Everything is theoretically impossible, until it is done.

• Graphic Design

  Illustrator Photoshop
• Data Science

  Python Scikit Numpy Pandas Seaborn Plotly Machine Learning Spark Deep Learning
• Python Development

  Program Flow Control Lists Tuples Dictonaries Database File Operations Object-Oriented Tkinter
• React Development

  React Redux React Native other node modules
• Web Development

  HTML5 CSS SASS Javascript Express Node.js Grunt PHP Pug JSON XML Markdown
• Chemistry

  Organic Polymer Semiconductors
• Electrical Engineering - Physics - Device Fabrication

  Transistor Phototransistor Solar Cell

• Chemical Engineering (Nanotechnology), Ph.D. | University of Waterloo

  Sep, 2013 - May, 2017

  The concept of an organic thin film transistor was first introduced in the late 1980s and research was directed toward two key merits of performance: field-effect mobility and current ON/OFF ratio. Today these two key merits of performance are still highly sought after; however, a shortcoming associated with most organic semiconductors is their susceptibility to chemical interactions and photo-excitation; to name but a few of their caveats. Consequently, the development of organic semiconductors with high charge carrier transport as well as good air stability is still desired. Nature provides a vast diversity of materials and looking for natural or nature inspired semiconductors appears to be a promising route towards interesting and pertinent materials.

  CHE745 - Topic 14: Synthetic Meth pi-conjug Poly NANO701 - Topic 3: Self-Assembly Phenomena NANO701 - Topic 11: Intro & Advanced Nanomechanics NANO702 - Topic 3: Self-Assembly Tools NANO702 - Topic 6: Microscopy ECE730 - Topic 24: Fab Nanoscale: Tech & Appls

• Molecular Science, M.Sc. | Ryerson University

  Sep, 2010 - Jun, 2013

  Both reduced zirconocene ("Cp2Zr") and zero valent lithium are known to induce coupling of alkynes to form dimers, oligmers, and polymers. Established work from Fagan et al., Tilley et al., and Eisch et al. was used as the basis for the synthesis of desired targets. First, the attempted syntheses of novel Group IV metalloles from a zirconocene intermediate were studied. There was no conclusive data to state that 2,3,4,5-tetraphenylzirconacyclopentadiene will undergo metallacycle transfer with CrCl3 and FeCl3. The presence of zirconocene dichloride suggests that metallacycle transfer may have occurred, which warrants further investigation. Monomers, 1-bromo-4-hex-1-ynyl-benzene, 1-bromo-3-(phenylethynyl)benzene, and p-dihex-1-ynylbenzene, were synthesized successfully via Sonogashira coupling. Attempts to synthesize novel monomers via lithium and "Cp2Zr" had mixed results. 1H NMR acquisition of the hydrolyzed product from zirconocene-coupling of 1-bromo-3-(phenylethynyl)benzene appeared to be successful. Lastly, lithium and "Cp2Zr" induced polymerization of novel monomers and known monomers were attempted. Metallacycle transfer from the zirconocene intermediate polymers to thiophene, thiopheneoxide, thiophenedioxide, and phosphole were attempted. However, limited characterization was completed. 1H NMR acquisitions suggest polymer by the loss of resolution and broadening of resonance signals, but further characterization via GPC is required. Monomers, and polymers were characterized using various means such as 1H, 13C, 31P, 119Sn NMR spectroscopy, UV-Vis spectroscopy, AIMS AccuTOF-DART mass spectrometry and GPC.

  MS8109 - Directed Studies Molecular Sci MS8105 - Molecular Recognition MS8108 - Adv Structure Determination CHE616 - Water and Wastewater Treatment CHE715 - Membrance Technology

• Chemistry, B.Sc. | Ryerson University

  Aug, 2005 - Jun, 2010

  This thesis reviews the steps required to work towards the synthesis of metal-containing inverse crown macrocycles based on zirconocene-coupling of diynes. Particular focus was on developing a new diyne precursor, 1,4-bis(hexynyldimethylsilyl)benzene, which could potentially promote inverse crown formation during macrocyclization of the polymer and/or during metallacycle transfers. Moreover, the new diyne offers other benefits such as increased safety, and the use of readily available and lower-cost reagents over the original diyne precursor, 1,4-bis(propynyldimethylsilyl)benzene, which Tilley et al. reported using. The newly synthesized diyne 1,4-bis(hexynyldimethylsilyl)benzene was discussed and compared to 1,4- bis(propynyldimethylsilyl)benzene. Subsequent developments were to establish a new route to new main group 13 metalloles, such as gallole and aluminole, via stannole intermediates. Work based on Eisch et al., and Fagan et al. were utilized as a basis to develop a new route to new main group 13 metalloles. Results show that the proposed route in this thesis is a potential route to developing new main group 13 metalloles. Aliquots of stannole solutions treated with either aluminum trichloride or gallium trichloride were discussed and compared.

  CKIH200 - Science Mentorship SCI180 - Orientation CPS118 - Intro Prog for Scientists EMS201 - Entrepreneurship/Innovation EMS202 - Operations Management CECN210 - Inflation/Unemployment in Can CECN505 - Issues in Cdn Labour Markets CMUS101 - Intro World/Early Euro Music CMN600 - Science, Comm and Society ECN801 - Principles of Eng Economics CHST701 - Scientific Tech/Society 20th C CHST522 - Mideast: Conf/Coop 1914-1991 SPN101 - Introduction Spanish 1 BLG143 - Biology 1 BLG144 - Biology 2 BLG311 - Cell Biology BLG402 - Limnology BLG400 - Genetics BBLG401 - Ecotoxicology CHY261 - Biochemistry CHY103 - General Chemisry 1 CHY113 - General Chemistry 2 CHY142 - Organic Chemistry 1 CHY242 - Organic Chemistry 2 CHY213 - Analytical Chemistry 1 CHY223 - Analytical Chemistry 2 CHY381 - Physical Chemistry 1 CHY382 - Physical Chemistry 2 CHY344 - Inorganic Chemistry 1 CHY449 - Inorganic Chemistry 2 CHY445 - Materials Chemistry CHY434 Analytical Chem-Complex Sample CHY330 Atomic/Molecular Spectroscopy CHY337 - Spectroscopy in Organic Chem CHY331 - Basic Chromatography CHY423 - Environmental Science CHY600 - Organic Reaction Mechanisms CHY40B - Research Project: Thesis-B MTH131 - Modern Mathematics 1 MTH231 - Modern Mathematics 2 MTH330 - Calculus and Geometry MTH380 - Probability and Statistics 1 PCS120 - Physics 1 PCS130 - Physics 2 PCS353 - Quantum Mechanics

• Computer programming and analysis, Diploma | Seneca College

  Sep, 2000 - Aug, 2004

  The Computer Programming and Analysis program provides you with a rigorous theoretical background in object-oriented methodology, particularly in program design and system analysis. Integration of web concepts and focus on the development of dynamic database-driven web applications on a variety of operating system platforms was taught.

