Yuning Li

University of Waterloo | UWaterloo · Department of Chemical Engineering

Biomaterials‐based electronic devices (BEDs) have remarkable advantages such as biocompatibility and biodegradability, which are expected to have promising prospects in the development of green electronics such as wearable smart sensors and brain‐like synaptic devices. However, the development of BEDs is still in its infancy, and much work remains...

Previously, we developed several carbamate side chain-substituted hemi-isoindigo (HID)-based conjugated polymers, which demonstrated excellent sensitivity and stability as the sensing layers in chemiresistive temperature sensors. This work investigated the effects of the side chains on the HID units by changing the carbamate to alkyl side chains. S...

We report the first use of lithiated carboxylated nitrile butadiene rubber (XNBR-Li) as a functional binder for the sulfur cathode of lithium sulfur batteries (LSBs). XNBR-Li has strong adhesion to sulfur and carbon black particles, forming a uniformly dispersed and robust sulfur cathode structure. Furthermore, due to the presence of the -COOLi gro...

For organic memristors, non-zero-crossing current-voltage (I-V) curves are often observed, which can be attributed to capacitive effects. If the conversion between the capacitance-dominated state (CDS) and the memristance-dominated state (MDS) can be realized in a controllable manner, more device functions can be obtained. In this work, a two-termi...

A series of donor-acceptor polymers, namely PTEB, PMEB, PEEB, and PPEB, are designed and synthesized for temperature sensing. The polymers are composed of hemi-isoindigo as the acceptor unit, 3,3″-bis(dodecyloxy)-2,2″-bithiophene as the donor unit, and thiophene as the spacer unit. Carbamate solubilizing side chains are used to increase the solubil...

There is still a considerable gap between the actual and theoretical capacities of the commercial cathode material LiFePO4 (LFP) for lithium-ion batteries (LIBs). Here, a new strategy to release the full capacity of LFP through the rocking-chair coordination chemistry is reported. Specifically, the zinc acetate-diethanolamine complex (Zn(OAc)2·DEA)...

The rapid growth of wearable electronics, Internet of Things, smart packaging, and advanced healthcare technologies demand a large number of flexible, thin, lightweight, and ultralow-cost sensors. The accurate and precise determination of temperature in a narrow range (~0–50 °C) around ambient temperatures and near-body temperatures is critical for...

This study reports the development of a new type of MOFs by inserting transition metals into the bipyridine dicarboxylate ligand-containing Zr-based MOF, UiO-67-bpy, through one-pot synthesis (OPS) and post-synthesis functionalization (PSF) methods. Transition metals including Ni, Co, Mn, Fe and Cu were inserted into MOF to create open metal site (...

Two new π-conjugated polymers with donor backbone and π-conjugated indolin-2-one side chains, PBDTTI and PBDTTIF, are designed and synthesized as wide bandgap donors for non-fullerene acceptor-based organic solar cells (OSCs). The monomers containing electron accepting indolin-2-one side chains, (Z)-3-((2,5-dibromothiophen-3-yl) methylene)-1-methyl...

Eliminating interfacial incompatibility and creating smooth ions/electrons transport at the interfaces of cathode│electrolyte│anode, are keys for the practical application of all-solid-state lithium-sulfur battery (ASSLSB). Here, we report a fully integrated-ASSLSB (i-ASSLSB) whose interfacial resistances are suppressed by the segmental motion of p...

Despite silicon being a promising candidate for next-generation lithium-ion battery anodes, self-pulverization and the formation of an unstable solid electrolyte interface, caused by the large volume expansion during lithiation/delithiation, have slowed its commercialization. In this work, we expand on a controllable approach to wrap silicon nanopa...

This study reports the development of a new type of Zr-based MOF by inserting copper and carboxylate into HCl modulated UiO-67 (UiO-67-vac) which gained higher surface area/vacant than UiO-67. Copper was inserted into MOF containing uncoordinated carboxylate group, to create open metal site in the form of 􀀀 COOCu which called UiO-67-ox-Cu. PXRD, FT...

Polymer‐based solid electrolytes (PSEs) have attracted tremendous interests for the next‐generation lithium batteries in terms of high safety and energy density along with good flexibility. Remarkable performances have been demonstrated in PSEs, which endowed PSEs with the potential to replace liquid electrolytes to meet the market demands. In this...

