The development of organic semiconductors has the potential to revolutionise the design and fabrication of future optoelectronic devices. Such devices cover a wide range of applications and include solar cells, sensors, light-emitting diodes, and lasers. Optimising the performance of these devices poses a significant challenge, as each is the product of multiple physical processes, typically occurring on timescales ranging from femtoseconds to milliseconds. We use time-resolved spectroscopic methods such as transient absorption and transient photoluminescence to probe the photophysical properties of organic semiconductors and gain a detailed understanding of how these materials “work”.
Our research has a strong application-focus across the three following areas.
Fluorescence-based chemical sensors
Rapid and reliable detection of chemical threats remains one of the most pressing security challenges faced today. Fluorescence-based sensing is one of the most attractive solutions to this problem because it can achieve high sensitivity in a handheld device. My research lies in the development of novel lumines- cent sensor materials and understanding how their performance is related to their photophysical properties and physical properties.
Research topics include:
explosives and taggant detection,
chemical warfare agent detection,
methods for achieving selectivity,
sensing platform development,
identifying the nature of the quenching interaction in thin films,
characterisation of diffusion of organic vapours into thin films, and
improving vapour penetration through film patterning.
Organic and hybrid solar cells
The next generation of solar cells based on organic and hybrid semiconductors can be solution processed over large areas leading to panels that are cheaper than current technology as well as being lighter and flexible. The performance of these systems is intimately related to the photophysical characteristics of the materials and optical spectroscopy is ideally suited to probing these materials.
Research topics include:
exciton diffusion in light harvesting materials,
factors controlling free charge generation at interfaces, and
single component active layers for solar cells.
Emissive processes in organic light-emitting diodes
Organic semiconductors can be highly luminescent and there currently exists a broad palette of materials available for use in both display and lighting applications. These applications are currently the two biggest emerging markets for organic semiconductors and both require high efficiency devices that can consistently deliver high brightness.
Research topics include:
quantifying bimolecular interactions between singlet and triplet excitons and charge carriers,
identifying energy transfer pathways between emitters, and
understanding the emissive process in the latest generation of materials.