In the Photonics Nanoaterials Group we are interested in colloidal nanoparticles that interact with light and convert it into useful forms of energy. The group is focused on the development of a synthetic toolbox for the fabrication of complex, functional nanocrystals, as well as spectroscopic investigation of the structure/property relationships in these systems. The central motif of our research is the heterointerface at the contact between two nanomaterials, which is often the spawns new, emergent properties that are absent in the individual components.

We have done extensive work to understand the role of small, atomically defined intermediates, so called magic-size clusters, on the shape- and regio-selectivity in nanocrystal formation. The ultrasmall nanoparticles are not only interesting as nanomatrials with a defined well-size, they also act as reservoirs that regulate the distribution and flux of material as nanoparticles grow.

With the synthetic toolbox we have synthesised nanoparticles with a high degree of uniformity, including nanorods with a single, defined tip and bristled metal/semiconductor aggregates with a high potential for heterogeneous photocatalysis.

We are using ultrafast optical spectroscopy to follow the directional processes inside these complex nanostructures. In these pump/probe experiments the sample is disturbed with a short laser pulse and its respond is detected by a second pulse after a variable time delay. With that we elucidate the charge carrier dynamics across a heterojuntion. In the case of, e.g., the CdS/CdTe interface, multiple factors lead to a charge trapping that can be switched using chemical stimuli. Using a combination of optical, X-ray, and Raman spectroscopy we quantify the extent of graded interfaces on the nanometre scale and measure the delocalisation of excited charge carrier pairs.

Agilent Cary 60 UV/vis Absorption Spectrometer

• 190-1100 nm detection range
• photometric range up to 4 Abs

Horiba FluoromaxPlus Photoluminescence Spectrometer

• 190-980 nm detection range (UV/vis)
• 1950-1700 nm detection range (NIR, Peltier-cooled)
• TCSPC unit with 405 nm excitation laser (300 mW, 45 ps pulse length)
• Polariser

Vigor Nitrogen Glove Box

• 2 glove ports
• Freezer (-35°C)