Skip to main content

Alexandre Garreau

University of Western Ontario, Chemistry, Post-Doc

Followers

11

Following

3

Co-authors

3

Public Views

2014-2016 : Postdoc, UWO, London, Ontario, Canada
2013-2014 : Postdoc, IMN, Nantes, France
2010-2013 : PhD, Université du Maine, Le Mans/Nantes, France
2009-2010 : 2 MSc projects, IMN, Nantes, France
Supervisors: Jean-Luc Duvail, Alain Bulou, and François Lagugné-Labarthet
Address: London, Ontario, Canada

less

Rennes 1

Yevgen Nazarenko

University of Cincinnati College of Medicine

Gediminas Mainelis

Désert Anthony

École Normale Supérieure de Lyon

Claude Pasquier

Toyonari Sugimoto

Interests

Uploads

Papers by Alexandre Garreau

Supporting Information : Deep Red Luminescent Hybrid coPolymer Materials With High Transition Metal Clusters Content

Electronic Supplementary Informations a) b) Figure 1s: Thermograms obtained by TGA measurements l... more Electronic Supplementary Informations a) b) Figure 1s: Thermograms obtained by TGA measurements left: % weight of sample; right: differential of weight loss of PM50 (plain line), PM10 (dashed line), PM1 (dotted line) Figure 2s: DSC thermogramms obtained for all samples, a) on heating, b) on cooling at 10 K.min-Electronic Supplementary Material (ESI) for Journal of Materials Chemistry C This journal is

Deep red luminescent hybrid copolymer materials with high transition metal cluster content

The hybrid strategy is a powerful approach to design functional materials by combining inorganic ... more The hybrid strategy is a powerful approach to design functional materials by combining inorganic dyes with an organic matrix. However, introducing high contents of inorganic species within the hybrid material is a real challenge that requires a perfect balance between the interactions of both components to avoid mainly phase segregation problems. Based on our demonstration on an anionic molybdenum cluster, we present a general method to introduce high contents of such class of nanometre sized inorganic molecular deep red dyes in a polymer matrix. Our strategy exploits the physical interactions between the organic and inorganic parts of the hybrid material and allows a high cluster rate to be introduced (up to 50 wt%) in the polymer matrix. The resulting hybrids are remarkably stable even after several months of ageing. Moreover, the Mo clusters maintain their intrinsic deep red luminescence properties while the polymer organic matrix fully maintains its processability, thanks to the di-anionic character of the Mo 6 clusters. Such materials show promising prospects in applications needing deep red emitters.

Supporting Information : Color Control in Coaxial Two-Luminophore Nanowires

by Alexandre Garreau and Yann Molard

Color Control in Coaxial Two-Luminophore Nanowires

by Alexandre Garreau, Yann Molard, and Eric Gautron

We report a general and simple approach to take control of the color of light-emitting two-lumino... more We report a general and simple approach to take control of the color of light-emitting two-luminophore hybrid nanowires (NWs). Our strategy is based on the spatial control at the nanoscale (coaxial geometry) and the spectral selection of the two kinds of luminophores in order to restrict complex charge and energy transfers. Thus it is possible to control the color of the photoluminescence (PL) as an interpolation of the CIE (Commission Internationale de l'Eclairage) coordinates of each luminophore. For this purpose, we selected a green-emitting semiconducting polymer and a red-emitting hexanuclear metal cluster compound, (n-Bu4N)2Mo6Br8F6 dispersed in a poly(methyl-methacrylate) (PMMA) matrix. The great potential and the versatility of this strategy have been demonstrated for two configurations. First, a yellow PL with a continuous change along the nanowire has been evidenced when the proportion of the PPV shell versus the nanocomposite core, that is the green:red volumic ratio, progressively shifts from 1:2 to 1:5. Second, an extremely abrupt change in the PL color with red-green-yellow segments has been achieved. A simple model corroborates the effectiveness of this strategy. PL excitation and time-resolved experiments also confirm that no significant charge and energy transfers are involved. The two-luminophore hybrid nanowires may find widespread nanophotonic applications in multicolor emitting sources, lasers and chemical and biological sensors.

