Modulation of delayed fluorescence pathways via rational molecular engineering

Schematic representation of various photophysical processes (Image courtesy: Sanchari Debnath)

Organic light-emitting diodes (OLEDs) have attracted immense attention in display and illumination technologies due to their flexible device structures and multicolour emission. However, one of the key challenges in developing efficient OLEDs is overcoming the loss channel of triplet excitons. Triplet excitons are long-lived with very low radiative efficiencies and are primarily unutilised, which limits the overall efficiency of OLEDs.

Over the years, OLED research has sought ways to overcome the inherent limitation imposed by charge recombination spin statistics. A widely adopted method to reduce these losses and boost external quantum efficiency involves the use of emitter molecules designed for thermally activated delayed fluorescence (TADF) or triplet-triplet annihilation (TTA). Nevertheless, achieving both in the solid state from the same organic chromophore poses a formidable challenge due to the energetic and structural requirements that need to be met simultaneously.

In a recent study published in Nature Communications, researchers from the Solid State and Structural Chemistry Unit (SSCU), led by Satish Patil and PhD student Sanchari Debnath, have introduced a donor-acceptor chromophore design that enables both thermally activated delayed fluorescence (TADF) and triplet-triplet annihilation (TTA) in thin films of organic semiconductors.

This work serves as a proof-of-concept, showing how different emission mechanisms can be harnessed from a single donor-acceptor system through strategic donor selection. The present design has the potential to be adapted to a wide range of delayed fluorescence emitters through molecular engineering, opening up new possibilities for their exploration in OLED applications.

Sanchari Debnath                                                                       Satish Patil
(PhD student, Lead author)                                                     (PI, Corresponding author)

REFERENCE:
Debnath S, Ramkissoon P, Salzner U, Hall CR, Panjwani NA, Kim W, Smith TA, Patil S, Modulation of delayed fluorescence pathways via rational molecular engineering, Nature Communications (2025)
https://www.nature.com/articles/s41467-025-56987-4

LAB WEBSITE:
https://oe-sscu.iisc.ac.in/prof-satish-patil/