Responsive Quantum-Dot–Polymer Composites for Physical, Chemical and Biological Sensing

PGR-P-2523

Key facts

Type of research degree: PhD
Application deadline: Monday 30 November 2026
Project start date: Thursday 1 April 2027
Country eligibility: International (open to all nationalities, including the UK)
Funding: Non-funded
Supervisors: Dr Kevin Critchley
Additional supervisors: Stephen D Evans
Schools: School of Physics and Astronomy
Research groups/institutes: Molecular and Nanoscale Physics

<h2 class="heading hide-accessible">Summary</h2>

Quantum dots are highly fluorescent nanomaterials whose emission can be altered by changes in their surrounding environment. Embedding quantum dots within polymers offers a versatile route to creating flexible and responsive sensors, because the polymer can provide mechanical properties, analyte transport, chemical selectivity and protection of the quantum dots. This PhD project will investigate how quantum-dot–polymer composites can be designed for physical, chemical and biological sensing. The overall aim is to establish how polymer composition, quantum-dot surface chemistry and nanoscale structure control the optical response of the material. The student will prepare quantum-dot-containing polymer films, elastomers and potentially hydrogels, varying factors such as quantum-dot concentration, surface ligands, polymer chemistry, crosslinking, porosity and processing conditions. The resulting materials will be characterised using fluorescence spectroscopy, fluorescence lifetime measurements, atomic force microscopy, electron microscopy and mechanical testing. Initial work will examine how the distribution and local environment of quantum dots within a polymer affect their optical properties. The project will then explore sensing mechanisms including changes in fluorescence intensity, emission wavelength, lifetime, energy transfer and quenching. Potential applications include the detection of strain, pressure, temperature, mechanical damage, pH, ions, small molecules and biologically relevant analytes. Biosensing approaches may involve responsive polymers or recognition components such as enzymes, peptides, aptamers or functional surface groups. The precise sensing targets will be selected according to the student’s interests, initial results and the most promising material platforms. The project will combine fundamental studies of nanomaterial–polymer interactions with the development of proof-of-concept sensors. Sensor performance will be assessed through sensitivity, selectivity, response time, reversibility, reproducibility and long-term stability. This interdisciplinary project would suit a student interested in nanomaterials, polymers, photophysics, spectroscopy, microscopy or sensor development. It will provide training across materials preparation, optical characterisation, nanoscale imaging, data analysis and experimental design, while allowing the student to develop the project towards physical sensing, environmental monitoring or biosensing.

<h2 class="heading hide-accessible">Full description</h2>

Quantum dots are fluorescent semiconductor nanocrystals whose optical properties can be controlled through their size, composition, surface chemistry and surrounding environment. Their bright and tuneable emission makes them attractive as optical reporters, but their practical use in sensors depends on how effectively they can be incorporated into stable, processable and responsive materials. Polymers offer an especially versatile host for quantum dots. They can provide mechanical flexibility, chemical selectivity, controlled transport of target molecules and protection from the surrounding environment. They can also be designed to respond to changes in strain, pressure, temperature, pH, solvent composition or the presence of specific chemical and biological species. This PhD project will investigate how quantum dots and polymers can be combined to create responsive composite materials for sensing. The central objective is to understand how the composition and nanoscale structure of the composite control its optical response, and to use this understanding to develop proof-of-concept sensors. Research questions The project will address questions including: <ul> <li>How do polymer chemistry, crosslinking and processing conditions affect the distribution and optical properties of quantum dots?</li> <li>How does quantum-dot surface chemistry control compatibility with different polymers?</li> <li>Can aggregation or phase separation be deliberately controlled to enhance sensitivity?</li> <li>How do strain, pressure, temperature or chemical exposure alter quantum-dot emission?</li> <li>How can responsive polymers or molecular recognition elements be used to introduce selectivity towards biological targets?</li> <li>Which optical measurements provide the most reliable sensing signal: fluorescence intensity, emission wavelength, lifetime, polarisation or energy transfer?</li> </ul> Research programme The student will prepare a range of quantum-dot–polymer composite materials. Depending on the direction of the project, these may include solid films, flexible elastomers, porous polymers or hydrated hydrogel systems. Variables such as quantum-dot loading, surface ligands, polymer composition, crosslink density, film thickness, porosity and preparation conditions will be systematically controlled. This will allow relationships between processing, nanoscale structure and sensor performance to be established. A broad range of characterisation techniques will be used, potentially including: <ul> <li>steady-state fluorescence and absorption spectroscopy;</li> <li>time-resolved fluorescence and lifetime measurements;</li> <li>atomic force microscopy;</li> <li>quantitative nanomechanical mapping;</li> <li>electron microscopy;</li> <li>mechanical testing;</li> <li>optical microscopy and spatially resolved fluorescence measurements;</li> <li>surface and chemical characterisation.</li> </ul> The first stage of the project will focus on understanding how incorporation into a polymer changes quantum-dot photophysics. The student will investigate effects such as fluorescence quenching, energy transfer, changes in interparticle separation, surface passivation and the influence of the local dielectric and chemical environment. The second stage will explore sensing applications. Initial studies may involve physical stimuli such as strain, pressure, temperature or mechanical damage. These systems provide a controlled route for investigating how deformation of a composite changes the environment around the quantum dots. The project will then extend towards chemical and biological sensing. Possible targets include pH, metal ions, metabolites, enzyme activity, small biomolecules or environmentally relevant contaminants. Selectivity may be introduced through responsive polymer groups, surface functionalisation or recognition components such as enzymes, peptides or aptamers. The precise sensing targets will be selected during the project according to the most promising material systems, the student’s interests and the scientific opportunities that emerge from the early results. Sensor development Selected materials will be developed into proof-of-concept sensors. Their performance will be assessed using criteria including: <ul> <li>sensitivity and detection range;</li> <li>selectivity;</li> <li>response and recovery time;</li> <li>reversibility;</li> <li>reproducibility;</li> <li>photostability;</li> <li>mechanical and chemical stability;</li> <li>performance in realistic sample environments.</li> </ul> A key aim will be to distinguish genuine sensing mechanisms from artefacts such as changes in sample thickness, light scattering, reabsorption or irreversible material damage. The project is not intended simply to screen a large number of analytes. Instead, it will develop a mechanistic understanding of how quantum-dot–polymer interactions can be engineered to produce useful optical responses. Training and research experience The successful candidate will receive interdisciplinary training spanning nanomaterials, polymer composites, spectroscopy, microscopy and sensor development. They will gain experience in: <ul> <li>preparation and processing of nanomaterial composites;</li> <li>optical and time-resolved spectroscopy;</li> <li>nanoscale structural and mechanical characterisation;</li> <li>design of controlled sensing experiments;</li> <li>quantitative data analysis;</li> <li>interpretation of photophysical mechanisms;</li> <li>scientific writing and communication.</li> </ul> There may also be opportunities to develop custom experimental equipment, use computational modelling to support interpretation, or collaborate with researchers working in polymer science, biosensing, microscopy or materials characterisation. Project outcomes The project is expected to generate new understanding of how quantum dots behave within responsive polymer environments and how nanoscale structure affects sensor performance. Potential outcomes include: <ul> <li>design rules for stable and responsive quantum-dot–polymer composites;</li> <li>improved understanding of quantum-dot photophysics in heterogeneous materials;</li> <li>mechanically responsive optical films;</li> <li>chemical or biological sensing platforms;</li> <li>proof-of-concept devices for healthcare, environmental monitoring or smart-material applications.</li> </ul> This project would particularly suit a student who enjoys interdisciplinary research and is interested in combining fundamental materials science with practical sensor development.

