Student Seminar
Name: Ms. Kavya
Title: Near-Infrared Emitters and their Applications
Date & Time: Thursday, 11th September 2025 at 4.00 p.m.
Venue: Rajarshi Bhattacharyya Memorial Lecture Hall, Chemical Sciences Building
Abstract:
Near-infrared (NIR) emitters is a growing field of research due to their widespread applications in optoelectronics1, energy, and biomedical field2, yet their performance is fundamentally limited by non-radiative decay predicted by the energy gap law3,4. High frequency vibrational modes in π-conjugated frameworks typically accelerate these losses, leading to reduced photoluminescence quantum yields (PLQEs). Recently some studies have shown that radical based doublet emitters5 and D-A based thermally activated delayed fluorescence (TADF) systems can suppress such vibrational coupling. In radicals, the open-shell doublet manifold allows spin-allowed emission from HDMO→SOMO charge-transfer excitons, enabling near-unity internal quantum efficiency. Molecular design strategies like orbital engineering (regioselective donor placement, disjoint frontier orbitals) and host-guest interactions (rigid, dielectric hosts that stabilize charge transfer and restrict vibrational motion) can further minimize vibrational losses. In this seminar, I will discuss the grand challenges to achieve high quantum efficiency in NIR dyes and their applications in optoelectronics devices and biology.
References:
(1) Xu, M.; Li, X.; Liu, S.; Zhang, L.; Xie, W. Near-Infrared Organic Light-Emitting Materials, Devices and Applications. Mater. Chem. Front. 2023, 7 (20), 4744–4767.
(2) Chen, L.; Chen, M.; Zhou, Y.; Ye, C.; Liu, R. NIR Photosensitizer for Two-Photon Fluorescent Imaging and Photodynamic Therapy of Tumor. Front. Chem. 2021, 9 (February), 1–8.
(3) Liu, Q.; Vandewal, K. Understanding and Suppressing Non-Radiative Recombination Losses in Non-Fullerene Organic Solar Cells. Adv. Mater. 2023, 35 (35), 2302452.
(4) Ghosh, P.; Alvertis, A. M.; Chowdhury, R.; Murto, P.; Gillett, A. J.; Dong, S.; Sneyd, A. J.; Cho, H. H.; Evans, E. W.; Monserrat, B.; Li, F.; Schnedermann, C.; Bronstein, H.; Friend, R. H.; Rao, A. Decoupling Excitons from HighFrequency Vibrations in Organic Molecules. Nature 2024, 629 (8011), 355–362.
(5) He, C.; Li, Z.; Lei, Y.; Zou, W.; Suo, B. Unraveling the Emission Mechanism of Radical-Based Organic LightEmitting Diodes. J. Phys. Chem. Lett. 2019, 10 (3), 574–580.