Abstract
In this thesis, I mainly use the cyclic voltammetry (CV) and UV-Visible spectrum to measure the optical properties of polymer light emitting diodes (PLEDs) to compare with the quantum simulation results which are based on time-independent and time-dependent density functional theories (TI-DFT & TD-DFT) for microscopic analysis. PLEDs play an important role in organic electroluminescent (OEL) especially the emitting layer in PLEDs. One of the basic materials to fabricate the emitting layer is the polythiophene (PT). Therefore, it is important to exploit the material properties by experiments and appropriate simulations. In the quantum simulation part, since Gaussian function is not capable of representing periodically molecular structure, the first step is to set up T1(monomer), T2(dimer), T3(trimer), until T20 molecular models and then use the regression analysis to predict the band gap of the polythiophene. The absorption energies are then evaluated from the DFT and TD-DFT simulations. In the experimental part, using the cyclic voltammetry by varying the input potential is able to analyze the redox system of the emitting materials and to estimate their band gaps from the V-I plots. The oxidation potential (Eox) and the reduction potential (Ered) can be obtained, and are transformed to the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) accordingly. Finally, through experimental result verifications, this quantum simulation technique is concluded to be reliable and accurate for predicting the optical properties of modern PLEDs.