Simulation-assisted Exciton Binding Energy and Lowest Unoccupied Molecular Orbital Energy Determination using Field-induced dissociation

Consumer adoption of organic light-emitting diodes (OLEDs) is rising rapidly and the demand for highperformance OLEDs is increasing with it.To produce higher performance OLEDs, device structures and materials must improve.With an influx of research on new materials, a fundamental understanding of the frontier molecular orbital energies is required.Specifically, determining the energy of the lowest unoccupied molecular orbital (LUMO) is challenging.Most methods to determine the LUMO energy do not reach the accuracy required for device design, hindering applications.This thesis explores the simulation-assisted field-induced dissociation method as a means to more accurately extract LUMO energies.The thesis was split into three parts.Part one discussed a binary hole-based dissociation system of the sky-blue emitter FIrPic and the electron donor BCzPh.Part two introduced the inert host UGH-2 into the binary hole-based dissociation system presented in part one.Part three investigated multiple FIrPic and electron acceptor systems.The simulations presented in parts one and two described most experimental binary compositions reliably.Simulated compositions containing less than 10% FIrPic showed unphysical device charging and were deemed unreliable.A FIrPic exciton binding energy of 1.2 eV and a LUMO energy of -2.05 eV was determined from the simulations.In part three the LUMO energy differences between FIrPic and the electron acceptors mSiTrz, B4PymPm, 3P-T2T, and PO-T2T were determined to be ≤ 0.08 eV, ≈ 0.10 eV, ≈ 0.19 eV, and ≈ 0.23 eV, respectively.Comparison with exciplex-based estimates revealed significant deviations in the extracted LUMO energy differences.These deviations were, mainly, attributed to the large static dipole moment and relative dielectric constant of FIrPic, not considered in the exciplex estimates.