  EAC149 - English and Communications EAC150 - College English EAC217 - The Short Story EAC397 - Business Report Writing LAN115 - Conversational Spanish for Beginners APC100 - Applied Professional Communications ICA001 - INTRODUCTION TO COMPUTERS AND APPLICATIONS ICS124 - INTRODUCTION TO COMPUTER SYSTEMS APC100 - Applied Professional Communications OPS134 - Introduction to Microcomputer Operating Systems OPS224 - Operating Systems - UNIX OPS234 - AS/400's OS/400 Midrange Operating System SYS264 - Business Systems and Analysis SYS364 - Systems Analysis and Design DBS355 - Introduction to Database DBS455 - Structured Query Language (SQL) IPC144 - Introduction to Programming Using C DBL526 - Advanced Database Concepts using Oracle OOP244 - Introduction to Object Oriented Programming SYS366 - Requirements Gathering Using OO Models INT428 - Internet Content Development and Mangement JAC444 - Introduction to Java for C++ Programmers NET605 - Security Considerations for Data Communications PRJ566 - Project Planning and Management PRO403 - Visual Basic UNX511 - UNIX Systems Programming INT422 - Internet III - Web Programming on Windows PRJ666 - Project Implementation PRO403 - Visual Basic WSA500 - Web Services Architecture

• Python Mega Course | udemy.com

  Sep, 2018 - present

  GeoJSON JSON Folium Flask

• Deep Learning | udemy.com

  Aug, 2018 - present

  The Numpy Stack in Python

• Applied Data Science with Python Specialization | coursera.org

  Aug, 2018 - present

  Introduction to Data Science in Python Applied Plotting, Charting & Data Representation in Python

• IBM Data Science Professional Certificate Specialization | coursera.org

  Aug, 2018 - present

  Python for Data Science Databases and SQL for Data Science Data Visualization with Python

• Advance CSS and Sass | udemy.com

  Jun, 2018 - present

  Flexbox CSS Grid Responsive Design

• Complete Python Masterclass | udemy.com

  Jul, 2018 - Sep, 2018

  Program Flow Control Lists Tuples Dictionaries Sets Databasing Modules Functions Generators List Comprehensions Lambda Expressions Mapping Filtering Input/Output Object-Oriented Programming

• Python for Data Science and Machine Learning | udemy.com

  Aug, 2018 - Aug, 2018

  Numpy Pandas Matplotlib Seaborn Plotly Machine Learning Linear Regression Logistic Regression K Nearest Neighbours Decision Trees and Random Forests Deep Learning Neural Nets Big Data Spark

• React: Nanodegree Program | udacity.com

  Jun, 2018 - Aug, 2018

  React Redux React Native other node modules

• Modern React with Redux | udemy.com

  Jun, 2018 - Jun, 2018

  React Redux React Router Webpack ES6

• Park and Veva Reilly | University of Waterloo

  Awarded on: Feb, 2018

  This award was established by Dr. and Mrs. Park M. Reilly to recognize skill in research as measured by analysis of an engineering problem, planning an efficient solution of the problem and achieving the solution with superior insight into the science and/or engineering involved.

• On demand Post-doctorate fellowships | FAPESP

  Awarded on: Jun, 2017

  FAPESP’s Post-Doctoral fellowship is aimed at distinguished researchers with a recent doctorate degree and a successful research track record. The fellowship enables the development of research within higher education and research institutions located in the State of São Paulo.

• Institute of Polymer Research Annual Award | Institute for Polymer Research (IPR)

  Awarded on: May, 2017

  The award is for academic excellence during a graduate student’s degree in polymer science/engineering.

• Worker-bee and Supervisor | Visions of Science

  Sep, 2010 - Sep, 2013

  Visions of Science Network for Learning Inc. (VoSNL) is a charitable organization that aims to advance the educational achievements and career aspirations of youth from low-income and marginalized communities through meaningful engagement in science, technology, engineering and mathematics (STEM) fields and research.

• A novel epoxy resin-based cathode binder for low cost, long cycling life, and high-energy lithium-sulfur battery

  Published online: Jun 28, 2018
  Journal of Materials Chemistry A 2018, 6 (29), 14315-14323

  An epoxy resin PEI–ER formed by in situ cross-linking between an epoxide compound (ER) and polyethylenimine (PEI) is developed as a new cathode binder for lithium–sulfur (Li–S) batteries. Li–S batteries using this new binder showed high initial specific capacity along with remarkable cycling stability. A composite interlayer of PEI–ER and carbon black is also developed to further enhance the cycling stability. A Li–S battery using a combination of the new binder and interlayer achieved a high initial specific capacity of 1174 mA h g−1 and an excellent capacity retention of 80% after 1000 cycles at a cycling rate of 0.5C with 70 wt% sulfur content in the cathode and an areal sulfur loading of 1.9 mg cm−2, which is among the best cycling stabilities reported for Li–S batteries to date. A Li–S battery with a high areal sulfur loading of 5.4 mg cm−2 demonstrated an initial capacity of 780 mA h g−1, which corresponds to a high areal capacity of 4.2 mA h cm−2, and an excellent capacity retention of 72% after 500 cycles.

