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MolES Seminar: Dr. Tina Ng (UCSD)
MolES Seminar: Dr. Tina Ng (UCSD)
WhenTuesday, Nov 26, 2019, 1 – 2 p.m.
Campus locationMolecular Engineering (MOL)
Campus roomNanoES 181
Event typesLectures/Seminars
Event sponsorsMolecular Engineering and Sciences

Molecular Engineering and Sciences Seminar Series
Emerging Designs for Polymer-Based Optoelectronics
Abstract:  The shortwave infrared spectral region (SWIR: 1-3 m) is particularly powerful for health monitoring and medical diagnostics, because biological tissues show low absorbance and minimal SWIR auto-fluorescence, enabling greater penetration depth and improved resolution in comparison to visible light. However, conventional SWIR sensors are limited by complex die transfer and bonding processing. Here we are advancing SWIR photodiodes by using a new generation of semiconducting polymers that are processed by solution processing techniques and allow simple direct deposition. The bulk heterojunction photodiodes show photo-response spanning from the visible to 1.7 micron. We develop a physical model to pinpoint the origins of efficiency losses by decoupling the exciton dissociation efficiency and charge collection efficiency, and identify avenues that will improve sensor detectivity. Several demonstrations will show the various potential applications of organic SWIR photodiodes including blood pulse measurements, spectroscopic identification, and image reconstruction.

In addition, the same infrared polymers present opportunities to create energy dense supercapacitors. Here we present promising n-type polymers that retained 90% of initial capacitance after 5000 charge-discharge cycles. Through current-voltage and spectroscopic measurements, we infer the mechanisms that lead to capacitance fade and suggests structural and electrochemical strategies to realize high-endurance energy storage devices for flexible printed systems.
This weekly seminar brings together students, faculty and invited guests from various disciplines across campus to explore current trends in molecular engineering and nanotechnology. It is a forum for active interdisciplinary discussions. These talks are open to the public and attract a diverse audience of students and faculty.
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