Lithium-sulfur (Li-S) battery is a promising high-density energy storage technology. Using conductive polymers to enhance the performance of Li-S battery has received much attention. In this work, a convenient and low-cost in-cell electropolymerization method is developed for preparation of a conductive polymer, poly(3,4-ethylenedioxythiophene) (PE...

A novel donor–acceptor (D‐A) conjugated polymer, poly[bis(2‐ethylhexyl)3‐(3′′,4′‐bis(dodecyloxy)‐[2,2′:5′,2′′‐terthiophen]‐5‐yl)‐1,4‐dioxo‐6‐(thiophen‐2‐yl)pyrrolo[3,4‐c]pyrrole‐2,5(1H,4H)‐dicarboxylate] (PDEB), comprising an electron‐accepting carbamate side‐chain bearing thiophene‐flanked diketopyrrolopyrrole (DPPTh) and an electron‐donating 3,3′...

In the past few years, the power conversion efficiency (PCE) of organic solar cells (OSCs) has improved rapidly with the milestone value exceeding 18%, primarily owing to the development of novel non-fullerene acceptors (NFAs) as well as the matching polymer donors. The molecular structure of a polymer donor fundamentally determines its molecular p...

The “shuttle effect” of soluble lithium polysulfides (LPS), which causes rapid capacity fading, remains a lingering issue for lithium-sulfur batteries (LSBs). Herein, we report a new type of reactive molecule-based (or molecular) LPS trapper, zinc acetate-diethanolamine (Zn(OAc) 2 ·DEA), which demonstrated a molecular efficiency of 1.8 for LPS trap...

Electron-withdrawing alkyloxime was, for the first time, used as a novel side chain for conjugated polymers. Two polythiophenes, PTOBT-Z with the Z-isomer alkyloxime side chains and PTOBT-Z/E with a mixture of Z- and E-isomer alkyloxime side chains, were synthesized. They possess deep highest occupied molecular orbital energies (EHOMO’s) down to -5...

Ultrasmall particle size (<10 nm) and rich oxygen vacancies are two sought‐after characteristics for titanium dioxide (TiO2) to achieve high performance, namely, high rate and high storage capacity, when being used as an anode in lithium‐ion batteries (LIBs). However, free TiO2 particles simultaneously possessing both characteristics have not been...

Charge transport in conjugated polymer depends critically on the chemical structure of the polymer chain, morphology, aggrega-tion and the complex microstructure in solid state. Recently, molecular planarity and intramolecular electron transport were asso-ciated with J-type aggregation, while coplanar stacking and intermolecular hole transport were...

The development of design strategies in both ambipolar and electron conducting OTFT materials is important for producing high performance materials and devices in organic electronics. Isoindigo donor-acceptor polymers have been well studied as hole-conducting materials in OTFTs, while more electron-deficient, acceptor-rich isoindigo polymers have b...

Diketopyrrolopyrrole-based (DPP-based) polymers are a very important class of materials for both organic solar cells (OSCs) and organic field-effect transistors (OFETs). Here we report an optimised synthesis of fluorinated dithienyl-diketopyrrolopyrrole (fDT-DPP) and three new highly fluorinated fDT-DPP-based materials obtained from direct heteroar...

Here, we first propose a comprehensive evaluation method of lithium sulfur (Li-S) pouch cells safety performance, including nail penetration, impact, external short circuit and overcharge tests. Using high definition IR imaging combined with a temperature-voltage data acquisition system, XPS and SEM, careful analysis of the thermal and electrochemi...

We report the design, synthesis, and properties of a novel type of donor (D)‐acceptor (A) polymer, PTIBT, with a donor backbone and acceptor side chains (Type II D‐A polymer) as donor for organic solar cells (OSCs) as opposed to the conventional D‐A polymers having both donor and acceptor units on backbone (Type I D‐A polymers). PTIBT having a back...

A new azine polymer poly(4,4′-didodecyl-2,2′-bithiophene-azine) (PDDBTA) was synthesized in only three steps. PDDBTA showed hole mobilities of up to 4.1 × 10⁻² cm² V⁻¹ s⁻¹ in organic thin film transistors (OTFTs) as a p-channel material. As a donor in organic photovoltaics (OPVs), power conversion efficiencies (PCEs) of up to 2.18% were achieved, w...