Design of luminescent organic nanowires and transition-metal clusters compounds-based hybrid nanowires

Luminescent organic nanostructures are of great importance as building blocks in future miniaturi... more Luminescent organic nanostructures are of great importance as building blocks in future miniaturized photonic and optoelectronic devices because these systems rely upon the ability to tune and get new optical characteristics. One-dimensional luminescent nanostructures are new and promising systems with complex morphologies now available. In this work, we particularly investigated the control and the tuning of the emitted color of two-luminophore based nanowires. In a first part, an unfamiliar family of luminophore has been investigated: the octahedral molybdenum clusters. The vibrational modes frequencies of Mo6Br14 cluster were fully determined, as well as their photophysical properties. The unique features of these clusters were exploited into nanowires. Then, using a template method, we designed coaxial nanowires allowing the spatial separation of the two luminophores. The transition metal clusters in a PMMA matrix and PPV were selected as red and green emitters, respectively, to...

Nanofils et nanotubes de polymères : élaboration par stratégie template, propriétés, applications

Initiée au début des années 90, l’étude de nanostructures unidimensionnelles polymériques a connu... more Initiée au début des années 90, l’étude de nanostructures unidimensionnelles polymériques a connu un essor considérable au cours de la dernière décennie. Cet essor provient du développement de nombreuses stratégies de synthèse réalisé au cours des vingt dernières années, stratégies qui ont permis la maîtrise des dimensions, de la morphologie, de la composition chimique et de la pureté des phases. De plus, selon la stratégie de synthèse ou de nanostructuration adoptée, la structure moléculaire ou supramoléculaire peut s’en trouver directement affectée. Il en résulte des propriétés physiques ou physico-chimiques originales dont l’exploitation concerne des domaines d’application aussi variés que l’électronique et la photonique organique, les capteurs, la médecine, le stockage et la conversion de l’énergie. Les principales stratégies de synthèse de nanostructures unidimensionnelles organiques (nanofils - NF, nanotubes - NT, nano-rubans, nano-piliers) peuvent être classées selon qu’elles...

Facile design of red-emitting waveguides using hybrid nanocomposites made of inorganic clusters dispersed in SU8 photoresist host

by Désert Anthony, Yann Molard, and Alexandre Garreau

Integration of stable emissive entities into organic waveguide with minimum scattering is essenti... more Integration of stable emissive entities into organic waveguide with minimum scattering is essential to design efficient optically active devices. Here we present a new class of doped nanocomposite waveguides exploiting 1-nm diameter metallic cluster-based building blocks as red-NIR luminescent dyes embedded in a SU8 polymeric matrix, a reference photoresist for organic photonics. These building blocks are [Mo6Ii8(OOCC2F5)a6]2− cluster anionic units with unique chemical and physical features well suited for optical nanocomposites such as a ligand-promoted dispersibility, a large Stokes shift with a broad absorption window and an emission window in the range 600–900 nm. A whole investigation of the nanocomposite has been first performed. Optical characterizations of Cs2[Mo6Ii8(OOCCnF2n+1)a6]@SU8 nanocomposites thin film and waveguiding structures show their relevance as active layers in integrated structures with a significant increase of the refractive index of 3 × 10−2 when the cluster concentration increases up to 4 wt\%, while keeping high values for the transmitted power, as shown for different waveguide dimensions and clusters concentrations. The efficiency of photoluminescence propagation is investigated as a function of clusters concentration in the excitation area for several waveguides dimensions. Attenuation coefficient ranges between 5 and 18 dB/cm, values of the same order of magnitude as those obtained in polymeric waveguide doped with QDs or organic dyes. This original, stable and efficient nanocomposite is promising for downscaling complex nanosources and active waveguides in the visible and NIR range.

Opportunities for polymer-based nanowires in optoelectronics and nanophotonics

by Yann Molard and Alexandre Garreau

inproceedings by Alexandre Garreau

Polymer-Based Nanowires and Nanotubes: nanosources, wave-guiding

by Désert Anthony, Alexandre Garreau, and Yann Molard

One-dimensional polymer-based nano-structures such as nanowires (NWs) and nanotubes (NTs) are now... more One-dimensional polymer-based nano-structures such as nanowires (NWs) and nanotubes (NTs) are nowadays intensively investigated since they promote enhanced properties, as well as new paradigms for electronic, optical, optoelectronic, and photonic devices. Here, we propose a review of recent developments achieved in our group with collaborations on polymer based nanowires and nanotubes. Various polymer based NWs and NTs were synthesized by template strategies with advanced architectures designed for improving their functionality (waveguiding, color control of photoluminescence, photoconductivity and mechanical reinforcement,…). Both conjugated polymers (CPs) and photoresists containing photo-active species (transition metal compound clusters, single-walled-carbon nanotubes SWCNTs) were involved. The focus is made on the emerging strategies for understanding and controlling the behavior of charges, excitons and photons, as well as light propagation in sub-wavelength nanostructures.

