Intramolecular charge transfer (ICT) happens when photoexcitation causes an electron to transfer from a donor to an acceptor within the same molecule, often stabilized by an orthogonal twist between them. This phenomenon is leveraged in thermally activated delayed fluorescence (TADF) to harness triplet excitons in OLEDs.
However, the twisted conformation in TADF molecules limits device lifetimes. While rigid molecules enhance stability, their planar, π-conjugated structures hinder ICT, making it challenging to improve performance.
Scientists from the top-rated Physics department and Newcastle University have developed an innovative method to enhance the stability and efficiency of organic light-emitting diodes (OLEDs). This breakthrough involves the use of a unique type of molecule, which holds the potential to extend the lifespan of OLED devices significantly.
The researchers have developed a novel approach to designing organic molecules that retain stability and efficiency over time, even under high-stress conditions. These new molecules challenge existing concepts of intramolecular charge transfer excited states, proposing a groundbreaking model that links molecular bonding patterns to breaking pi-conjugation in the excited state and explaining this new phenomenon.
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These molecules, known as “rigidly planar charge-transfer molecules,” improve triplet harvesting, which enhances OLED efficiency through thermally activated delayed fluorescence (TADF). Unlike traditional OLED molecules, which often twist and lose stability, the new design maintains a stable structure, ensuring longer-lasting device performance.
The new approach could make OLED devices more durable, reducing the need for frequent replacements.
Journal Reference:
- Kuila, S., Miranda-Salinas, H., Eng, J. et al. Rigid and planar π-conjugated molecules lead to long-lived intramolecular charge-transfer states exhibiting thermally activated delayed fluorescence. Nat Commun 15, 9611 (2024). DOI: 10.1038/s41467-024-53740-1
