Study of the Hole and Electron Transport in Amorphous 9,10-Di-(2′-naphthyl)anthracene: The First-Principles Approach

An accurate description of charge transport in amorphous organic semiconductors is challenging. Many previously reported methods largely involve empirical parameters, which may hinder the understanding of the charge transport process in a specific material. In this paper, Born-Oppenheimer molecular dynamics (BOMD) is used to simulate the amorphous structure of a widely used small molecule 9,10-di-(2'-naphthyl)anthracene (ADN). Its hole and electron mobilities are calculated using an ab initio method. It is found that the inaccuracy in the calculation of the nonadiabatic couplings caused by the periodicity of the cell in the BOMD simulation can be greatly reduced by taking into account the mirror states in the surrounding cells. The calculated hole and electron mobilities both have the same order of magnitude with their corresponding experimental results, demonstrating the possibility to obtain reasonable charge transport mobilities for amorphous small-molecule semiconductors via the first-principles approach. Our work may shed light on the understanding of the charge transport process in amorphous organic semiconductors and the design of new charge transport materials.