Harnessing triplet excitons in organic solid-state lasers

Speaker: Atul Shukla
Affiliation: University of Queensland

Abstract

Organic semiconductors have the ability to show efficient electroluminescent (EL) characteristics and can also provide light amplification under optical excitation. However, even after decades of extensive research, realisation of electrically pumped organic lasers has been a difficult task. This is primarily due to the excessive build-up of triplet excitons under electrical excitation leading to disproportionate ratio between the population of triplet and singlet excitons. While these triplet excitons are by themselves non-emissive, they also lead to non-radiative depletion of singlet excitons by process known as singlet-triplet annihilation. In this talk I will discuss about technique that can aid towards constructive use of triplet excitons and present results that show light amplification under optical pumping and EL external quantum efficiency (EQE) of ~8% which exceeds the theoretical spin statistical limit of 5%  as described for typical fluorescent organic semiconductors.