MChem University of Wales Swansea
PhD University of Wales Swansea
Functional Photoactive Materials
My research uses materials chemistry to design functional soft materials (e.g. polymers, surfactants, colloids/nanoparticles, organic-inorganic hybrids) which absorb, produce or respond to light. Such materials are the basis of many cutting-edge technologies, including light-emitting displays, solar cells, optical sensors and bioelectronic devices. I am particularly interested in developing methods to control the structural organisation of photoactive materials, from the nano- to the macroscale, since this controls many of their fundamental properties, for example, photoluminescence and charge transport. My research is highly interdisciplinary and we use a range of spectroscopy, scattering (light/neutrons/X-rays) and microscopy techniques to unravel structure-property relationships in a variety of systems.
Spectral converters for enhanced solar energy conversion
Single junction photovoltaic cells fail to achieve their theoretical efficiency due to an inability to harness all wavelengths of the solar spectrum. Spectral losses may be overcome through the addition of a spectral converter coating to the surface of a finished solar cell, which, through a photoluminescence process, converts solar photons into wavelengths suitable for use. While suitable spectral conversion lumophores are easily identifiable from studies in solution, translation of their potency to solid-state devices is often challenging. To tackle this, we are investigating the bottom-up design and fabrication of new photoactive organic-inorganic hybrid spectral converters, which exhibit tuneable spectral, optical, elastic and mechanical properties in the solid-state and can be tailored to improve the performance of different classes of solar cell.
Interfacial materials for organic electronic devices
Interface modifying materials are commonly used to improve charge extraction and contact between the active layer and the electrodes in multilayer organic electronic devices. However, while the role between the morphology and optoelectronic properties of the active layer are understood, the analogous relationships in the interfacial modifying layers are still under debate. We exploit the bottom-up self-assembly of soft materials (e.g. polyelectrolytes, surfactants) in solution to design interfacial layers with intricate nanostructural organisation and correlate this to their performance in optoelectronic devices.
Stimuli-responsive materials exhibit a change in their structure, conformation, chemical or physical properties in response to an external signal, e.g. light, pH, temperature. These materials find application in a variety of fields including drug delivery, sorting and purification of substrates, and sensing. Our research is focussed on the design of photoactive lyotropic liquid crystal phases which can be used as responsive templates for the synthesis of nanomaterials with a high internal porosity for use in catalysis and environmental remediation of pollutants.
A large area luminescent solar concentrator delivers energy down-shifted solar simulated light to edge-bound silicon solar cells.
- B. McKenna and R. C. Evans*, Towards efficient spectral converters through materials design for luminescent solar devices, Adv. Mater. (2017), DOI: 10.1002/adma.201606491
- A. Kaniyoor, B. McKenna, S. Comby, R. C. Evans*, Design and response of high-efficiency planar doped luminescent solar concentrators using organic-inorganic di-ureasil waveguides, Adv. Opt. Mater., 4, 444-456 (2016)
- N. Willis-Fox, A.-T. Marques, J. Arlt, U. Scherf, H. D. Burrows, L. D. Carlos and R. C. Evans*, Synergistic photoluminescence enhancement in conjugated polymer-di-ureasil organic-inorganic composites, Chem. Sci., 6, 7227-7237 (2015).
- M. Chevrier, J. E. Houston, J. Kesters, N. Van den Brande, A. E. Terry, S. Richeter, A. Mehdi, O. Coulembier, P. Dubois, R. Lazzaroni, B. Van Mele, W. Maes*, R. C. Evans* and S. Clément*, Self-assembled conjugated polyelectrolyte-surfactant complexes as efficient cathode interlayer materials for bulk heterojunction organic solar cells, J. Mater. Chem. A, 3, 23905-23916 (2015)