• Effect of Acceptor Unit Length and Planarity on the Optoelectronic Properties of Isoindigo-Thiophene Donor-Acceptor Polymers

  Published online: Jun 20, 2018
  Chemistry of Materials 2018, 30 (14), 4864–4873

  Conjugated polymers with a donor–acceptor (DA) structural motif have found extensive use in a wide variety of optoelectronic devices; however, despite their ubiquity in the literature, the vast majority of these materials are simple alternating copolymers—one electron donor alternates with one electron acceptor in the polymer backbone. As a result, the impact of composition (e.g., donor/acceptor ratio) and structure (e.g., alternating, block, or random) on the optoelectronic properties of these copolymers remains poorly understood. In this work, the number of acceptor units in alternating DA copolymers is systematically increased. Two dimers of the common electron acceptor isoindigo are synthesized, one with free rotation between the subunits and one with enforced coplanarity. The two dimers are then used to synthesize donor–acceptor–acceptor (DAA) copolymers with either thiophene or terthiophene comonomers. These DAA polymers feature two electron acceptors in their repeat unit, and their optoelectronic properties are compared to those of the analogous DA polymers. It is shown that increasing the number of acceptor units causes a decrease in the LUMO energy of the resulting polymer; this effect is enhanced by enforcing coplanarity between acceptor units via ring fusion. All six polymers were tested in both organic photovoltaics (OPVs) and organic thin film transistors (OTFTs). While the DA polymers performed better in OPVs, the DAA polymers displayed more balanced charge carrier mobilities in OTFTs.

• A small bandgap (3E,7E)-3,7-bis(2-oxoindolin-3-ylidene)benzo[1,2-b:4,5-b′]difuran-2,6(3H,7H)-dione (IBDF) based polymer semiconductor for near-infrared organic phototransistors

  Published online: Nov 06, 2017
  Journal of Materials Chemistry C 2017, 5 (46), 12163-12171

  A (3E,7E)-3,7-bis(2-oxoindolin-3-ylidene)benzo[1,2-b:4,5-b′]difuran-2,6(3H,7H)-dione (IBDF)-based small bandgap donor–acceptor (D–A) polymer (PIBDFBTO-HH) was synthesized, which contains a strategically chosen solubilizing electron-rich building block, 3,3'-bis(dodecyloxy)-2,2′-bithiophene (BTO) as a donor. PIBDFBTO-HH has a very small band gap of 0.95 eV, absorbing up to 1700 nm in the near-infrared (NIR) region, which enables its application in NIR photodetection. This polymer exhibits efficient ambipolar charge transport properties with balanced hole and electron mobilities of up to 0.16 cm2 V−1 s−1 and 0.14 cm2 V−1 s−1, respectively, in organic thin film transistors (OTFTs) in the absence of light. In the p-channel operation regime, the organic phototransistor (OPT) devices based on PIBDFBTO-HH demonstrated photosensitivities (P) of 130 and 40 under the illumination of 850 nm and 940 nm LED light sources, respectively. The photoresponsivity (R) under the 940 nm LED reached 450 mA W−1. In contrast, in the n-channel operation regime, a negative photoresponse, namely a decrease in the drain current, was observed, which accounted for the increased number of trapped electrons that offset the applied gate bias.

• New Fluorinated Dithienyldiketopyrrolopyrrole Monomers and Polymers for Organic Electronics

  Published online: Sep 15, 2017
  Macromolecules 2017, 50 (18), 7080-7090

  Diketopyrrolopyrrole (DPP) derivatives are among the most efficient materials studied for both polymer solar cells (PSCs) and organic field-effect transistors (OFETs) applications. We report here the synthesis of new fluorinated dithienyldiketopyrrolopyrrole (fDT-DPP) monomers suitable for direct heteroarylation polymerization. fDT-DPP copolymers were then prepared to probe the effect of the fluorination. It was found that they feature deeper HOMO energy levels and smaller bandgaps than their non-fluorinated analogues. Moreover, some fDT-DPP copolymers show ambipolar behavior when tested in OFETs. For example, P2 shows hole mobility up to 0.8 cm2 V–1 s–1 and electron mobility up to 0.5 cm2 V–1 s–1. Inverted PSCs with power conversion efficiency (PCE) up to 7.5% were also obtained for P5. These results reported here (OFETs and PSCs) confirm that the fluorination of dithienyl-DPP moieties improves the performance of organic electronics devices. This study is also evidencing the strength of the direct heteroarylation polymerization and fDT-DPP as a new class of conjugated polymers.

• Ultrafast photoresponse organic phototransistors based on pyrimido[4,5-g]quinazoline-4,9-dione polymer

  Published online: Aug 08, 2017
  Journal of Materials Chemistry C 2017, 5 (34), 8742-8748

  We report the photoresponse characteristics of a pyrimido[4,5-g]quinazoline-4,9-dione (PQ) based polymer, PPQ2T-BT-24, which served as an active channel layer in organic phototransistors (OPTs). OPTs using this polymer showed very short rise time of 3 ms and fall time of 59 ms, photoresponsivity (R) of 0.24 and external quantum efficiency (EQE) of 50%. When PC61BM was incorporated into PPQ2T-BT-24, a significantly shortened fall time of 8 ms along with a much-improved rise time of 1 ms were realized. These response times are among the best values reported for OPTs. The R and EQE of the devices using this polymer blend also increased to 0.88 A W−1 and 189%, respectively.

• Recent progress in the development of n-type organic semiconductors for organic field effect transistors

  Published online: Aug 01, 2017
  Journal of Materials Chemistry C 2017, 5 (34), 8654-8681

  This review highlights recent major progress in the development of organic semiconductors as electron transport n-channel materials in organic field effect transistors (OFETs). Three types of materials are discussed: (1) small molecules, (2) polymers, and (3) n-doped small molecules and polymers. Much effort has been made in the modification of known building blocks, development of novel building blocks, and optimization of materials processing and device structures. These efforts have resulted in the achievement of record high electron mobilities for both small molecules (12.6 cm2 V−1 s−1) and polymers (14.9 cm2 V−1 s−1), which are approaching the highest hole mobilities achieved by p-type small molecules and polymers so far. In addition, n-doping of ambipolar and p-type organic semiconductors has proven to be an efficient approach to obtaining a greater number of n-type organic semiconductors. However, it is found that n-type organic semiconductors, in general, still lag behind p-type organic semiconductors in terms of carrier mobility and air stability. Further exploration of new building blocks for making novel materials and optimization of processing conditions and device structures are needed to improve the performance, particularly air stability.

