Modelling of hole transport in a small-molecule organic material assuming carrier heating in a Gaussian density of states

摘要

A modelling approach for carrier transport in a Gaussin density of states is presented which takes into account that theenergetic distribution of carriers moving via Miller-Abrahams rates is affected by an electric field. This reorganisation ofthe energetic carrier distribution can be described by virtual carrier heating to an effective temperature. We show thatcombining this approach with an existing percolation model reproduces the field dependence found in computer studiesin literature for uncorrelated Gaussian disorder. Comparing to our experimental results, we also demonstrate that theparameterizations from these publications do not hold at low temperatures.We produced samples of 4,4′,4″-tris-(2-methylphenyl phenylamino)triphenylamine (m-MTDATA) doped into N,N'-diphenyl-N,N'-bis(1-naphthylphenyl)-1,1'-biphenyl-4,4'-diamine (NPB) in the ratio 1:1 with four different thicknessesfrom 50 nm to 400 nm and measured the IV curves in a temperature range from T=77 K to 346 K. We successfullydemonstrate a unified simulation of the samples’ IV characteristics over the entire temperature range under theassumption of carrier heating, which is not possible with published models for correlated and uncorrelated Gaussiandisorder.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.