Paper 13127-45
Driving Force Controls Charge Separation Distance in Solid State Organic Donor/Acceptors
19 August 2024 • 5:30 PM - 7:00 PM PDT | Conv. Ctr. Exhibit Hall A
Abstract
In this work, charge pairs of varying separation distance are interpreted from photoinduced absorption detected magnetic resonance (PADMR) spectroscopy of organic, small molecule dilute donor/acceptor thin films. We report that a donor/acceptor film that generates few free charges at room temperature yet has a relatively large, calculated driving force for electron transfer generates a large concentration of tightly bound CT states when measured with PADMR. These states are markedly absent in films with smaller driving forces yet higher free charge yields which instead only show charge-separated state signals with weaker spin coupling. We interpret this result to be in support of a hypothesis where a larger reorganization energy associated with charge transfer to tightly bound CT states means that they are primarily generated in systems far from the Marcus optimum for free charge yield. And the highest free charge yielding systems instead predominantly undergo long-range charge separation into the acceptor host.
Presenter
Leo Romanetz
Univ. of Colorado Boulder (United States)
Leo is a third year PhD student at the University of Colorado Boulder. Under the advisement of Dr. Obadiah Reid and Dr. Garry Rumbles, Leo conducts his research at the National Renewable Energy Lab in Golden, Colorado where his group focuses on studying fundamental charge transfer dynamics in organic semiconductor materials. Leo's research interests are in using various optically-detected, time-resolved and electron paramagnetic resonance techniques to study these systems and in particular, better elucidate the role of charge transfer states as they relate to charge-separation mechanisms in organic photovoltaic devices.