Wed, 14 Jun 2023
Events
Email
Print

Dr. Eli Zysman-Colman

University of St Andrews

Design of multiresonance thermally activated delayed fluorescence materials for organic light-emitting diodes (and beyond)

Wednesday, June 14, 2023
SSB 7172 @ 3:30 p.m.

Host: Dr. Daniel Leznoff

 

Abstract

The first-generation OLEDs were based on organic fluorescent emitters. Their efficiency was intrinsically capped at 25% due to only being able to recruit singlet excitons. The second generation OLEDs have employed organometallic phosphorescent emitters, which harvest both singlet and triplet excitons for emission due to the enhanced intersystem crossing mediated by the heavy metals such as iridium(III) and platinum(II). These metal complexes possess very desirable optoelectronic properties and lead to very efficient OLED devices.  However, the scarcity of these metals, their high cost and their toxicity are important detracting features. The third generation OLEDs are based on small organic compounds that emit via a thermally activated delayed fluorescence (TADF) mechanism.  As with phosphorescent emitters, OLEDs using these emitters can recruit 100% of the excitons. In Donor-Acceptor TADF compounds, the emission is broad to the charge transfer character of the emissive singlet state. Multiresonant TADF emitters on the other hand show significantly narrower emission.  In this presentation, I will discuss our recent efforts towards the design of multiresonant TADF emitters, including designs that break the orthodoxy of boron-nitrogen doped triangulene structures.

The first-generation OLEDs were based on organic fluorescent emitters. Their efficiency was intrinsically capped at 25% due to only being able to recruit singlet excitons. The second generation OLEDs have employed organometallic phosphorescent emitters, which harvest both singlet and triplet excitons for emission due to the enhanced intersystem crossing mediated by the heavy metals such as iridium(III) and platinum(II). These metal complexes possess very desirable optoelectronic properties and lead to very efficient OLED devices.  However, the scarcity of these metals, their high cost and their toxicity are important detracting features. The third generation OLEDs are based on small organic compounds that emit via a thermally activated delayed fluorescence (TADF) mechanism.  As with phosphorescent emitters, OLEDs using these emitters can recruit 100% of the excitons. In Donor-Acceptor TADF compounds, the emission is broad to the charge transfer character of the emissive singlet state. Multiresonant TADF emitters on the other hand show significantly narrower emission.  In this presentation, I will discuss our recent efforts towards the design of multiresonant TADF emitters, including designs that break the orthodoxy of boron-nitrogen doped triangulene structures.

Presenting Author's Biography (from group site)

Eli Zysman-Colman was born in April of 1975 in Montreal, Québec, Canada. He received his BSc in physics from McGill University in 1998.  He completed his doctorate in chemistry at McGill University under the supervision of Prof. David N. Harpp. There he studied the physical properties and isomeric relationships of polychalcogens: Notably dialkoxy disulfides, thionosulfites and polysulfides. After obtaining his PhD  in 2004, Eli started as a FQRNT postdoctoral fellow at the Organisch-chemisches Institut at the Universität Zürich in Zürich, Switzerland with Prof. Jay S. Siegel. The primary focus of his work there was the total synthesis of a molecular trefoil knot. Eli then moved to Princeton University in 2006 to work with Prof. Stefan Bernhard in the chemistry department as a PCCM fellow. While at Princeton, Eli worked on improving the design of light emitting electrochemical cells (LEECs) through ligand modification about iridium complexes. Eli began as an Assistant Professor in the Department of Chemistry at the Université de Sherbrooke in July, 2007. In 2013 Eli moved his research group to the School of Chemistry at the University of St Andrews where he is presently Professor of Optoelectronic Materials, Fellow of the Royal Society of Chemistry and is the holder of a Royal Society Leverhulme Trust Senior Research Fellowship. His research program focuses on the rational design of: (I) luminophores for energy-efficient visual displays and flat panel lighting based on organic light emitting diode (OLED) and light-emitting electrochemical cell (LEEC) device architectures; (II) sensing materials employed in electrochemiluminescence; and (III) photocatalyst developing for use in organic reactions.

Website: http://www.zysman-colman.com/