Analysis Of The Microscopic Mechanism Of The J-V Curve Of Organic Diode

As the scientific research value and economic benefits of organic light-emitting diodes are gradually increasing,the current-voltage relationship is a very important physical factor describing the electrical properties of organic light-emitting diodes,and it is obviously necessary to conduct in-depth research on it.Therefore,this article studies the current-voltage relationship of organic light-emitting diodes.The main content of this article is: Analyze the structural changes of organic light-emitting diodes and their lightemitting principles over the past decades.The organic light-emitting diode from its first appearance to the current mainstream structure is introduced,and the role of the functional layer in various structures is analyzed.The theoretical basis related to the current-voltage of organic light-emitting diodes is introduced,such as drift diffusion equation,drift current,diffusion current,Boltzmann statistics,Fermi statistics,Einstein relations,etc.Based on the drift diffusion equation,the OLED current-voltage formula is derived.In this work,a uniform electric field is used to approximate the electric field in the organic light emitting diode to obtain a numerical solution and the average carrier concentration is introduced to make the result more accurate.At present,many current-voltage work on organic light-emitting diodes does not consider the mobility model,but directly takes the mobility as a constant that is only related to temperature.This work adopts the mobility expression proposed by Pasveer et al.that considers temperature,electric field,and carrier concentration at the same time,and replaces the carrier concentration with the average concentration.The Boltzmann boundary condition is rewritten as the Fermi distribution boundary condition and the degeneracy coefficient is calculated.It is found that when Boltzmann statistics are used,Nv is usually regarded as a constant independent of temperature,but when Fermi is used statistics and considering non-degenerate,the analysis shows that Nv is related to temperature.The cathode and anode hole concentration equations calculated by Fermi statistics will include Nv,which avoids the limitations of using Boltzmann statistics.After the formula derivation is completed,use Matlab programming to realize it.Through the simulation of six organic light-emitting diode devices of different materials,the simulation images obtained are all qualitatively consistent with the experimental data and the effect is good,which verifies the accuracy and practicability of the model.The image output of the degeneracy coefficient,the relationship between the hole concentration and the length of the device,and the relationship between the average mobility and the length of the device are carried out,and the reasons are analyzed.Analyze the data points that the model does not fit well,and give the reasons for the prediction.The six parameters used in the model in this article,namely,band gap,anode barrier,cathode barrier,lattice constant,mobility constant,and Gaussian density of states width,are analyzed and predicted the impact of the simulation results..Overall,the simulation results of the model in this paper are in good agreement with the experimental data,which provides a good reference value for future research on the relationship between the current and voltage of organic diodes.