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Organic & Organometallic Optoelectronic Materials

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Research
Researcher ID : J-6102-2012 Scopus Author ID : 6506216664


Members of the Zysman-Colman group conduct research at the interface of organometallic, optoelectronic materials, physical organic, and supramolecular chemistry. We use a combination of organic synthesis, coordinational chemistry, varied analytical techniques such as NMR, mass spectrometry, fluorimetry, and cylic voltammetry, coupled with molecular modeling to address three major research goals relating to energy conversion:
  • Development of improved luminophores for visual displays and flat panel lighting based on organic light emitting diode (OLED) and light-emitting electrochemical cell (LEEC) architectures;
  • Design of more efficient dyes for Grštzel-type dye-sensitized solar cells (DSSCs);
  • On a more fundamental level, investigation of what properties within an emissive molecule renders it a good photosensitizer capable of promoting electrocyclic and radical reactions using visible light.
Research Overview: Research Overview Poster - 2014
Luminophores

The invention of artificial lighting, dating from Thomas Edisonís invention of the incandescent light bulb in 1879, is arguably one of the most important inventions of humankind. Artificial lighting permits most human activities to continue past sundown, thus immeasurably increasing worldwide human productivity. Though Edisonís device was much brighter than candle lighting, it was inefficient, converting only 0.2% of electricity into light. Since this seminal invention, many other lighting devices has been developed, from the tungsten lamp, to fluorescent tubes to halogen lighting to light-emitting diodes (LEDs) to organic light-emitting diodes (OLEDs). With each further iteration in lighting technology, the quality (pureness of colour), power efficiency and brightness of the light produced by the device have each improved.

Producing devices that are energy efficient is of particular importance as, according to the US department of Energy, it is estimated that 1/3 of commercial electricity use and 10% of household electricity consumption in the United States alone is dedicated towards artificial lighting. Artificial lighting represents a $15 Billion market in the United States alone and almost $91 Billion worldwide, corresponding to 20% of total worldwide energy output. The environmental impact related to this energy consumption is enormous and is estimated to be responsible for 7% of global CO2 emissions.

Whereas inorganic LED and organic or polymer OLED lighting is now the state of the art in artificial lighting, their high cost and small active surface area are still barriers to wide adoption. In fact, for large surface area outdoor lighting applications, low-pressure sodium lamps are still the technology of first choice. Within this context, there is an urgent need to find alternative artificial lighting technologies that are of lower production cost, more energy efficient, colour tunable and can be used in environments not currently accessible to current LED and OLED technologies. It is implicit that in a similar manner to OLEDs, such a new lighting technology would have applications in visual displays, telecommunication and sensors.

We are actively involved in improved luminophore design, particularly with respect to Ir and Pt complexes, with the goal of addressing the current challenges in solid state lighting and visual displays.

Solar Generated Electricity

In light of dwindling fossil fuel resources and the trmendous environmental impact of their extraction and use, humanity must find alternative sources of energy. An obvious source originates from the sun, which produces an enormous amount of energy annually (3 X 1024 J/year). In order to meet our current energy needs, we require only that solar paneling cover 0.1% of the Earthís surface and that each solar panel possesses a 10% conversion efficiency. A particularly promissing technology is the dye-sensitized solar cell (DSSC). The DSSC functions through an electron transfer process between a seminconductor and an adsorbed photo-excited dye. The now-oxidized dye is then reduced by a secondary redox couple, which itself is regenerated at the cathode by electrons completing the circuit via an external load. After more than 20 years of concerted research, proven efficiencies for (DSSCs) have only recently bypassed the 13% mark. Nevertheless, design challenges relating to cost, stability and conversion efficiency have yet to be entirely overcome for this technology to become widely commercially viable.

Our research in this area is directed to the discovery of new organometallic molecules that are cheaper to synthesize, can act as more efficient captors of solar energy that will directly lead to more efficient solar cells and are more stable than the current Ru and metal porphyrin state-of-the-art dyes.
Photoredox Catalysis

Recently, several groups have developed "green" synthetic methodologies employing luminescent materials, mostly based on Ru and Ir complexes, as photosensitizers (also known as photoredox catalysts). What is ill understood is what makes a good photoredox catalyst for any particular organic transformation and what lessons learned can be transferable from one reaction to another.

We will address these questions through a series of concerted structure-property investigations in concert with a materials informatics approach. We are also interested in exploiting photoredox catalysis towards the synthesis of organic materials directed towardss energy storage/conversion properties.
 
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