Presentation Title

Optimization of Microcavity Organic Light Emitting Diodes with Varying Dipole Position

Abstract

Microcavity organic light emitting diodes (OLED) allow for significant narrowing of the emission bandwidth by employing two planar metallic electrodes encasing layers of organic films. We use Tris(8-hydroxyquinolinato)aluminum, Alq3, as the emissive layer (EML) with the electron transport layers (ETL) and hole transport layers (HTL) added in between the metal electrodes. The electrons and holes injected through the electrodes, when recombine in the emission layer give off light by emitting photons. Only certain specific wavelength of light resonates, while others destructively interfere and are eliminated due to microcavity effect. This effect suppresses the broadband electroluminescence of Alq3, producing narrow-band, angle- and polarization-dependent emission peaks where the emission intensity depends on both the transmissivity of the structure and the free-space emission intensity at the resonant wavelength. The resonant wavelength depends on the optical pathlength of device. The study on the microcavity OLED demands the understanding of this behavior of multi layers film. We vary the dipole position in a range of devices by adjusting the ETL and HTL layers at constant device thickness. We find a change in the optical pathlength due to the difference in index of refraction between the ETL and HTL layers and study their diode behavior.

Primary Faculty Mentor Name

Matthew S. White

Status

Graduate

Student College

Graduate College

Program/Major

Materials Science

Primary Research Category

Engineering & Physical Sciences

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Optimization of Microcavity Organic Light Emitting Diodes with Varying Dipole Position

Microcavity organic light emitting diodes (OLED) allow for significant narrowing of the emission bandwidth by employing two planar metallic electrodes encasing layers of organic films. We use Tris(8-hydroxyquinolinato)aluminum, Alq3, as the emissive layer (EML) with the electron transport layers (ETL) and hole transport layers (HTL) added in between the metal electrodes. The electrons and holes injected through the electrodes, when recombine in the emission layer give off light by emitting photons. Only certain specific wavelength of light resonates, while others destructively interfere and are eliminated due to microcavity effect. This effect suppresses the broadband electroluminescence of Alq3, producing narrow-band, angle- and polarization-dependent emission peaks where the emission intensity depends on both the transmissivity of the structure and the free-space emission intensity at the resonant wavelength. The resonant wavelength depends on the optical pathlength of device. The study on the microcavity OLED demands the understanding of this behavior of multi layers film. We vary the dipole position in a range of devices by adjusting the ETL and HTL layers at constant device thickness. We find a change in the optical pathlength due to the difference in index of refraction between the ETL and HTL layers and study their diode behavior.