• An aromatic amine-containing polymer as an additive to ambipolar polymer semiconductor realizing unipolar n-type charge transport

  Published online: Jul 11, 2017
  Organic Electronics 2017, 49 (October 2017), 406-414

  We report the synthesis of an aromatic amine-containing polymer (PDPAT-12) and the use of this polymer as an effective additive to an ambipolar polymer semiconductor (PIBDFBT-e37) to realize unipolar n-type charge transport in organic thin film transistors (OTFTs). With 10 wt% PDPAT-12 addition to PIBDFBT-e37, the OTFTs achieved unipolar n-type charge transport with electron mobility of up to 0.42 cm2 V−1 s−1 in nitrogen and 0.19 cm2 V−1 s−1 in air. Moreover, the polymer blend demonstrated improved stability towards ambient air (retaining 50% of its initial electron mobility after exposed in air for 28 days) than the pristine PIBDFBT-e37 (retaining 13% of its initial electron mobility under the same conditions) and the PIBDFBT-e37:PEI (polyethylenimine) blend, which lost transistor behaviour almost instantly once exposed to ambient air. Our results show that the use of this aromatic amine-containing polymer as an additive can convert an ambipolar polymer into an n-type unipolar polymer in OTFTs with much improved air stability.

• Regioisomerism of an alkyl-substituted bithiophene comonomer in (3E,8E)-3,8-bis(2-oxoindolin-3-ylidene)naphtho-[1,2-b:5,6-b′]difuran-2,7(3H,8H)-dione (INDF)-based D–A polymers for organic thin film transistors

  Published online: May 16, 2017
  Journal of Materials Chemistry C 2017, 5 (24), 5902-5909

  Two donor–acceptor (D–A) polymers based on (3E,8E)-3,8-bis(2-oxoindolin-3-ylidene)naphtha-[1,2-b:5,6-b′]difuran 2,7(3H,8H)-dione (INDF) and substituted regioisomeric bithiophene (BT) units with different side chain positions (head-to-head, HH, and tail-to-tail, TT) were synthesized. PINDFBT-(HH) achieved electron (μe) and hole (μh) mobilities as high as 0.33 cm2 V−1 s−1 and 0.15 cm2 V−1 s−1, respectively, while PINDFBT-(TT) showed an order of magnitude lower mobilities with μe of 0.07 cm2 V−1 s−1 and μh of 0.02 cm2 V−1 s−1. The distinctly different electrical performance of these two polymers originates from their different side chain placements on the bithiophene units and consequently different electronic structures, backbone coplanarity, chain packing, and thin film morphology. Our results showed that a bithiophene unit with an HH substitution pattern is much more favoured in terms of the charge transport property of the polymers.

• Direct heteroarylation polymerization: guidelines for defect-free conjugated polymers

  Published online: Mar 20, 2017
  Chemical Science 2017, 8 (5), 3913-3925

  Direct (hetero)arylation polymerization (DHAP) has emerged as a valuable and atom-economical alternative to traditional cross-coupling methods for the synthesis of low-cost and efficient conjugated polymers for organic electronics. However, when applied to the synthesis of certain (hetero)arene-based materials, a lack of C–H bond selectivity has been observed. To prevent such undesirable side-reactions, we report the design and synthesis of new, bulky, phosphine-based ligands that significantly enhance selectivity of the DHAP process for both halogenated and non-halogenated electron-rich and electron-deficient thiophene-based comonomers. To better understand the selectivity issues, density functional theory (DFT) calculations have been performed on various halogenated and non-halogenated electron-rich and electron-deficient thiophene-based comonomers. Calculations showed that the presence of bromine atoms decreases the energy of activation (Ea) of the adjacent C–H bonds, allowing undesirable β-defects for some brominated aromatic units. Both calculations and the new ligands should lead to the rational design of monomers and methods for the preparation of defect-free conjugated polymers from DHAP.

• Converting a Semiconducting Polymer from Ambipolar into n-Type Dominant by Amine End-Capping

  Published online: Jan 09, 2017
  ChemElectroChem 2017, 4 (2), 256-260

  A donor-acceptor polymer of (3E,7E)-3,7-bis(2-oxoindolin-3-ylidene)benzo[1,2-b : 4,5-b′]difuran-2,6(3H,7H)-dione (IBDF) and bithiophene (BT) exhibits typical ambipolar charge transport behaviour in organic thin film transistors. Using the electron rich triphenylamine as an end capping group, a notable suppression of hole transport is observed. This interesting phenomenon is accounted for by the hole trapping effect of the triphenylamine end-capper. Thus, this study provides a novel and facile approach to tuning the charge carrier polarity of a polymer semiconductor from ambipolar to n-type dominant.

• New 3,3'-(ethane-1,2-diylidene)bis(indolin-2-one) (EBI)-based small molecule semiconductors for organic solar cells

  Published online: May 04, 2017
  Journal of Mateials Chemistry C 2017, 5 (21), 5143-5153

  A series of new donor–acceptor–donor (D–A–D) small-molecule compounds, with 3,3′-(ethane-1,2-diylidene)bis(indolin-2-one) (EBI) as an electron acceptor building block coupled with various electron donor end-capping moieties (thiophene, bithiophene and benzofuran), were synthesized and characterized. When the fused-ring benzofuran is combined to EBI (EBI-BF), the molecules displayed a perfectly planar conformation and afforded the best charge transport properties among these EBI compounds with a hole mobility of up to 0.02 cm2 V−1 s−1. All EBI-based small molecules were used as donor material along with a PC61BM acceptor for the fabrication of solution-processed bulk-heterojunction (BHJ) solar cells. The best performing photovoltaic devices are based on the EBI derivative using the bithiophene end-capping moiety (EBI-2T) with a maximum power conversion efficiency (PCE) of 1.92%, owing to the broad absorption spectra of EBI-2T and the appropriate morphology of the BHJ. With the aim of establishing a correlation between the molecular structure and the thin film morphology, differential scanning calorimetry, atomic force microscopy and X-ray diffraction analysis were performed on neat and blend films of each material.