<h2 class="heading">How to apply</h2>

To apply for this project you will need to make a formal application for research degree study through the <a href="https://www.leeds.ac.uk/research-applying/doc/applying-research-degrees">University website</a>. You will need to create a login ID with a username and PIN. <ul> <li>For Application type please select Research Degrees – Research Postgraduate. </li> <li>The admission year for this project is 2026/27 Academic Year. </li> <li>You will need to select your Planned Course of Study from a drop-down menu. For this project, scroll down and select PHD Statistics FT. </li> <li>The project start date for this project is from 1 April 2027, please use this as your Proposed Start Date of Research. </li> <li>Please state clearly in the research information section that the research degree you wish to be considered for is Responsive Quantum-Dot–Polymer Composites for Physical, Chemical and Biological Sensing as well as <a href="https://eps.leeds.ac.uk/physics/staff/4104/dr-kevin-critchley">Kevin Critchley</a> as your proposed supervisor.</li> </ul> More information on how to apply is available on our website <a href="https://www.leeds.ac.uk/research-applying/doc/applying-research-degrees">here</a>. You will be required to provide a personal statement which outlines your interest in the project you are applying for, why you have chosen it and how your skills map onto the requirements of the project. We welcome and strongly encourage any potential applicants to contact the supervisor(s) for an informal discussion, prior to applying, and recommend submitting your application early. Please note that you must provide the following documents in support of your application by the closing date of Monday 30 November 2026: <ul> <li>Full Transcripts of all degree study or if in final year of study, full transcripts to date including grading scheme</li> <li>Personal Statement outlining your interest in the project</li> <li>CV</li> </ul> If English is not your first language, you must provide evidence that you meet the University's minimum English language requirements below. As an international research-intensive university, we welcome students from all walks of life and from across the world. We foster an inclusive environment where all can flourish and prosper, and we are proud of our strong commitment to student education. Across all Faculties we are dedicated to diversifying our community and we welcome the unique contributions that individuals can bring, and particularly encourage applications from, but not limited to Black, Asian, people who belong to a minority ethnic community, people who identify as LGBT+ and people with disabilities. Applicants will always be selected based on merit and ability.

<h2 class="heading heading--sm">Entry requirements</h2>

Applicants to research degree programmes should normally have at least a first class or an upper second class British Bachelors Honours degree (or equivalent) in an appropriate discipline. The criteria for entry for some research degrees may be higher, for example, several faculties, also require a Masters degree. Applicants are advised to check with the relevant School prior to making an application. Applicants who are uncertain about the requirements for a particular research degree are advised to contact the School or Graduate School prior to making an application.

<h2 class="heading heading--sm">English language requirements</h2>

The minimum English language entry requirement for research postgraduate research study is an IELTS of 6.0 overall with at least 5.5 in each component (reading, writing, listening and speaking) or equivalent. The test must be dated within two years of the start date of the course in order to be valid. Some schools and faculties have a higher requirement.

<h2 class="heading">Funding on offer</h2>

This is a non funded PhD project. Applicants are expected to be self funded or to secure external funding. Important: Please note that all costs associated with your arrival at Leeds (<a href="https://www.leeds.ac.uk/international-visas-immigration/doc/applying-student-visa">visa, Immigration Health Surcharge</a>, flights etc) would have to be met by yourself, or you will need to find an alternative funding source.

<h2 class="heading">Contact details</h2>

For further information about your application, including how to apply, please contact PGR Admissions by emailing <a href="mailto:phd@engineeering.leeds.ac.uk">phd@engineeering.leeds.ac.uk</a> For further information about this project, please contact Dr Kevin Critchley by emailing <a href="mailto:k.critchley@leeds.ac.uk">k.critchley@leeds.ac.uk</a> or by calling +44 (0)113 343 3872.