RESEARCH


Our Vision

Over the next two decades the world faces the challenge and opportunity of completely transforming the way we generate and use energy. An exciting new range of “energy materials” and devices are being studied and developed to meet these challenges. However, there are fundamental differences between the well-ordered crystalline materials, such as Si, which have underpinned the information and communication revolution of the previous decades and the next generation of energy materials and devices, that must enable the coming energy transformation. These new systems are often disordered, contain complex buried interfaces, are controlled by the flow of various particles and quasiparticles at the nanoscale and have properties that are strongly controlled by vibrational coupling and defects. Our vision is to catalyse a new era in the study of energy materials by elucidating the electronic and structural dynamics and nanoscale transport of charges, excitons, phonons and ions with unprecedented spatial and temporal precision, across a range of energy materials from photovoltaics and LEDs to batteries and thermoelectrics. We seek to provide fundamental insights into the physics of disordered nanoscale materials and use these insights to develop strategies and device concepts that can bring radical new functionalities beyond current physical limits.

Ultrafast Spectroscopy - Elucidating Quantum Dynamics

The motion and dynamics of charges, excitons and phonons control the properties of a range of semiconductor and quantum materials. Using various ultrafast spectroscopy techniques with time resolution down to 10fs we study exciton, charge and phonon dynamics in these systems with unprecedented sensitivity. This has allowed us to unravel a host of interesting physical phenomena, such as ballistic charge propagation in molecular systems, the quantum mechanics of singlet exciton fission and exciton-phonon coupling in semiconductors. Learn more via the links below:

Schnedermann et al, Nature Comms (2019), Read more

Jakowetz et al, Nature Materials (2017), Read more

Stern et al, Nature Chemistry (2017), Read more

Bakulin et al, Nature Chemistry (2016), Read more

Musser et al, Nature Physics (2015), Read more

Gélinas et al, Science (2014), Read More 

 

Ultrafast Microscopy

Traditionally ultrafast spectroscopy has been conducted on large ensembles. But the motion of photoexcitations at the nanoscale is crucial to much of the physics of many systems. A recent breakthrough has allowed us combine for the first time the powerful techniques of ultrafast spectroscopy and super-resolution optical microscopy. We can now track the motion of excitons, charges, polaritons, plasmons and other quasi-particles with 10fs temporal-resolution and 10nm spatial-resolution. This unprecedented combination of temporal and spatial resolution opens a completely new window into nanoscale quantum phenomena in solid-state systems. 

Sung et al. Nature Physics (2019), Read More

Nanomaterials and devices

We design and fabricate nanomaterials, including lanthanide-doped nanoparticles,  colloidal quantum dots and hybrid organic-inorganic systems. We explore the photophysics of these systems using our ultrafast spectroscopy toolkit and also explore their use in next generation of electronic and photonic devices, such as photovoltaics that could break the Shockley-Queisser limit. 

Han et al., Nature (2020), In Press

Tabachnyk et al. Nature Materials (2014), Read More

PVs Beyond the Shockley-Queisser Limit

A “photon multiplier” based on singlet fission: Our demonstration of efficient triplet transfer across the organic/inorganic interface opens the door to an all-optical method of utilising the triplet excitons generated via fission, effectively converting a carrier multiplication process into a photon multiplication process. The basic scheme of such a “Photon-Multiplier” is shown in Figure 3 and consists of a thin film of a SF material of appropriate band gap and triplet energy doped with a small amount of inorganic nanocrystals. The device function as follows: light absorption creates singlet excitons (1) that rapidly undergo SF to form two triplet excitons (2). The triplets then diffuse and undergo efficient triplet transfer into the nanocrystals (3). The electron-hole pairs in the nanocrystals can then recombine radiatively, emitting two low-energy photons for each high-energy photon absorbed (4). The emitted photons are then absorbed in a conventional solar cell onto which the photon multiplier is coated or laminated.

Rao et al, Nature Reviews Materials (2017), Read more

Tabachnyk et al. Nature Materials (2014), Read More