• A Study of the Degree of Fluorination in Regioregular Poly(3-hexylthiophene)

  Published online: Dec 27, 2016
  Macromolecules 2016, 50 (1), 162-174

  We systematically varied the degree of fluorination along the backbone of a series of highly regioregular 3-hexylthiophene-based polymers, P3HT-50F, P3HT-33F, and P3HT-25F, in which 50%, 33%, and 25% of the thiophene units within the polymer chain contain fluorine atoms in the available 4-position, respectively. These materials were homopolymerized using the Kumada catalyst transfer polycondensation method from a set of mono-fluorinated bi-, ter-, and quarterthiophenes to ensure high polymer regioregularity and evenly spaced fluorine atoms along the conjugated thiophene backbone. The monomers were obtained from a synthetic route consisting of iterative Migita–Stille couplings of fluorinated and non-fluorinated 3-hexylthiophenes. The effect of the fluorine atoms on both polymer structure and properties is presented, with supporting quantum mechanical calculations that rationalize the intrinsic conformation preferences of the three P3HT derivatives. P3HT-50F (M̅n = 34 kg/mol, 98.5% rr), P3HT-33F (M̅n = 46 kg/mol, 98% rr), and P3HT-25F (M̅n = 53 kg/mol, 95% rr) displayed HOMO levels of −5.34, −5.26, and −5.24 eV, bandgaps of 1.98, 1.98, and 1.97 eV, and average field-effect transistor hole mobilities of 4.5 × 10–3, 2.7 × 10–2, and 1.2 × 10–2 cm2 V–1 s–1, respectively.

• Thiophene-S,S-dioxidized indophenine (IDTO) based donor-acceptor polymers for n-channel organic thin film transistors

  Published online: Mar 31, 2016
  RSC Advances 2016, 6 (41), 34849-34854

  Two donor–acceptor (D–A) conjugated polymers, PIDTOBT and PIDTOBTz, based on thiophene-S,S-dioxidized indophenine (IDTO) as the acceptor building block are synthesized for solution processed organic thin-film transistors (OTFTs). The influences of the donor unit on the photophysical, electrochemical and electron-transport properties were investigated. These polymers possess very deep highest-occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels due to the strong electron accepting capability of the IDTO moiety. In OTFT devices, both polymers exhibited unipolar n-type charge transport characteristics with electron mobility up to 0.18 cm2 V−1 s−1.

• Synthesis and properties of a novel narrow band gap oligomeric diketopyrrolopyrrole-based organic semiconductor

  Published online: Apr 02, 2016
  Dyes and Pigments 2016, 131 (August 2016), 160-167

  A trimer of diketopyrrolopyrole (DPP), Tri-BTDPP, was synthesized and characterized. Tri-BTDPP has a HOMO level of −5.34 eV, a low band gap of 1.33 eV, and a hole mobility of ∼10−3 cm2 V−1 s−1 in organic field effect transistors (OFETs). Organic photovoltaic (OPV) devices using the donor/acceptor blends of Tri-BTDPP and PC71BM exhibited low power conversion efficiencies (PCE) of up to 0.72%, even though the desirable optical and electronic characteristics of this compound as a donor semiconductor for achieving high performance for OPV. Through an intensive study of the active layer using AFM, XRD, and DSC, it was found that Tri-BTDPP and PC71BM were unable to intermix and formed oversized Tri-BTDPP phases, resulting in poor charge separation. Some guidance on how to improve the OPV performance of Tri-DPP compounds is provided.

• Dramatically different charge transport properties of bisthienyl diketopyrrolopyrrole-bithiazole copolymers synthesized via two direct (hetero)arylation polymerization routes

  Published online: Jun 13, 2016
  Polymer Chemistry 2016, 7 (27), 4515-4524

  Two bisthienyl diketopyrrolopyrrole (DPP)-bithiazole based copolymers were synthesised via two different direct (hetero)arylation polymerization (DHAP) routes. When a bisthienyl DPP and 5,5′-dibromo-2,2′-bithiazole were used as monomers, the resulting polymer PA-1 showed poor solubility, ill-organized chain ordering and low performance in organic thin film transistors (OTFTs). Surprisingly, the synthetic route using a dibrominated bisthienyl DPP and 2,2′-bithiazole as monomers produced a polymer PB-1 with improved solubility, much higher crystallinity and excellent charge transport performance in OTFTs. The electron and hole mobilities of up to 0.53 cm2 V−1 s−1 and 0.06 cm2 V−1 s−1, respectively, achieved for PB-1 are more than one order of magnitude higher than those of PA-1 and also better than the mobilities reported for a similar polymer synthesized via Stille coupling polymerization. The dramatically different carrier mobilities observed for these two polymers are accounted for by their different amounts of α–β coupling linkages and branched (and lightly cross-linked) structure defects formed in the respective synthetic routes. This work also demonstrated for the first time that 2,2′-bithiazole is a suitable monomer for the construction of conjugated polymers with good electron transport performance via DHAP.

• Synthesis, characterization, and air stability study of pyrimido[4,5-g]quinazoline-4,9-dione-based polymers for organic thin film transistors

  Published online: Aug 12, 2016
  RSC Advances 2016, 6 (82), 78477-78485

  We report two novel π-conjugated polymers, PPQ2T-TVT-24 and PPQ2T-TT-24, containing the pyrimido[4,5-g]quinazoline-4,9-dione moiety and thieno[3,2-b]thiophene (TT) and (E)-1,2-bis(thiophen-2-yl)ethene (TVT), respectively, via the Stille cross-coupling reaction. Both polymers displayed good thermal stability and promising field effect transistor performance with hole mobilities of up to 3.08 × 10−3 cm2 V−1 s−1 for PPQ2T-TT-24 and 5.34 × 10−3 cm2 V−1 s−1 for PPQ2T-TVT-24. The ambient air stability of the organic thin film transistors based on these two polymers along with another previously reported PQ polymer containing bithiophene (BT) units, PPQ2T-BT-24, was studied. It was found that the moisture (H2O) in the ambient air is a detrimental component responsible for the degradation of the device performance, while oxygen, in contrast, could enhance the carrier mobility. Our study showed that the electron donor comonomer unit significantly influenced the stability of these polymers towards moisture in the stability order of TT > BT ≫ TVT. It was shown that the interaction between H2O and PPQ2T-TT-24 is physisorption and the device performance could be fully recovered, while the interaction of H2O with two other polymers involved chemical reactions, leading to permanent damages to the polymers and only partially recovered device performance upon removal of moisture.

