VIRTUAL

 Thursday, July 14th 2022

3:45 – 4:45 pm (MT)

WEBEX 

 Speaker:  Dr. Tracy H. Schloemer

Stanford University


“Harnessing Photons with Organic Semiconductors”
 
Abstract: 
Light has a bright future as a stimulus for chemical processes due to its abundance and accessibility. Engineering organic semiconductors to effectively harness photons within complex systems has been the primary theme of my research endeavors. In the first part of my talk, I will address the operational stability of perovskite solar cells (PSCs) via hole-transport layer (HTL) design. We find that triarylamine-based dopants must contain at least two para-electron-donating groups for maintaining excellent material properties, which allows for the ability to mix and match these dopants with a nonidentical small-molecule-based HTL matrix. This broadens the HTL design scope for highly stable PSCs. In the second part of my talk, I will discuss volumetric 3D printing and how we overcome obstacles typically encountered with two-photon absorption-based 3D printing, such as high power density requirements and slow print speeds. By encapsulating materials that can facilitate triplet fusion upconversion (UC) within a silica shell, we can induce photopolymerization deep within a vat of 3D printing resin at power densities multiple orders of magnitude lower than power densities required for two-photon-based printing. With simple structural tuning of the organic semiconductor emitter incorporated inside of the nanocapsule, we can systematically control the upconversion threshold which allows for either monovoxel or parallelized printing schemes. The ability to simply exchange the UC nanocapsule contents is a critical feature that enables discrete, localized photochemistry for many applications within the realm of 3D printing and beyond. Taken together, engineering tunable organic semiconductor platforms such as these will enable cross-cutting innovations across many fields.

Bio: Tracy H. Schloemer earned her B.S. in Chemistry in 2009 and M.A. in educational studies in 2010 from the University of Michigan, Ann Arbor. She taught high school chemistry in Denver, Colorado as a Knowles Teaching Initiative fellow for six years, and was so effective at persuading her students to pursue science, she accidently convinced herself to do the same. She earned her Ph.D. in applied chemistry from the Colorado School of Mines in 2019, where she focused on organic semiconductor design for improved operational durability of perovskite solar cells under Professor Alan Sellinger and in collaboration with the National Renewable Energy Lab. In 2019, she began her postdoctoral studies at the Rowland Institute at Harvard and then Stanford University under Professor Dan Congreve. Her current research focuses on the control and application of excitons.