Energy et environment

+efficient +profitable +ecological

Solar energy is one of the most promising alternatives to fossil fuels. The challenge, however, lies in developing cells whose performance is sufficient to make this solution economically viable. One promising strategy – the Grätzel cell – involves the generation of a current following the stimulation of a dye adsorbed on TiO₂ nanoparticles, into which electrons are injected and transferred to an exterior circuit. This elegant strategy must undergo modifications in terms of materials used, in order to make the Grätzel cell more attractive, notably when targeted applications require the production of cells with a large surface area. For example:

1. The electrolyte used is based on I- and I₃- ions, whose mix, in large concentrations, is colourful and corrosive to the cathodic material as well as the silver-based electrical contacts;
2. The cathodic catalyst is based on platinum, an expensive material.

Prof. Marsan’s team developed an effective, transparent and non-corrosive organic electrolyte. Furthermore, the platinum electrode was replaced by a less expensive, more stable high-performance material: cobalt sulfide.   

Given its tremendous potential, this was recognized as one of the 10 most important discoveries of 2010 in Quebec, and published in the prestigious magazine Nature Chemistry.

Reference

[1] M. Wang, N. Chamberland, L. Breau, J.-E. Moser, R. Humphry-Baker, B. Marsan, S. M. Zakeeruddin, M. Grätzel, Nature Chemistry, 2, 385-389 (2010)

Researcher

Pof. B. Marsan and Prof L. Breau (UQAM)

IRDQ contribution

• Electrochemical characterization
• Liquid phase chromatography
• Nuclear magnetic resonance (NMR)

+ecological  +performance

In collaboration with Professor Christian Pellerin, Professor Marcotte’s team developed products based on protein extracted from the anchoring filaments or byssus of blue mussels. The first researchers to develop this type of biomaterial, they succeeded in putting the byssus filaments into a solution and forming films whose mechanical properties depend on the pH.

This work opened the way for the development of materials that could be commercialized. These materials could be applied, for example, to the engineering of soft tissues such as tendons or the delivery of medication. In addition, by enhancing fibres considered to be aquaculture waste, these materials could have a significant socio-economic impact on coastal regions as well as positive repercussions for the environment.

References

[1] F Byette, C Pellerin, I Marcotte, J. Mater. Chem. B 2, 6378 – 6386, 2014

Researchers

Pr. Marcotte (UQAM) and Pr. Pellerin (Université de Montréal)

+small +structured +efficient

In recent years, phosphor-free III-nitride nanowire light-emitting diodes (LEDs) have been intensively studied as a promising candidate for future solid-state lighting and full-color display applications. Compared with the conventional quantum well based LEDs, nanowire devices offer several potential advantages, including drastically reduced dislocations and polarization fields, flexible emission wavelength tenability and negligible efficiency droop at high injection current. To date, however, such nanowire devices generally exhibit very low output power.

Professor Mi and his team have shown that the underlying cause for the low output power of nanowire LEDs is directly related to the poor carrier injection efficiency, due to the surface recombination. His team further developed phosphor-free InGaN/GaN/AlGaN dot-in-a-wire core-shell white LEDs grown by molecular beam epitaxy on Si substrate, which can break the carrier injection efficiency bottleneck, leading to a massive enhancement in the output power. At room-temperature, the devices can exhibit an output power of ∼1.5 mW, which is more than 2 orders of magnitude stronger than nanowire LEDs without shell coverage. Additionally, such phosphor-free nanowire white LEDs can deliver an unprecedentedly high color rendering index of ∼92−98 in both the warm and cool white regions, with the color rendering capability approaching that of an ideal light source, i.e. a blackbody.

References

[1] Hieu Pham Trung Nguyen , Shaofei Zhang , Ashfiqua T. Connie , Md Golam Kibria , Qi Wang , Ishiang Shih , and Zetian Mi, Nano Letter, 13 (11), 5437-5442 (2013)

Researchers

Prof. Zetian Mi (McGill University)

IRDQ contribution

• Transmission electron microscopy (TEM)

+profitable +efficient +ecological

Molecular semiconductors are revolutionizing technology and replacing classical hard materials now used in devices such as solar cells. Québec includes international leaders in molecular electronics. The Perepichka group has correlated bulk electrical properties (such as charge mobility) with underlying molecular structure and packing in the solid state. This has led to the development of semiconductors with record-breaking performance in light-effect transistors, and the group has taken this approach further by demonstrating a crystal-engineering route to molecular materials for use in solar cells. The Hanan and Skene groups have an industrial collaboration with St-Jean Photochimie to discover innovative dyes for use in solar cells. Solar cells and other devices based on thin layers of molecular materials have attractive features, including flexibility and inexpensive large-scale fabrication, but their efficiency remains low. A primary goal of the Wuest group is to learn how to optimize the nanoscale organization of the molecular components and ensure that the structure remains essentially unchanged during operation of the device. Making progress in this area requires strong skills in molecular design and synthesis, combined with a deep understanding of molecular interactions.

Researchers

Prof. Dmitrii F. Perepichka (McGill University), Prof. Garry S. Hanan (Université de Montréal), Prof. William Skene (Université de Montréal), and Prof. James D. Wuest (Université de Montréal)

Company

Xerox, Solaris Chem, St-Jean Photochimie

IRDQ contribution

• Xray diffraction (XRD)