• A fluorene-fused triphenodioxazine (FTPDO) based polymer with remarkable thermal stability and significantly enhanced charge transport performance in air

  Published online: May 12, 2016
  Dyes and Pigments 2016, 132 (September 2016), 329-335

  We report the synthesis of a novel electron acceptor building block, fluorene-fused triphenodioxazine (FTPDO), and a donor-acceptor polymer based on FTPDO and bithiophene, PFTPDOBT. This new polymer possesses a narrow band gap (1.66 eV) with low-lying frontier energy levels and exhibits hole transport characteristics in organic thin film transistors (OTFTs). Thin films of PFTPDOBT show remarkable thermal stability in air at temperatures of up to 250 °C with no noticeable differences in UV–Vis absorption characteristics in comparison to the films annealed in nitrogen. Surprisingly, OTFTs with the polymer thin films annealed in air and measured in air outperform significantly the devices annealed and measured in nitrogen.

• 3,7-Bis(( E )-2-oxoindolin-3-ylidene)-3,7-dihydrobenzo[1,2- b :4,5- b′ ]dithiophene-2,6-dione (IBDT) based polymer with balanced ambipolar charge transport performance

  Published online: May 05, 2016
  Organic Electronics 2016, 35 (August 2016), 41-46

  A novel acceptor building block, 3,7-bis((E)-2-oxoindolin-3-ylidene)-3,7-dihydrobenzo[1,2-b:4,5-b′]dithiophene-2,6-dione (IBDT), is developed to construct a donor-acceptor polymer PIBDTBT-40. This polymer has favorable highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels for balanced ambipolar charge transport. Organic thin film transistors (OTFTs) based on this polymer shows well-balanced ambipolar characteristics with electron mobility of 0.14 cm2 V−1 s−1 and hole mobility of 0.10 cm2 V−1 s−1 in bottom-gate bottom-contact devices. This polymer is a promising semiconductor for solution processable organic electronics such as CMOS-like logic circuits.

• Thiophene-S,S-dioxidized indophenines as high performance n-type organic semiconductors for thin film transistors

  Published online: Apr 28, 2016
  RSC Advances 2016, 6 (51), 45410-45418

  The synthesis of three new isomerically pure (E,E,E)-form thiophene-S,S-dioxidized indophenine (IDTO) compounds, (3Z,3′Z)-3,3′-((E)-1,1,1′,1′-tetraoxido-5H,5′H-[2,2′-bithiophenylidene]-5,5′-diylidene)bis(1-dodecyl-indolin-2-one) (4a-S1), (3Z,3′Z)-3,3′-((E)-1,1,1′,1′-tetraoxido-5H,5′H-[2,2′-bithiophenylidene]-5,5′-diylidene)bis(5-bromo-1-dodecyl-indolin-2-one) (4b-S1) and (3Z,3′Z)-3,3′-((E)-1,1,1′,1′-tetraoxido-5H,5′H-[2,2′-bithiophenyldene]-5,5′-diylidene)bis(6-bromo-1-dodecyl-indolin-2-one) (4c-S1), and their use as n-channel semiconductors for organic thin film transistors (OTFTs) are reported. Compared to the non-oxidized parent indophenine compound 3,3′-(5H,5′H-[2,2′-bithiophenylidene]-5,5′-diylidene)bis(1-dodecylindolin-2-one) (3a), 4a-S1 exhibited significantly lower HOMO and LUMO energy levels. Having bromine atoms at the 5,5′- (4b-S1) or 6,6′-positions (4c-S1), the HOMO and LUMO energy levels further decreased. In OTFT devices, these IDTO compounds exhibit unipolar n-type semiconductor behavior due to their significantly deeper LUMO and HOMO energy levels than those of 3a that shows ambipolar charge transport performance. The maximum electron mobilities of 4a-S1, 4b-S1 and 4c-S1 are in the order of 10−2 to 10−1 cm2 V−1 s−1, which are much higher than that of 3a (∼10−3 cm2 V−1 s−1), originating from the lower LUMO energy levels and the high isomeric purities of the former compounds. Among the three IDTO compounds, 4c-S1 shows the highest electron mobility of up to 0.11 cm2 V−1 s−1, which is likely due to its most extended π-electron delocalization on the LUMO wavefunction.

• Pyrazino[2,3-g]quinoxaline-2,7-dione based π-conjugated polymers with affinity towards acids and semiconductor performance in organic thin film transistors

  Published online: Feb 17, 2016
  RSC Advances 2016, 6 (26), 22043-22051

  Pyrazino[2,3-g]quinoxaline-2,7-dione (PQx) was used as a building block for π-conjugated polymer semiconductors, which demonstrated a strong acid affinity by showing marked bathochromic shifts in their absorption spectra. These polymers exhibited semiconductor performance in organic thin film transistors (OTFTs). Copolymers of PQx and bithiophene exhibited electron-dominant ambipolar transport characteristics with electron mobilities of up to 4.28 × 10−3 cm2 V−1 s−1 and hole mobilities of up to 5.22 × 10−4 cm2 V−1 s−1, while copolymers of PQx and thieno[3,2-b]thiophene exhibited hole-dominant ambipolar transport characteristics with hole mobilities of up to 4.82 × 10−2 cm2 V−1 s−1 and electron mobilities of up to 3.95 × 10−3 cm2 V−1 s−1.

• Thiophene-S,S-dioxidized Indophenine: A Quinoid-Type Building Block with High Electron Affinity for Constructing n-Type Polymer Semiconductors with Narrow Band Gaps

  Published online: Feb 02, 2016
  Angewandte Chemie International Edition English 2016, 55 (10), 3459-3462

  Three thiophene-S,S-dioxidized indophenine (IDTO) isomers, 3 a (E,E,E), 3 b (Z,E,E), and 3 c (Z,E,Z), were synthesized by oxidation of an indophenine compound. 3 b and 3 c could be converted into the most-stable 3 a by heating at 110 °C. An IDTO-containing conjugated polymer, PIDTOTT, was prepared using 3 a as a comonomer through a Stille coupling reaction, and it possesses a narrow band gap and low energy levels. In organic field effect transistors (OFETs), PIDTOTT exhibited unipolar n-type semiconductor characteristics with unexpectedly high electron mobility (up to 0.14 cm2 V−1 s−1), despite its rather disordered chain packing.

