Research

Quantum Dot

​Quantum dots (QDs) are semiconductor particles a few nanometres in size, having optical and electronic properties that differ from larger particles due to quantum mechanics. They are a central topic in nanotechnology. When the quantum dots are illuminated by UV light, an electron in the quantum dot can be excited to a state of higher energy. In the case of a semiconducting quantum dot, this process corresponds to the transition of an electron from the valence band to the conductance band. The excited electron can drop back into the valence band releasing its energy by the emission of light. This light emission (photoluminescence) is illustrated in the figure on the right. The color of that light depends on the energy difference between the conductance band and the valence band, or transition between discretized energy states when band structure is no longer a good definition in QDs. 

Perovskite

​A perovskite is a material that has the same crystal structure as the mineral calcium titanium oxide, the first-discovered perovskite crystal. Generally, perovskite compounds have a chemical formula ABX3, where ‘A’ and ‘B’ represent cations and X is an anion that bonds to both. A large number of different elements can be combined together to form perovskite structures. Using this compositional flexibility, scientists can design perovskite crystals to have a wide variety of physical, optical, and electrical characteristics.  Perovskite crystals are found today in ultrasound machines, memory chips, and now – solar cells.

Nanoplatelets

​Colloidal nanoplatelets (NPLs) form a class of twodimensional semiconductor nanomaterials which differs from systems such as quantum dots (QDs) and nanorods (NRs) mainly because of the strong quantum confinement acting in only one dimension. The extended lateral dimensions of the NPLs lead to an in-plane coherent motion of the exciton, which gives rise to a so-called giant oscillator strength (GOST). They can be synthesized with a thickness controlled with monolayer precision. Hence, NPLs yield enhanced optical properties compared to zero-dimensional (0D) QDs, such as sharp band-edge transitions, narrow emission peaks, and fast exciton recombination rates. Because of their unique shape, NPLs display improved packing density and can be assembled as long chains and needles, favoring ultrafast energy transfer, while their suppressed Auger recombination has already categorized them as an efficient gain material for lasing. Furthermore, NPLs are appealing because of their high surface to volume ratio, enabling optical sensor applications, and a high two-photon absorption cross section, which categorizes them as promising candidates for two-photon imaging and nonlinear optoelectronics.