Colloidal quantum dots (CQDs) and related materials are nanoscale semiconductor crystals that represent an exciting frontier in solution-processed materials. Their size-tuneable optical properties and unique quantum behaviour make them highly versatile for advanced photonic applications, including solar cells, light-emitting diodes (LEDs), high-speed colour converters for displays and lighting, lasers, and single-photon sources.
This PhD project builds on recent advances in the synthesis, assembly, and characterization of CQDs organized into supracrystals—hierarchical structures where nanocrystals act as building blocks or “nanobricks.” 1-2 Supracrystals are highly ordered, densely packed assemblies that exhibit emerging collective optical behaviours, including enhanced fluorescence and laser oscillation. Our team has developed emulsion-templated self-assembly processes to fabricate semiconductor supracrystals from the bottom up, successfully demonstrating microlasers produced in this way. In parallel, we are exploring hybrid structures and top-down fabrication methods to expand the design space.
A key focus of our current efforts is the creation of multifunctional supraparticles (SPs) by blending different types of nanobricks. We are tailoring the geometry and design of SPs, e.g. coupling them to plasmonic structures or upconverting nanoparticles, and engineering their surface chemistry to unlock new functionalities. Recent achievements include SP microlasers functionalized with biomolecular probes, SPs coupled to optical waveguides, and assemblies capable of emitting at multiple wavelengths. Building on this foundation, we are now extending our approach to a broader range of materials and applications.
The overarching goal of this PhD project is to fabricate and study quantum-dot SPs with superior light emission properties, aiming to advance the state of the art in temporally controlled, ultra-bright microscopic photonic sources. If successful, the outcomes could have significant impact across optical communications, biological and chemical sensing, photocatalysis, and quantum photonics.
The project will pursue three key objectives:
Synthesis and characterization of CQDs and supracrystals: The student will develop and refine protocols for synthesizing CQDs and directing their controlled self-assembly into hybrid supracrystals.
Studies of fluorescence, laser oscillation, and non-classical emission: By carefully designing supracrystals, the researcher will demonstrate fluorescence enhancement and target laser oscillation with reduced thresholds, enabling efficient microscopic laser sources for both classical and quantum applications.
Investigation of non-toxic CQD materials: To address environmental concerns associated with cadmium- or lead-based CQDs, the project will explore alternative, less toxic materials, assessing whether they can match the performance of conventional systems while contributing to safer, sustainable photonic devices.
Depending on the candidate’s interests, there will be opportunities to explore applications such as biological and chemical sensing, optical communications, or single-photon sources.3 The student will join the Colloidal Photonics team at the Institute of Photonics, which develops novel technologies for medicine, environmental monitoring, industry, and digital lighting. This interdisciplinary environment will provide a strong foundation for mastering quantum dot synthesis, functionalization, and assembly.
By leveraging expertise in nanoscale control and material design, this project will push the boundaries of what is possible with colloidal quantum dots, paving the way for more efficient, robust, and scalable photonic devices.