• Pyrimido[4,5-g]quinazoline-4,9-dione as a new building block for constructing polymer semiconductors with high sensitivity to acids and hole transport performance in organic thin film transistors

  Published online: Oct 26, 2015
  Journal of Materials Chemistry C 2015, 3 (45), 11937-11944

  Pyrimido[4,5-g]quinazoline-4,9-dione (PQ) was used for the first time as a building block for π-conjugated polymer semiconductors. Copolymers of PQ and bithiophene showed dramatic bathochromic shifts in their absorption spectra in the presence of protonic (acetic acid and trifluoroacetic acid) and Lewis (BBr3) acids, resulting from the strong interaction of the basic 1,6-nitrogen atoms in the PQ unit with the acid. These polymers exhibited characteristic p-type semiconductor performance with hole mobilities of up to 6.4 × 10−3 cm2 V−1 s−1 in organic thin-film transistors (OTFTs). The potential bioactivity, high sensitivity to acids, and good field effect transistor performance of these PQ-based polymers will enable their application for bio- and chemo-sensors.

• Regioisomeric control of charge transport polarity for indigo-based polymers

  Published online: Aug 18, 2015
  Polymer Chemistry 2015, 6 (39), 6998-7004

  In this work we report the opposite charge transport polarity observed for two regioisomeric polymer semiconductors. Previously, we observed n-type electron transport behaviour for a polymer semiconductor, 6,6′-PIDBDT, which contains 6,6′-indigo units. Electron distributions in the lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO) of indigo calculated by density functional theory (DFT) could explain the electron transport behaviour since electrons can be delocalized along the polymer backbone through the LUMO rather than the HOMO via the 6- and 6′-positions. Serendipitously, we found that the 5- and 5′-positions of indigo are occupied by electrons in the HOMO but empty in the LUMO, opposite to the 6- and 6′-positions. This suggests that 5,5′-PIDBDT containing the 5,5′-indigo units, a regioisomer of 6,6′-PIDBDT, may exhibit the opposite p-type charge transport behaviour. To prove our assumption, we synthesized 5,5′-PIDBDT and found that this polymer indeed showed p-type semiconductor behaviour. Hence we demonstrated a novel approach to control the electron or hole charge transport polarity by simply varying the main chain regiochemical connections.

• Branched alkyl ester side chains rendering large polycyclic (3E,7E)-3,7-bis(2-oxoindolin-3-ylidene)benzo[1,2-b:4,5-b′]difuran-2,6(3H,7H)-dione (IBDF) based donor–acceptor polymers solution-processability for organic thin film transistors

  Published online: Aug 04, 2015
  Polymer Chemistry 2015, 6 (37), 6689-6697

  We report the development and use of a new type of branched alkyl ester side chain for donor–acceptor polymers. The synthesis of the branched alkyl ester side chain precursors is simple and the side chain's branching position and branch length can be adjusted conveniently by choosing the readily available starting materials. (3E,7E)-3,7-bis(2-oxoindolin-3-ylidene)benzo[1,2-b:4,5-b′]difuran-2,6(3H,7H)-dione (IBDF) based donor–acceptor polymers were previously found to have poor solubility in common organic solvents. Herein, we used this new type of branched alkyl ester side chain for the copolymers of IBDF and bithiophene and explored how the branch length would impact the microstructure and charge transport properties of these polymers. With an optimal branch length, the polymer demonstrated ambipolar charge transporting characteristics with a high electron mobility of up to 0.35 cm2 V−1 s−1 and a hole mobility of up to 0.20 cm2 V−1 s−1 in organic thin film transistors (OTFTs), which is comparable to the one with branched alkyl side chains.

• (3E,8E)-3,8-Bis(2-oxoindolin-3-ylidene)naphtho-[1,2-b:5,6-b']difuran-2,7(3H,8H)-d ione (INDF) based polymers for organic thin-film transistors with highly balanced ambipolar charge transport characteristics

  Published online: Jul 16, 2015
  Chemical Communications 2015, 51 (70), 13515-13518

  Two donor–acceptor (D–A) conjugated polymers, PINDFTT and PINDFBT, based on a novel electron acceptor, (3E,8E)-3,8-bis(2-oxoindolin-3-ylidene)naphtho-[1,2-b:5,6-b′]difuran-2,7(3H,8H)-dione (INDF), are synthesized for solution processed organic thin-film transistors. Both polymers exhibited highly balanced ambipolar characteristics with hole and electron mobilities up to 0.51 cm2 V−1 s−1 and 0.50 cm2 V−1 s−1, respectively.

• Surface modification of polydimethylsiloxane elastomer for stable hydrophilicity, optical transparency and film lubrication

  Published online: May 28, 2015
  Colloids and Surfaces A: Physicochemical and Engineering Aspects 2015, 482 (5 October 2015), 267-275

  The surface of polydimethylsiloxane (PDMS) elastomer was hydrophilized by poly(acrylic acid) (PAAc) using Surface Initiated Atomic Transfer Radical Polymerization (Si-ATRP). The ATRP initiator chosen was ((Chloromethyl) phenylethyl) trichlorosilane, which was immobilized on the surface of the PDMS through a simple but innovative method of drop coating, in contrast to the commonly used vapor deposition and solution-immersion methods. Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) and X-ray Photoelectron Spectroscopy (XPS) were employed to examine surface properties of modified PDMS and confirmed presence of the PAAc chains covalently bonded to the PDMS surface. Physical properties and topography of the modified sample were characterized by water contact angle measurement and Atomic Force Microscopy. It is shown that the drop-coating of the silane initiator for ATRP modification with PAAc can result in good surface hydrophilization while causing minimum damage to the PDMS preserving its desired optical transparency. The resultant hydrophilic PDMS is stable in air and has film lubrication behavior in aqueous conditions and may be used in the development of advanced microfluidic devices and sensors where both surface hydrophilicity and bulk transparency are desired.

