Heavy-Atom-Free Bay-Substituted Perylene Diimide Donor-Acceptor Photosensitizers |
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Authors: | Jasper Deckers Dr Tom Cardeynaels Dr Laurence Lutsen Prof Benoît Champagne Prof Wouter Maes |
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Institution: | 1. UHasselt-Hasselt University, Institute for Materials Research (IMO), Design & Synthesis of Organic Semiconductors (DSOS), Agoralaan, 3590 Diepenbeek, Belgium;2. IMEC, Associated Lab IMOMEC, Wetenschapspark 1, 3590 Diepenbeek, Belgium;3. UNamur-University of Namur, Laboratory of Theoretical Chemistry (LTC), Theoretical and Structural Physical Chemistry Unit, Namur Institute of Structured Matter, Rue de Bruxelles 61, 5000 Namur, Belgium |
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Abstract: | Perylene diimide (PDI) dyes are extensively investigated because of their favorable photophysical characteristics for a wide range of organic material applications. Fine-tuning of the optoelectronic properties is readily achieved by functionalization of the electron-deficient PDI scaffold. Here, we present four new donor-acceptor type dyads, wherein the electron donor units – benzo1,2-b : 4,5-b’]dithiophene, 9,9-dimethyl-9,10-dihydroacridine, dithieno3,2-b : 2’,3’-d]pyrrole, and triphenylamine-are attached to the bay-positions of the PDI acceptor. Intersystem crossing occurs for these systems upon photoexcitation, without the aid of heavy atoms, resulting in singlet oxygen quantum yields up to 80 % in toluene solution. Furthermore, this feature is retained when the system is directly irradiated with energy corresponding to the intramolecular charge-transfer absorption band (at 639 nm). Geometrical optimization and (time-dependent) density functional theory calculations afford more insights into the requirements for intersystem crossing such as spin-orbit coupling, dihedral angles, the involvement of charge-transfer states, and energy level alignment. |
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Keywords: | charge transfer intersystem crossing perylene diimides photosensitizers singlet oxygen |
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