Supporting Information : Deep Red Luminescent Hybrid coPolymer Materials With High Transition Metal Clusters Content

Electronic Supplementary Informations a) b) Figure 1s: Thermograms obtained by TGA measurements l... more Electronic Supplementary Informations a) b) Figure 1s: Thermograms obtained by TGA measurements left: % weight of sample; right: differential of weight loss of PM50 (plain line), PM10 (dashed line), PM1 (dotted line) Figure 2s: DSC thermogramms obtained for all samples, a) on heating, b) on cooling at 10 K.min-Electronic Supplementary Material (ESI) for Journal of Materials Chemistry C This journal is

Deep red luminescent hybrid copolymer materials with high transition metal cluster content

The hybrid strategy is a powerful approach to design functional materials by combining inorganic ... more The hybrid strategy is a powerful approach to design functional materials by combining inorganic dyes with an organic matrix. However, introducing high contents of inorganic species within the hybrid material is a real challenge that requires a perfect balance between the interactions of both components to avoid mainly phase segregation problems. Based on our demonstration on an anionic molybdenum cluster, we present a general method to introduce high contents of such class of nanometre sized inorganic molecular deep red dyes in a polymer matrix. Our strategy exploits the physical interactions between the organic and inorganic parts of the hybrid material and allows a high cluster rate to be introduced (up to 50 wt%) in the polymer matrix. The resulting hybrids are remarkably stable even after several months of ageing. Moreover, the Mo clusters maintain their intrinsic deep red luminescence properties while the polymer organic matrix fully maintains its processability, thanks to the di-anionic character of the Mo 6 clusters. Such materials show promising prospects in applications needing deep red emitters.

Supporting Information : Color Control in Coaxial Two-Luminophore Nanowires

by Alexandre Garreau and Yann Molard

Color Control in Coaxial Two-Luminophore Nanowires

by Alexandre Garreau, Yann Molard, and Eric Gautron

We report a general and simple approach to take control of the color of light-emitting two-lumino... more We report a general and simple approach to take control of the color of light-emitting two-luminophore hybrid nanowires (NWs). Our strategy is based on the spatial control at the nanoscale (coaxial geometry) and the spectral selection of the two kinds of luminophores in order to restrict complex charge and energy transfers. Thus it is possible to control the color of the photoluminescence (PL) as an interpolation of the CIE (Commission Internationale de l'Eclairage) coordinates of each luminophore. For this purpose, we selected a green-emitting semiconducting polymer and a red-emitting hexanuclear metal cluster compound, (n-Bu4N)2Mo6Br8F6 dispersed in a poly(methyl-methacrylate) (PMMA) matrix. The great potential and the versatility of this strategy have been demonstrated for two configurations. First, a yellow PL with a continuous change along the nanowire has been evidenced when the proportion of the PPV shell versus the nanocomposite core, that is the green:red volumic ratio, progressively shifts from 1:2 to 1:5. Second, an extremely abrupt change in the PL color with red-green-yellow segments has been achieved. A simple model corroborates the effectiveness of this strategy. PL excitation and time-resolved experiments also confirm that no significant charge and energy transfers are involved. The two-luminophore hybrid nanowires may find widespread nanophotonic applications in multicolor emitting sources, lasers and chemical and biological sensors.

Design of luminescent organic nanowires and transition-metal clusters compounds-based hybrid nanowires

Luminescent organic nanostructures are of great importance as building blocks in future miniaturi... more Luminescent organic nanostructures are of great importance as building blocks in future miniaturized photonic and optoelectronic devices because these systems rely upon the ability to tune and get new optical characteristics. One-dimensional luminescent nanostructures are new and promising systems with complex morphologies now available. In this work, we particularly investigated the control and the tuning of the emitted color of two-luminophore based nanowires. In a first part, an unfamiliar family of luminophore has been investigated: the octahedral molybdenum clusters. The vibrational modes frequencies of Mo6Br14 cluster were fully determined, as well as their photophysical properties. The unique features of these clusters were exploited into nanowires. Then, using a template method, we designed coaxial nanowires allowing the spatial separation of the two luminophores. The transition metal clusters in a PMMA matrix and PPV were selected as red and green emitters, respectively, to...

