The Department of Chemistry

Qualifications 

• PhD UWI (Mona) 2009
• B.Sc. (Hons) UWI (Mona)

Research 

My research involves the study of Materials for Optoelectronic Applications. The main areas include:

• Metallomesogens (Liquid Crystals)
  • Liquid crystalline (mesogenic) phenomena are observed in a wide range of areas and are a worthy topic of investigation due to technological applications in liquid crystal displays (LCD’s). In the last three decades, there have been considerable advances in characterizing the structures of various liquid crystalline phases. It is by systematic investigation of these that the viability of new liquid crystalline compounds for various applications is tested, and also, occasionally, novel behaviour uncovered, opening up the possibility of new and/or improved applications.
  • The current research involves a targeted synthesis of various novel Schiff base metal complexes and the study of their liquid crystal (thermotropic phase transition) properties by differential scanning calorimetry (DSC) and polarized light microscopy (to characterize phases). Our aim is to establish important structure-property relationships by varying hydrocarbon chain lengths on the molecules and to see the effect of these changes on molecular structure and packing interactions and how these impact phase behaviour. At the basis of this is extensive structural analysis through X-ray crystallography and diffraction, solid-state NMR and Infrared spectroscopies.
  • Another dimension involves carrying out computational calculations of electronic structure properties such as electric dipole moments to ascertain some basis of intermolecular interactions through molecular structure and electronic polarizability.
  • Similar work involves the study of metal carboxylates.

• Compound Semiconductor Thin Films
  • Semiconductor thin films based on silicon (Si), cadmium telluride (CdTe), copper indium sulphide (CIS), copper indium gallium sulphide (CIGS), etc have reached commercialization stage in photovoltaics. However, low efficiencies, restrictions on heavy metal use for Cd and limitations in supply for In and Te have raised concerns about limitations on production capacity of PV devices made from these thin films. Quaternary, compound semiconductor thin films such as Cu2ZnSnS4, (CZTS) have emerged as promising alternatives since they have abundant and environmentally friendly metals.
  • Our work involves the preparation of thin films of un-doped and doped transition metal CZTS by Aerosol Assisted Chemical Vapour Deposition (AA-CVD). Films will be extensively characterized using PXRD, SEM-EDX, TEM, AFM and an important feature will be to ascertain the effect of dopants to enable up-conversion photoluminescence using PL spectroscopy. Important photo-response studies will be conducted to ascertain a measure of the light-to-electrical energy conversion.

• Colloidal Semiconductor Nanoparticles
  • The use of compound semiconductor nanoparticles as materials for photovoltaic applications is particularly attractive since they offer enhanced and unique optoelectronic materials that bulk semiconductors do not provide. More so, effective doping of metal ions into the nanostructure of such materials can yield optimized electronic properties in addition to quantum sized effects.
  • Our research is focussed on colloidal synthesis via facile methods, using varying combinations of precursors, capping agents and temperature ranges to yield quantum dots of varying sizes and tunable optical properties of ternary and quaternary chalcogenide compounds, such as CIS. At the core of the work is an extensive characterization of structures using TEM, SEM-EDX, ICP-MS, powder X-ray diffraction to ascertain structural properties and UV-Vis and PL spectroscopies to study optoelectronic properties. We also will embark on the use of STM to study the band structures of these nanostructures, which will be essential in understanding their optical properties.
  • Important photo-response studies will be conducted to ascertain a measure of the light-to-electrical energy conversion.

• Lanthanide Metal-Organic Frameworks (Ln-MOFs)
  • The study of MOFs and coordination polymers (CPs) based on lanthanide(III) ions has attracted much attention recently. This interest lies in the promise of new functional materials that take the unique optoelectronic properties of Ln(III) ions and combine them with well-defined network connectivity of MOFs. Ln-MOFs and CPs are therefore promising for the development of materials with tunable properties for solid-state light, sensing, catalysis, communication and imaging, etc.
  • This work conducted in conjunction with Dr Marvadeen Singh-Wilmot at the Department of Chemistry UWI, Mona Campus (primary investigator), involves design and reticular synthesis of Ln-MOFs using a range of di-carboxylates as ligands (linkers). This approach has yielded varying novel Ln-MOFs of similar topologies through a tertiary building unit (TBU) concept. The deliberate tuning of the optical properties via doping is interesting and the prospects of making nanosheets via a “Top-down” sonicating nano-exfoliation process of the CPs are very promising.
  • The work involves extensive structural characterization using X-ray crystallography and diffraction and luminescent properties probed via PL spectroscopy.