Lessard Research Group - Next Generation Materials for Next Generation Applications


About Prof. Benoit Lessard    |    Group Members 


Prof. Lessard on “5 min of science” 2017

The demand for high performance materials with complex functionality is perpetual due to the nature of modern technologies. These materials must also be ideally environmentally benign, inexpensive and easily fabricated to displace current industrial materials or to create new applications that benefit society. Polymers have long been desirable due to their mechanical flexibility and their relatively low fabrication cost. To significantly modify the microstructure and the desired performance of the final polymer, substitution of the constituent monomer used or the addition of a second or even third monomer into the mixture can easily be accomplished. Polymers with functional groups either randomly distributed or as distinct blocks have found application in next-generation separation media, flexible solar cells, biocompatible polymers for biosensors, catalyst supports and nano-reactors to name but a few.

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Research Topics

Phthalocyanines Design for OTFTs and OPVs


Organic electronics utilize carbon based semiconductors in place of the conventional inorganic semiconductor. The same characteristics which make dyes and pigments colourful and photo luminescent also make them desirable as organic semiconductors. Therefore the use of commercial dyes and pigments as starting materials is ideal due to their wide availability and low manufacturing cost. Through organic chemistry we can tune the molecule solubility, its solid state arrangement and its photo physical properties, therefore, improving their performance in organic electronic devices. Phthalocyanines, for example, are commercial dyes used as a pigment, colourant and even xerographic material. We have several ongoing projects which utilize silicon phthalocyanines as active materials in organic photovoltaics (OPVs) and organic think film transistors (OTFTs).

Recent publications on this topic:

Melville, O. A.; Grant, T. M.; Lessard, B. H.* Silicon Phthalocyanines as N-Type Semiconductors in Organic Thin Film Transistors. J. Mater. Chem. C, 2018, 6,5482-5488. doi: 10.1039/C8TC01116H

Grant, T. M.; Gorisse, T., Dautel, O.; Wantz, G.*; Lessard, B. H.* Multifunctional silicon phthalocyanine ternary additive in bulk heterojunction OPV: increased device performance and stability. J. Mater. Chem. A., 2017, 5, 1581-1587, doi: 10.1039/C6TA08593H

OTFTs : Sensors and Stability


With the increasing demand for flexible, inexpensive technology, it is believed that the demand for organic circuitry will exceed that of silicon electronics. In organic devices, thin film transistors (OTFT), and photovoltaic cells (OPVs), the processes of charge charge transport, and charge interaction with electrodes is crucial. Environmental conditions such as temperature and the prescence of moisture and oxygen can have a significant effect on device performance. In most of these cases, these phenomena are experienced within a material on the nanoscale and at the interface between two organic layers, organic and metal or organic and inorganic interface. Therefore the study of device stability, effect of environment on performance and surface chemistry is crucial. Finally these interactions can be utilized to develop sensors: as the analyte of interest interacts with the semiconductor we can measure a unique electrical response.

Recent publications on this topic:

Brixi, S.; Melville, O. A.; Boileau, N. Lessard, B. H.* The Influence of Oxygen and Temperature on the Performance of PBDB-T and P3HT in Organic Thin Film Transistors. J. Mater. Chem. C, 2018, 6, 11972-11979  doi:10.1039/C8TC00734A

Rice, N. A.; Bodnaryk, W.; Mirka, B.; Melville, O.; Adronov, A.*; Lessard, B. H.* Polycarbazole-Sorted Semiconducting Single Walled Carbon Nanotubes for Incorporation Into Organic Thin Film Transistors. Adv. Elec. Mater., 2019, 5, 1, 1800539. doi: 10.1002/aelm.201800539

Boileau, N. T.; Melville , O.; Mirka, B.; Cranston, R.; Lessard, B. H.* P and N type copper phthalocyanines as effective semiconductors in organic thin- lm transistor based DNA biosensors at elevated temperature. RSC Advances, 2019, 9, 2133-2142. doi: 10.1039/C8RA08829B

Nitroxide-mediated polymerization (NMP)

Over the last 15-20 years the interest in reversible-deactivation radical polymerization (RDRP) more commonly known as controlled radical polymerization (CRP) has vastly expanded due to its ability to produce highly defined polymers on a molecular level, which rival those produced by traditional, and more stringent, living techniques such as ionic polymerization. Nitroxide-mediated polymerization (NMP), a type of CRP, has realistic scale-up potential and can be used to produce highly defined polymers without the need of air-free transfers, transition metal catalysts or problematic thiol agents. Therefore, no additional purification of the final polymer is necessary prior to being used for sensitive electronic or biological applications. Our research focuses on using NMP for the synthesis of model functional materials with controlled microstructure for numerous applications such as  organic electronic applications.

Recent publications on this topic:

Peltekoff, A. J.; Therrien, I.; Lessard, B. H.*; Nitroxide Mediated Polymerization of 1-(4-vinylbenzyl)-3-butylimidazolium ionic liquid containing homopolymers and methyl methacrylate copolymers. Can. J. Chem. Eng., 2019, 97, 1, 5-16. doi: 10.1002/cjce.23348

King, B.; Lessard, B. H.* Controlled Synthesis and Degradation of Poly(N-(Isobutoxymethyl) Acrylamide) Homopolymers and Block Copolymers. Macromol. React. Eng. 2017 11, 2, 1600073 (1-10). (Advanced Science News, Cover Articledoi: 10.1002/mren.201600073

Melville, O.; Imperiale, C.; King, B.; Lessard, B. H.* Orthogonally Processable Carbazole-Based Polymer Thin Films by Nitroxide-Mediated Polymerization. Langmuir bf 2016, 32, 13640-13648. doi:10.1021/acs.langmuir.6b0392