Rachel Aga (Advisor), David Dolson (Committee Member), Emily Heckman (Committee Member), Ioana Sizemore (Committee Member)
Master of Science (MS)
Work function tunability of metal electrodes provides a route to improving performance of organic electronic devices. Using an electrode with a different work function changes the potential barrier at the polymer/electrode interface, leading to altered device characteristics, such as turn-on voltage in light emitting diodes or series resistance photodiodes. In this work, we explore work function modification by employing solution-based conducting materials, poly(3,4-ethylenedioxythiophene) : poly(styrene sulfonate) (PEDOT:PSS) and carbon nanotubes (CNTs), printed as overcoatings on oxidized Ni. The capability of direct write technologies, namely inkjet and aerosol jet printing, to control thin film thickness is investigated. The correlation between film thickness and work function is evaluated from profilometer measurements and ambient Kelvin probe measurements of the work function of the modified electrode. We find that aerosol jet printing is an attractive tool for modifying printed film thickness of PEDOT:PSS and CNTs. The achieved variation in thickness of printed films allows for work function modification exhibiting values that vary from the bare oxidized Ni value to the bulk PEDOT:PSS or CNT value as the thickness of the printed film is increased. Further, we fabricate infrared Schottky photodetectors, with poly(3-hexylthiophene):C61-butyric acid methyl ester (P3HT:PCBM) composite as the active organic layer, to demonstrate the change in device performance with the implementation of the PEDOT:PSS- and CNT-modified electrodes. The test devices exhibited improvement in photodetection with implementation of the modified electrodes.
Department or Program
Department of Chemistry
Year Degree Awarded
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