Estimation of van der Waals component of the density of states using the Gaussian disorder model and the correlated disorder model

摘要

Abstract: The proportionality of the logarithm of the mobility to the square root of the electric field is most likely caused by the broadening of the density of states according to both the Gaussian disorder model and the 3D correlated disorder model (CDM). Using these models, the relation between the slope of the mobility against the electric field and the dipolar component of the width of the density of states ($sigma$-d$/) is analyzed. The $sigma$-d$/ for the donor and the host polymer are calculated using the dipolar disorder model in which a random distribution of permanent dipoles generates fluctuation in electric potential. A successful interpretation of the relation between $beta and $sigma$-d$/ has been achieved using the formula based on the CDM. Assuming that all components of the density of states are described using Gaussian statistics, the van der Waals component is evaluated to be negligibly small from analyses of temperature dependence of the relation between $beta and $sigma$-d$/. The experimental results also shows that the value of the DOS width that is derived from the analysis of the temperature dependence of the zero-field mobility is different for the value of the DOS width that is derived from the analysis of the electric field dependence. !16