Enhanced Photostability through Rapid Exciton Decay in Desymmetrized Cyclopentannulated Acenes with Strong Face-to-Face pi Stacking

Authors

• Chad D. Cruz, National Institute of Standards and TechnologyFollow
• Karl J. Thorley, University of KentuckyFollow
• Zachary J. Knepp, Lehigh University
• Jared Wahlstrand, National Institute of Standards and Technology
• Gil M. Repa, Lehigh University
• John C. Stephenson, National Institute of Standards and Technology
• Sean Parkin, University of KentuckyFollow
• Lisa A. Fredin, Lehigh University
• John E. Anthony, University of KentuckyFollow
• Emily G. Bittle, National Institute of Standards and TechnologyFollow

Abstract

The photophysics of organic semiconductors impacts their efficiency in optoelectronic devices where exciton transitions, including singlet fission, intersystem crossing and the formation of charge transfer states influence the ability to convert between bright and dark states and to dissociate into free charges. Unfortunately, photodegradation and spurious signals often confound the results of optical studies, especially of important triplet states. Here four asymmetric cyclopentannulated acenes are synthesized and studied. This system represents an extreme in photophysics achieved via molecular design to fully quench the photoluminescence and bypass triplet formation allowing for comparative studies with other highly absorbing acenes. Rapid molecular exciton decay that is unaffected by strong electronic coupling induced by the crystal packing is found. The quick return to the ground state inhibits the formation of triplets and leads to heating in the solid state. These aceacenes are photostable both in solution and as single crystals, likely because the short excited-state lifetime diminishes the chances for deleterious photoreactions. Density functional theory calculations highlight excited state twisting in the five-membered ring, indicating a key driver of rapid internal conversion.

Document Type

Article

Publication Date

2026

Notes/Citation Information

© 2026 The Authors. Published by American Chemical Society

Digital Object Identifier (DOI)

https://doi.org/10.1021/acs.chemmater.5c02815

Funding Information

C.D.C., J.W., and E.G.B. acknowledge support from the National Institute of Standards and Technology Physical Measurement Laboratory. LAF acknowledges support from a 2024 Sloan Research Fellowship from the Alfred P. Sloan Foundation. L.A.F. and Z.K. acknowledge support from the National Science Foundation under Grant No. CHE-2310205. Research computing resources were provided by Lehigh University partially supported by the NSF CC* Compute program through Grant No. OAC-2019035. This work used Bridges2 at Pittsburgh Supercomputing Center through allocation TG-CHE190011 from the Advanced Cyberinfrastructure Coordination Ecosystem: Services & Support (ACCESS) program, which is supported by National Science Foundation grants #2138259, #2138286, #2138307, #2137603, and #2138296. GMR acknowledges support from Lehigh University. KJT and JEA acknowledge support from the National Science Foundation under grant no. DMR-232422.

Repository Citation

Cruz, Chad D.; Thorley, Karl J.; Knepp, Zachary J.; Wahlstrand, Jared; Repa, Gil M.; Stephenson, John C.; Parkin, Sean; Fredin, Lisa A.; Anthony, John E.; and Bittle, Emily G., "Enhanced Photostability through Rapid Exciton Decay in Desymmetrized Cyclopentannulated Acenes with Strong Face-to-Face pi Stacking" (2026). Chemistry Faculty Publications. 209.
https://uknowledge.uky.edu/chemistry_facpub/209