Numerical study of annihilation processes in electrically pumped organic semiconductor laser diodes

摘要

We examine the influence of various annihilation processes on the laser threshold current density of organic semiconductor laser diode structures. A three-layer laser diode structure is systematically investigated by means of numerical simulations. Our self consistent model treats the dynamics of electrons, holes and singlet as well as triplet excitons in the framework of a drift-diffusion model. The resulting particle distributions enter into the optical model. In our approach, we consider the actual waveguide structure and solve the resulting laser rate equation. The various annihilation processes are included as reactions between the different species in the device. We systematically vary the device dimensions and parameters of our singlet exciton annihilation model to identify the dominating quenching process in order to deduce design rules for potential organic laser diode structures. A standard material with typical material properties and annihilation rate coefficients is investigated. Singlet exciton quenching by polarons is identified as the main loss channel. The laser threshold in three layer devices is found to be very sensitive to the thickness of the emission layer.