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The Driving Force Controls Charge Separation Distance in Solid-State Organic Donor/Acceptors

Conference ·
DOI:https://doi.org/10.1117/12.3028219· OSTI ID:2447926
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.
Research Organization:
National Renewable Energy Laboratory (NREL), Golden, CO (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division
DOE Contract Number:
AC36-08GO28308;
OSTI ID:
2447926
Report Number(s):
NREL/PO-5900-91029; MainId:92807; UUID:07e21b25-3d58-4d25-b551-9ee71746dbb6; MainAdminId:73788
Conference Information:
Presented at the SPIE Optics + Photonics Exhibition, 20-22 August 2024, San Diego, California
Country of Publication:
United States
Language:
English