Nanofils et nanotubes de polymères : élaboration par stratégie template, propriétés, applications

Initiée au début des années 90, l’étude de nanostructures unidimensionnelles polymériques a connu... more Initiée au début des années 90, l’étude de nanostructures unidimensionnelles polymériques a connu un essor considérable au cours de la dernière décennie. Cet essor provient du développement de nombreuses stratégies de synthèse réalisé au cours des vingt dernières années, stratégies qui ont permis la maîtrise des dimensions, de la morphologie, de la composition chimique et de la pureté des phases. De plus, selon la stratégie de synthèse ou de nanostructuration adoptée, la structure moléculaire ou supramoléculaire peut s’en trouver directement affectée. Il en résulte des propriétés physiques ou physico-chimiques originales dont l’exploitation concerne des domaines d’application aussi variés que l’électronique et la photonique organique, les capteurs, la médecine, le stockage et la conversion de l’énergie. Les principales stratégies de synthèse de nanostructures unidimensionnelles organiques (nanofils - NF, nanotubes - NT, nano-rubans, nano-piliers) peuvent être classées selon qu’elles...

Facile design of red-emitting waveguides using hybrid nanocomposites made of inorganic clusters dispersed in SU8 photoresist host

by Désert Anthony, Yann Molard, and Alexandre Garreau

Integration of stable emissive entities into organic waveguide with minimum scattering is essenti... more Integration of stable emissive entities into organic waveguide with minimum scattering is essential to design efficient optically active devices. Here we present a new class of doped nanocomposite waveguides exploiting 1-nm diameter metallic cluster-based building blocks as red-NIR luminescent dyes embedded in a SU8 polymeric matrix, a reference photoresist for organic photonics. These building blocks are [Mo6Ii8(OOCC2F5)a6]2− cluster anionic units with unique chemical and physical features well suited for optical nanocomposites such as a ligand-promoted dispersibility, a large Stokes shift with a broad absorption window and an emission window in the range 600–900 nm. A whole investigation of the nanocomposite has been first performed. Optical characterizations of Cs2[Mo6Ii8(OOCCnF2n+1)a6]@SU8 nanocomposites thin film and waveguiding structures show their relevance as active layers in integrated structures with a significant increase of the refractive index of 3 × 10−2 when the cluster concentration increases up to 4 wt\%, while keeping high values for the transmitted power, as shown for different waveguide dimensions and clusters concentrations. The efficiency of photoluminescence propagation is investigated as a function of clusters concentration in the excitation area for several waveguides dimensions. Attenuation coefficient ranges between 5 and 18 dB/cm, values of the same order of magnitude as those obtained in polymeric waveguide doped with QDs or organic dyes. This original, stable and efficient nanocomposite is promising for downscaling complex nanosources and active waveguides in the visible and NIR range.

Opportunities for polymer-based nanowires in optoelectronics and nanophotonics

by Yann Molard and Alexandre Garreau

Polymer-Based Nanowires and Nanotubes: nanosources, wave-guiding

by Désert Anthony, Alexandre Garreau, and Yann Molard

One-dimensional polymer-based nano-structures such as nanowires (NWs) and nanotubes (NTs) are now... more One-dimensional polymer-based nano-structures such as nanowires (NWs) and nanotubes (NTs) are nowadays intensively investigated since they promote enhanced properties, as well as new paradigms for electronic, optical, optoelectronic, and photonic devices. Here, we propose a review of recent developments achieved in our group with collaborations on polymer based nanowires and nanotubes. Various polymer based NWs and NTs were synthesized by template strategies with advanced architectures designed for improving their functionality (waveguiding, color control of photoluminescence, photoconductivity and mechanical reinforcement,…). Both conjugated polymers (CPs) and photoresists containing photo-active species (transition metal compound clusters, single-walled-carbon nanotubes SWCNTs) were involved. The focus is made on the emerging strategies for understanding and controlling the behavior of charges, excitons and photons, as well as light propagation in sub-wavelength nanostructures.