Studies On Improving The Performance Of Fluorescent Organic Electroluminescent Device

There is still a long way for organic electroluminescent industrialization to go as the existence of problems such as internal mechanism is not clear, efficiency of the device is low and so on. According to the above problem, the studies of the PCDTBT application in OLED being used as emitting layer and the numerical simulation upon single layer MEH-PPV device with a software named SETFOS have been done in the thesis:Firstly, the narrow gap material PCDTBT has been used in electroluminescent device as emitting layer for the first time in the thesis and shows excellent performance with the EL spectrum of705nm, furtherly, the effect of annealing on PCDTBT layer upon the performance of the device has been studied. The results suggest that, the color coordinates is (0.72,0.28). after optimizing, the device shows better performace with turn-on voltage of2V, the highest brightness25000cd/m2, the maximum current efficiency at3.5cd/A. It is demonstrated that PCDTBT may be a promising non-doped red material for PLED. Furtherly, study on PCDTBT annealing with different temperature upon the performace of the device has been done. The results suggest that the annealing has few effects with the EL spectrum of the device but influences the current, brightness and efficiency. With annealing temperature increasing, the performance of the device has been firstly impoved and then reduced, which is because the low temperature annealing is beneficial to the solvent volatilizing, which improving the film; The higher temperature annealing PCDTBT helps to reduce the length of π-π stacking, which resulting in decreasing the mobility in PCDTBT, thereby leting the performance down.Secondly, simulating the single layer MEH-PPV devices with the software SETFOS3.3, not only the I-V curve, L-V curve and the EL spectrum of the device but also the relation between the distribution of the inside electric potential, electric field strength, the electron current, hole current, the electron mobility, the hole mobility with the location of emitting layer is obtained. Simulation upon the thickness of MEH-PPV layer has also been done, the results reads that thickness plays a essential role in OLED device. Thickness affects not only the transmission and the balance of the carriers, but also the total resistance of the device, which affects the current density of the device.