Brian Johnson (Ostroverkhova group) has received the 2015 Physics Graduate Research Award in recognition of his work on organic semiconductors.
He describes his work as follows.
I have focused on studying the charge photogeneration, carrier transport, and carrier trapping mechanisms in small molecule organic semiconductor materials, specifically, functionalized derivatives of pentacene and anthradithiophene. I developed a computational model which simulates experimental data and fits those simulations to measured data to extract quantitative material parameters. My work helps to answer one of the most important open questions in organic semiconductor material physics: what, exactly, is the process by which charge photogeneration happens? Classic models have been shown to be incomplete, and my work fits into gaps in the current research towards this topic, as much more work has been done on polymers than in small molecules, and investigations of nanosecond time scale carrier dynamics are rare. This work is important to the development of new materials for organic LEDs, solar cells, and transistors.
Lee Aspitarte is a fourth year PhD student working with Prof. Ethan Minot, and recipient of this year’s Ben and Elaine Whiteley Materials Research Fellowship. He is studying photocurrent generation in photodiodes fabricated from single carbon nanotubes (CNTs). CNTs are exciting candidates for next generation solar technology because they undergo Multiple Electron-hole pair Generation (MEG), where carriers excited by a photon with an energy of more than twice the band gap can decay by exciting additional electron-hole pairs. By utilizing MEG, CNT based solar technology could exceed the theoretical limit on solar power conversion efficiency for silicon based technology, 29%. The research funded by this fellowship will study MEG in CNT photodiodes by manipulating the dielectric environment surrounding the CNT, affecting the electron-electron scattering processes that lead to MEG. The knowledge gained from this study could directly impact design considerations for next-generation high-efficiency MEG based solar cells. Mr. Aspitarte received the Peter Fontana Outstanding Graduate Teaching Assistant Award in 2012 and has already co-authored two papers on his research at Oregon State.
The Ben and Elaine Whiteley Endowment for Materials Research, established in 2007, provides support for materials research in the College of Science. In particular, it provides fellowship support for students to work full time during the Summer in a research laboratory, working on materials research related topics.