RESEARCH IN NANOCRYSTALS & NANOWIRES

Nanotechnology Research Group

The Nanotechnology  Research Group at the Materials and Surface Science Institute (MSSI) is led by Dr. Kevin M. Ryan, Senior Lecturer in Inorganic Chemistry and Chemical Nanotechnology, Course Director Pharmaceutical and Industrial Chemistry at the Department of Chemical and Environmental Sciences (CES), University of Limerick.  Previous affiliations included Marie Curie Fellowship positions at the University of California, Berkeley, USA and Merck Chemicals Southampton, UK following  BSc and PhD degrees at University College Cork. The group research Interests are in Semiconductor Nanocrystals and Nanowires with emphasis on Synthesis, Assembly and Device Applications in Energy Storage and Energy Conversion Applications. The group also studies nucleation and growth in both hard (metal, semiconductor) and soft (pharmaceutical) nanocrystal materials with emphasis on size, shape and crystal phase control.
Address: MS1019, University of Limerick, Limerick Ireland. Phone: + 353 (61) 213167,  Email: kevin.m.ryan(at)ul.ie.

Research and Affiliation Links

Research Group:

The research group currently (2013) consists of 3Postdoctoral Researchers and 9 PhD students.

Front row Tadhg Kennedy, Kumaranand Palaidappan, Michael Brandon, Martin Sheehan, Jianjun Wang, Michael Bezeuidenhout. Back row: Claudia Coughlan, Emma Mullane, Kevin Ryan, Shalini Singh, Louise Barry, Pai Liu. Not in picture Grace Flynn.

Research Overview:

Keywords: Colloidal Nanocrystals, Nanorods, Nanowires, Silicon, Germanium, Cadmium Sulphide, Cadmium Selenide, Copper Indium Gallium Sulphide/selenide (CIGS), Dicopper-zinc-tin-tetrasulphide (CZTS), Nanorod Assembly, Electrophoretic Assembly, Charge based Assembly, Thin-films, Photoabsorbers, Lithium ion batteries. 

The group research interests are in:  [1]  Colloidal Nanocrystals  with particular emphasis on Semiconductor Nanorods   (Fig A) and their  device scale assembly by directed (Electric fields Fig B) or non-directed for scaleable applications in photovoltaics. (See video for overview of this technology)  The group has pioneered routes whereby the nanorods can be assembled from solution such that each rod is Vertically Aligned and Close packed (Fig C) (-allowing the formation of a forest of nanoscale photo absorbers directly from solution). As the semiconductors are pot synthesized and processed from solution (-similar to an ink) they offer a low cost protocol to thin-film devices. The group has recently extended the nanorod synthesis and assembly protocols to copper indium gallium sulfide/selenide (CIGS) and dicopper-zinc-tin-tetrasulphide (CZTS). These materials are attractive for their high efficiencies in thin-film devices and CZTS in particular is viewed as an attractive long term solution for low cost photovoltaics as all the elements are in high natural abundance. Funding for this work is through a Science Foundation Ireland Principal Investigator Award and through the SFI Strategic Research Cluster in Solar Energy Conversion.

[2] Low cost solution synthesis of silicon and germanium nanowires by seeded and non-seeded strategies particularly  targeted towards generating wires in high yield. We have developed a novel synthetic protocol that allows the growth of group 14 nanowires in the vapor phase of high boiling point solvents in glass ware based apparatus (Fig D), allowing high purity nanowires to be formed either with or without catalysts (Fig E). Recently we have used indium and tin catalysts for form high density arrays of silicon and germanium wires on substrates and have extended the syntheses to metal silicide structures. Control over nanowire length for the formation of nanorods was achieved by a modification of this synthesis protocol (Fig F).  Investigation of nanowires of germanium as anodes for Lithium ion batteries is funded through the European Union GREENLION project with a consortium of 14 partners including large car manufactures such as SEAT and Volkswagen. The investigation of non-seeded nanowires for ICT is funded through an SFI Principal Investigator grant with industry support from Intel Ireland. For additional information see featured posts and full publication listings.