose an exponential-type density of state with clearly cutting tail at same place. Based on the Miller-Abrahams hopping model, we calculate the variation of initial energy and escape energy for different temperature, analysis the dependence of the conductivity to Seebeck coefficient, and compare the influence of $\lambda$ and energetic disorder to the Seebeck coefficient in different temperature by exponential-type DOS (EC DOS) cutting tails at some place.