Thursday, 16 November 4:00pm – 5:00pm

This seminar will be delivered in Chemistry Lecture Theatre 4

Speaker: Dr Andrew Danos, Durham University

Host: Prof. Merefith Jordan

Abstract: Managing the spin of excited states is vital for unlocking high performance in organic semiconductor applications. Electron-hole pairs with aligned spin give rise to triplet states that are often non-emissive though, with radiative decay lifetimes in the range of microseconds or longer. These properties contrast to singlet excited states with anti-aligned electron spin pairs, having lifetimes in the picosecond-nanosecond range. In Organic Light Emitting Diodes (OLEDs), random recombination of electrons and holes results in 75% formation of triplet excitons, severely limiting achievable efficiencies.

Alongside more established organometallic phosphorescent emitters, metal-free donor-acceptor materials featuring Thermally Activated Delayed Fluorescence (TADF) have recently emerged as a promising way to harvest triplet states for emission in OLEDs. While TADF can achieving high-efficiencies and even deep-blue emission, it is also highly demanding in terms of host material properties and molecular design. In this talk recent work to better understand the TADF process and successfully apply it to OLEDs will be presented, as well as introducing more advanced strategies that rely on energy transfer to overcome some of the intrinsic limitations of TADF emitters.

Bio: Andrew did his undergraduate and Honours degree within the School of Chemistry at the University of Sydney before completing a PhD at the University of NSW, investigating triplet-triplet annihilation as a way to upconvert photon energy and improve the efficiency of solar cells. Andrew then moved to Durham University in the UK and he is currently an ECR in the School of Physics working in photonics, with a particular interest in thermally activated delayed fluorescence (TDF) and its application to organic light emitting diodes (OLEDS). Recently, Durham has awarded Andrew funding for a research speaking tour across Australian universities.