Undergraduate Thesis Or Project


A Study of Charging Behaviors in Organic Semiconductors using Optical Trapping Public Deposited

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  • We measure the charging and discharging of two organic materials, PCBM and ADT-TES-F. These materials are studied through the noncontact method of particle trapping known as Optical Tweezers, where an IR laser is used to constrain the motion of a coated or noncoated silica sphere while its positional data is recorded. The surface charge of the sphere is calculated via an induced driving electric field. We focus on the governing experimental parameters of the electric field frequency, electric field intensity, and the power of a PL inducing excitation laser. These parameters directly affect the surface charge density of a silica sphere trapped in an optical tweezer by altering the environment in which surface charge is induced. These parameters also govern how charges move in the valence and conduction bands. In previous research the electric field frequency and amplitude were set to values that did not yield a reliable surface charge. The electric field applied to the coated or noncoated spheres must exhibit a driving frequency greater than 300 Hz in contrast to the previously used 100-110 Hz. The electric field amplitude must be greater than 2000 V/m to produce reliable surface charge measurement in contrast to the previously used 500-1000 V/m field. The power of that excitation laser has no effect on the surface charge density of plain silica spheres regardless of the presence of PCBM. Knowing the required parameters removes the need to have a calibration factor applied to future experiments conducted with spheres coated with the photo luminescent ADT-TES-F.
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  • Funded by OSU URISC
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