No abstract

This study demonstrates an analytical relation that models the carrier injection in metal-organic interfaces and which considers two consecutive carriers hopping as the injection mechanism. The new formula has superior attributes and can surpass conventional relations, in particular the thermionic emission-diffusion formula. For example, the model can properly trace the temperature dependency of the injection up to temperatures as low as 30 K and the full range of electric fields. Also, the prominence of joule heating for proper modeling of the injection is presented. This study examines the validity of the introduced analytical equation by exploring the injection in several practical contacts extracted from the literature, the results of which are discussed in this paper.

Several methods to simulate the behavior of organic light-emitting diodes (OLEDs) have been proposed in the past. In this paper, we develop a previous method, based on the master equation, in order to allow the simulation of time-dependent behavior and transient states. The calculation algorithm of the program that we have written is described. The time-dependent behaviors of two simple monolayer devices and of a more complicated three-layer device were simulated by means of this program, and the results are discussed. The results show that the turn-off speed of an OLED might be very slow, especially in the case of a multilayer device. This behavior is related to the low mobility of the organic material in weak electric fields. An interesting feature of the time behavior is pointed out, whereby the recombination rate may become considerably larger after the falling edge of an applied voltage pulse. Moreover, the validity of the transient electro-luminescent method for measuring carrier mobility in organic material has been examined by means of simulation. The results show that there is some inconsistency especially in high electric fields.