Organic semiconductors for semi-transparent photovoltaics
Organic photovoltaics (OPVs) have made incredible progress in the last five years, approaching a power conversion efficiency of 19% and counting. They are fantastic candidates for novel photovoltaic applications due to being easily processed, cheap, flexible, and having a tailorable absorption spectrum to optimise for semi-transparent solar windows. Their recent progress has largely been thanks to the development of what are called ‘fused ring electron acceptor’ (FREA) molecules. We have made key contributions to understanding intrinsic free charge generation and exciton transport in these materials, as well as in other novel organic semiconductors (see our paper published in Science in 2018). These studies help us in our goal of improving on what is called the ‘bulk heterojunction’ design of organic photovoltaics, and moving to simpler and better-optimised device architectures. Currently, we have projects focussed on:
- Ultrafast spectroscopy to quantify intrinsic free charge generation and exciton transport in novel organic molecules.
- New materials development – in collaboration with synthetic chemists, we are modifying fused-ring electron acceptors to improve their photovoltaic properties.
- Novel device architectures for organic photovoltaics and photodetectors.
Metal halide perovskites, and hybrid organic-inorganic materials for lasing, spectral conversion and LEDs.
Metal halide perovskites have rapidly become one of the most studied semiconductors in the world since their demonstration of remarkable photovoltaic properties in 2011. We have been at the forefront of understanding their remarkable photovoltaic and light emitting properties – helping to demonstrate the first 3D perovskite LED, and optically-pumped perovskite laser. We continue to work on novel applications and photophysics of these and hybrid nanomaterials, particularly focussing on new types of microlasers, such as whispering gallery mode perovskite systems.
Spectroscopic methods
Ultrafast transient absorption is a powerful technique for studying photophysical processes on femto-milli-second timescales. We have made important innovations and modifications to improve how this technique can be used. Alongside other ultrafast and steady-state spectroscopies – such as optical-pump terahertz probe, and time-correlated single photon counting measurements– we continue to work to improve our non-invasive spectroscopic tools for quicker, and more detailed materials characterisation.
