This afternoon, we are progressing with the general scheme of topics with the session EP1.5 Excitons in Organic and Hybrid Systems II of our Symposium EP1. Important: We have one additional speaker in the afternoon: Klaus Meerholz – his talk got shifted from Friday to this session. The following topics we will see:
- NIR EL from surface plasmons
- Area light-emitting transistors
- Multiple FRET pathways
- Topological phases in organic materials
- Manipulating Excitons with plasmonic nanoantennas
- Singlet exciton fission
- Real time exciton diffusion mapping
- Organic memory devices
Our invited speakers for the afternoon are Jana Zaumseil, Joel Yuen-Zhou, Gleb M. Akselrod, and Klaus Meerholz.
See you in a bit!
Organic electronic devices such as solar cells and light-emitting diodes convert between photons and charges (and vice versa) via intermediate, localized states: the excitons. It is the localized nature of the fundamental electronic excitation of organic semiconductors that make them prone to bimolecular annihilation processes. In this paper, Nanostructured Singlet Fission Photovoltaics Subject to Triplet-Charge Annihilation, we investigate the interaction between triplet excitons and charges (or more precisely polarons) in archetypical, state-of-the-art singlet fission photovoltaic cells. This understanding is crucial because singlet fission, capable of generating multiple excitons per incident photon, solely relies on the formation and consecutive dissociation of long-lived, dark triplet excitons.
Singlet exciton fission – a process found in special organic semiconductors – splits a high energy singlet state, which is created upon photon absorption, into two, low-energy triplet states of equal energy. Incorporating such organic materials in a photovoltaic cell paves the way to more carriers produced per incident photon flux.
Based on the singlet fission archetype material pentacene, in an exciton confining architecture around a heterojunction with the fullerence acceptor C60, we (Congreve et al., Science 340, 334 (2013)) have demonstrated an external quantum efficiency of an organic solar cell exceeding 100%, breaking the barrier of one electron per photon in the visible spectrum.