Engineering Optoelectronics and Smart Sensors Leveraging Metal-Organic Framework Materials

A summary of the project:
The research is in the field metal-organic framework (MOF) materials, a class of hybrid inorganic-organic compound with tuneable physical and chemical properties. The focus is on the design, fabrication, and engineering of optical sensing materials and their subsequent integration into multifunctional devices for the detection of different stimuli, ranging from chemical vapours to mechanical stresses. The results could yield smart sensors with extreme sensitivity and selectivity targeting real-world applications. This project falls within the EPSRC research areas: Sensors and instrumentation; Photonic materials; Materials engineering - composites.

The objectives of the project encompass the following aspects:
(i) Implementation of state-of-the-art nanoanalytical techniques to characterise MOF structures. Scattering-type scanning near-field optical microscopy (s SNOM), in combination with nano-Fourier infrared spectroscopy (nanoFTIR), these non-destructive techniques will enable the local scale characterisation of framework structures in both crystalline and amorphous MOF materials.
(ii) Identification and probing of structural defects in fine-scale crystalline materials. The aim is for understanding the evolution of crystal growth induced defects, and the elucidation of the mechanical behaviour at the nanoscale. Structure-mechanical property relationships will be established through tip force microscopy, in conjunction with theoretical calculations using density functional methods.
(iii) Tuning of photophysical and sensing properties by leveraging the concept of Guest@MOF confinement at the nanoscale. The porous MOF will act as a "host" structure to incarcerate a luminescent "guest" molecule. The resultant "composite" will be studied for surface adsorption effect versus true encapsulation in the MOF pore, addressing a major challenge in the field of Guest@MOF composite materials.

The project will be carried out in collaboration with the large science facilities based in Harwell, namely Diamond Light Source (beamline B22 MIRIAM) and ISIS Neutron & Muon Source (TOSCA). In situ synchrotron and neutron vibrational spectroscopy will be applied to track the real-time response of Guest@MOF crystals subject to chemical and physical stimuli when irradiated by a broadband infrared/neutron source. For example, low concentration dosing of acetone will cause host-guest interactions to enable the study of basic sensing mechanisms. Collectively, the findings of this project will help guide the design and engineering of ppm-sensitive sensors for detecting vapours of volatile organic compounds. The results may also benefit the field of optoelectronics for lighting and smart devices.