Simulation of the performance of organic electronic devices based on a two-dimensional drift-diffusion approach

Organic electronic devices will play an important role in future technical applications because of their easy production and low costs. Besides intrinsic material properties, the performance of organic solar cells, light emitting diods and thin-film transistors depends strongly on the morphology, the occurring hetero-junctions, as well as on achieving an appropriate alignment of transport levels. To optimize the efficiency of organic devices it is, therefore, important to understand what limits their performance. The paper supports this concern by providing a general model for simulating the exciton and charge carrier transport in such building blocks. Due to the complex internal structure and the large aspect ratios of the active device regions, the procedure is based on drift-diffusion equa- tions. All of the necessary source, generation and recombination terms are included in the developed model. The applied numerics is based on finite difference approaches and especially on the Scharfetter-Gummel algorithm. Three examples, which prove the appli- cability of the established formalism to enhance the performance of organic devices are given. The performed simulations reveal interesting particularities of the carrier transport in these devices.