• An indigo-based polymer bearing thermocleavable side chains for n-type organic thin film transistors

  Published online: Apr 15, 2015
  Journal of Materials Chemistry C 2015, 3 (20), 5226-5232

  A new n-type semiconducting polymer based on indigo having thermocleavable tert-butoxycarbonyl (t-Boc) groups was synthesized and used as an active layer in organic thin film transistors (OTFTs). Twisting of the polymer main chain due to the presence of the bulky t-Boc groups renders this indigo-based polymer highly soluble. A post-deposition thermal treatment at a temperature above 170 °C could remove the t-Boc groups to retrieve the highly coplanar geometry of the unsubstituted indigo units. The thermally annealed polymer semiconductor films at 200 °C showed an electron mobility of up to ∼6 × 10−3 cm2 V−1 s−1 in OTFTs, which is a 5-fold increase compared to that of the indigo-based polymers reported previously due to the retrieved high backbone coplanarity.

• (3E,7E)-3,7-Bis(2-oxoindolin-3-ylidene)-5,7-dihydropyrrolo[2,3-f]indole-2,6(1H,3H )-dione based polymers for ambipolar organic thin film transistors

  Published online: Apr 06, 2015
  Chemical Communications 2015, 51 (38), 8093-8096

  A novel acceptor, (3E,7E)-3,7-bis(2-oxoindolin-3-ylidene)-5,7-dihydropyrrolo[2,3-f]indole-2,6(1H,3H)-dione, was reported. Donor–acceptor (D–A) polymer semiconductors using this new building block showed high ambipolar charge transport performance with hole and electron mobilities up to 0.19 and 0.09 cm2 V−1 s−1, respectively, in thin film transistors.

• New synthetic route to pyrimido[4,5-g]quinazoline-4,9-diones

  Published online: Mar 21, 2015
  Tetrahedron Letters 2015, 56 (17, 22 April 2015), 2280-2282

  A facile and moderate to high yielding protocol is reported for the synthesis of 2,7-bis(5-bromothiophen-2-yl)-3,8-bis(2-decyltetradecyl)-3,8-dihydropyrimido[4,5-g]quinazoline-4,9-dione, which can be potentially used to synthesize other pyrimido[4,5-g]quinazoline-4,9-diones. Moreover, new pyrimido[4,5-g]quinazoline-4,9-diones synthesized by this route can potentially be used as organic semiconductors.

• Synthesis and properties of indigo based donor-acceptor conjugated polymers

  Published online: Mar 04, 2014
  Journal of Materials Chemistry C 2014, 2 (21), 4289-4296

  Indigo is for the first time used as a building block to construct polymer semiconductors for organic thin film transistors (OTFTs). Two donor–acceptor polymers using indigo as the acceptor and bithiophene as the donor are synthesized via Stille coupling polymerization. Two types of acyl groups, 2-hexldecanoyl (for polymer P1) and 2-octyldodecanoyl (for polymer P2), are utilized as solubilizing side chains. These polymers possess very deep highest-occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels, due to the strong electron accepting capability of the indigo moiety. In OTFT devices, characteristic n-type semiconductor performance with electron mobility of up to ∼10−3 cm2 V−1 s−1 is observed.

• Oral Presentation | Novel organic semiconductors and their evaluation in organic thin film transistors and phototransistors, Lorena, Brazil

  Nov, 2017

  Invited Talk, Universidade de São Paulo, A Escola de Engenharia de Lorena

• Oral Presentation | Novel robust organic semiconductors for organic thin film transistors, Gramado, Brazil

  Sep, 2017

  SBPMat XVI - MRS Meeting

• Oral Presentation | Unipolarization of ambipolar organic thin film transistors, Gramado, Brazil

  Sep, 2017

  SBPMat XVI - MRS Meeting

• Oral Presentation | Novel semiconductive materials for organic thin film transistors, São Carlos, Brazil

  Jun, 2017

  Invited Talk, Universidade de São Paulo, Instituto de Física de São Carlos

• Oral Presentation | Nature-inspired polymers: promising materials for organic thin film transistor-based sensors, Waterloo, Canada

  Nov, 2017

  Institute of Polymer Research (IPR) 2017

• Oral Presentation | Novel semiconductive materials for organic thin film transistors, Campinas, Brazil

  Dec, 2016

  Laboratório Nacional de Nanotecnologia (LNNano)

• Poster Presentation | Air stability study of novel pyrimido[4,5-g]quinazoline-4,9-dione-based polymers for organic thin film transistors, Guelph, Canada

  Nov, 2016

  Nano Ontario Conference

• Oral Presentation and Poster Presentation | The synthesis and properties of pyrazino[2,3-g]quinoxaline-2,7-dione and pyrimido[4,5-g]quinazoline-4,9-dione based conjugated polymers and application in organic thin film transistors, Waterloo, Canada

  May, 2016

  Institute of Polymer Research (IPR) 2016

• Poster Presentation | Synthesis and properties of pyrimido[4,5-g]quinazoline-4,9-dione based π-conjugated polymers, Waterloo, Canada

  Mar, 2016

  WINGSS/MNS Nanotechnology Poster Session

• Poster Presentation | Pyrimido[4,5-g]quinazoline-4,9-dione as a novel building block for channel semiconductors in organic thin film transistors, Waterloo, Canada

  Nov, 2015

  Waterloo Undergraduate Nanotechnology Conference

• Poster Presentation | Synthesis and properties of pyrimido[4,5-g]quinazoline-4,9-dione based π-conjugated polymers, Ottawa, Canada

  Jun, 2015

  98th Canadian Chemistry Conference and Exhibition

• Poster Presentation | Towards the synthesis of inverse crown metal containing macrocycles based on zirconocene coupling of diynes, Toronto, Canada

  Jun, 2010

  93rd Canadian Chemistry Conference and Exhibition

• Poster Presentation | Synthesis of poly(oxothiazenes) via the polycondensation of n-silylsulfonimidoyl chlorides, Hamilton, Canada

  May, 2010

  92nd Canadian Chemistry Conference and Exhibition