Efficient Solid-State Photon Up-conversion via Charge Transfer States and Triplet-Triplet Annihilation in Molecular Heterojunctions

by Prof. Ajay K. Pandey (School of Electrical Engineering and Robotics, Queensland, University of Technology, Australia)

Thursday 17 Jul 2025, 14:30 → 16:30 Asia/Kolkata

AG 66

Photon interconversion in semiconductors is of fundamental importance for digital imaging and quantum sensing. Nonlinear processes such as triplet-triplet annihilation (TTA) offer photon up-conversion at yields desired for solid-state optoelectronic devices. In this talk, I will present multilayer molecular systems where absorption of near-infrared (NIR) photons results in production of visible photons. Time-resolved photoluminescence, transient absorption spectroscopy, and magnetic field dependent photoluminescence measurements will be discussed to establish a detailed balance of photoexcited states and formation of charge transfer states of triplet character (3CT), working in tandem in feeding the molecular triplet state population. The mechanism unlocks design of new energy cascades for up-conversion with relatively high quantum yields at modest light intensities and bears great promise for the technological implementation of photon up-conversion in deployable optoelectronic devices.