The Optoelectronics Group researches the materials and device physics of low-temperature processible, molecular semiconductors and conjugated polymers and hybrid organic-inorganic heterostructures between such organic semiconductors and inorganic semiconductors, such as nanoparticles, metal oxides and metal halide perovskites. These materials are of growing interest for a range of emerging technological applications, including energy-efficient light-emitters, low-cost, large area photovoltaics and other energy applications and flexible electronics. The research is focussed on discovering and understanding novel fundamental physical phenomena that are unique to these materials and could form the basis for new device concepts and more sustainable optoelectronic technologies.
Organic semiconductors offer fundamentally new approaches to harvest energy from the sun more efficiently. One approach that is enabled by the unique photophysics of these materials is the process of singlet fission, which causes one singlet (spin-0) photoexcitation to split into two triplet (spin-1) excitations. If these triplet excitation are suitably ionised two electron-hole pairs are generated per incident photon. This approach to carrier multiplication in photovoltaic devices has the potential of beating the fundamental Shockley-Queisser limit for the efficiency of photovoltaics cells. Another avenue of research was opened up by the recent discovery of unexpectedly clean interfaces between organic and inorganic semiconductors, in particular between organic-inorganic perovskite semiconductors or inorganic semiconductor nanoparticles and organic semiconductors. These will enable a new generation of efficient hybrid light-emitting and photovoltaics devices. We are also interested in exploring novel methods for self-organisation of molecular systems, in particular the use of DNA self-assembly for creating artificial molecular architectures with precisely defined molecular arrangement mimicking the properties of natural light-harvesting systems or the use of DNA-coated colloids for applications in photonics and batteries. Finally, the recent realisation of disorder-free organic semiconductors with significantly enhanced charge transport properties has overcome a longstanding limitation of organic materials and is opening up new opportunities for printed electronic applications that require high performance, but also for investigating hitherto not widely studied physical properties of these materials. We see significant scientific opportunities to investigate organic semiconductors in the field of spintronics and in thermoelectrics.