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Dahal, Ekraj

Materials Science Graduate Program

2022

Ph.D.

This thesis comprises a series of methods for controlling the electroluminescence from Fabry-Pérot microcavity OLEDs by varying the resonator geometry and the location of the organic emitter within the resonator. In pursuit of this thesis, I conducted three experimental projects backed by theoretical modeling. First the thickness of the microcavity was varied to observe changes in resonant state wavelength, linewidth of the states, angular dispersion, and polarization splitting. The resulting electroluminescence can be tuned to span the entire color gamut using a single green chromophore. Electroluminescence of this green chromophore was used to pump the optical states of nominally identical microcavity resonators by changing the position of the emitting organic molecule within the resonator. The efficiency of electroluminescence is seen to have a positional variance due to the emitting molecule position. Finally, an analogous experiment was designed using coupled Fabry-Pérot microcavity resonators. In a coupled resonator system, each of the photonic states splits into two states, one with slightly higher and other with slightly lower energy. Electrically pumping either the top, or the bottom produced relatively the same electroluminescence spectrum. We attribute this to the symmetry of the two-cavity system. Pumping both cavities together had a superposition effect on the electroluminescence spectrum. These contributions advance the knowledge of light matter interaction of organic semiconductors in photonic resonators with potential advantages for narrow band or broad-spectrum light emissions.