N-type organic semiconductors are notoriously unstable in air, requiring the design of new materials that focuses on lowering their LUMO energy levels and enhancing their air stability in organic electronic devices such as organic thin-film transistors (OTFTs). Since the discovery of the notably air stable and high electron mobility polymer poly{[N...

Typical syntheses of conjugated polymers rely heavily on organometallic reagents and metal-catalyzed cross-coupling reactions. Here we show that an environmentally-benign aldol polymerization can be used to synthesize poly(bisisoindigo), an analog of polyisoindigo with a ring-fused structural repeat unit. Owing to its extended conjugation length, p...

This work reports development of yttrium doped copper oxide (Y‐CuO) as a new hole transport material with supplemented optoelectronic character. The pure and Y‐CuO thin films are developed through solid state method at 200oC and recognized as high performance p‐channel inorganic thin‐film transistors (TFTs). In sharp contrast, CuO is formed by oxid...

A highly efficient, solution processable, transparent semiconductor thin film of yttrium doped copper thiocyanate (Y(III)-CuSCN) has been developed using a simple and cost-effective spin coating modified method and investigated for its optical, electrical and electrochemical properties. The pure β-CuSCN, pin holes free compact thin films (40nm thic...

The copolymerization of CO2/propylene oxide (PO)/cyclohexene oxide (CHO) was carried out using a Zn-based heterogeneous catalyst, namely a supported multi-component zinc dicarboxylate. The monomer reactivity ratios of PO (rPO) to CHO (rCHO) were estimated using the Fineman-Ross and Kelen-Tudos graphical methods. The results showed that the rPO valu...

A novel electron deficient building block [2,2′-bithiophene]-4,4′-dicarboxamide (BTDCA) was designed to lower the highest occupied molecular orbital (HOMO) energy level of polythiophenes in order to achieve a higher open circuit voltage (Voc) and thus a higher power conversion efficiency in polymer solar cells (PSCs). BTDCA dibromo monomers were co...

We report the design and synthesis of two novel indigo donor-acceptor (D-A) polymers, PIDG-T-C20 and PIDG-BT-C20, comprising an indigo moiety that has intramolecular hydrogen-bonds as the acceptor building block and thiophene (T) and bithiophene (BT) as the donor building block, respectively. PIDG-T-C20 and PIDG-BT-C20 exhibited characteristic p-ty...

Understanding self-assembly behavior and resulting morphologies in block co-polymer films is an essential aspect of chemistry and materials science. Although the self-assembly of amorphous coil-coil block co-polymers is relatively well understood, that of semicrystalline block co-polymers where each block has distinct crystallization properties rem...

Solid-state packing and polymer orientation are critical for achieving high charge carrier mobility in organic thin-film transistors. Four side chain substituents, 2-octyldodecyl (−20), 4-octyltetradecyl (−22), 2-decyltetradecyl (−24), and 4-decylhexadecyl (−26), were synthesized to study the effect of side chains on the molecular crystallinity and...

We report the electrodeposition of cuprous oxide (Cu 2 O) films from cupric sulfate-lactate electrolytes at high pH 13.5 and their performance in all-oxide fluorine-doped tin oxide/Cu 2 O/aluminium-doped zinc oxide solar cells. The deposit grains are found to grow with rather randomly distributed <111> and <100> crystal orientations and have a poor...

A donor–acceptor (D–A) type conjugated polymer is comprised of one (or more) electron donating (D) building block and one (or more) electron accepting (A) block in the repeat unit. By selecting appropriate D and A units, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energies and other accompanying...

The recent development of high performance non-fullerene acceptors has relied on two main design principles: the calamitic design, where side-chains are arranged orthogonally to a planar chromophore, and the 3D design, where the chromophore is forced to adopt a non-planar structure. Until now, there has been no direct comparison of these designs. I...

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 bl...

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 resul...

Despite its very high theorctical capacity, the cathode material for the lithium-sulfur (Li-S) batteries still faces issues such as low sulfur utilization and poor long-term cycling stability due to the low conductivity of sulfur, polysulfide shutting effect as well as large volume change during discharge-charge processes. This work uses a novel mu...

The electron acceptor building block, N,N’-dialkoxynaphthalenediimide (NDIO), is for the first time used to develop an n-type polymer semiconductor P(NDIO2OD-T). The polymer exhibits unipolar electron charge transport with electron mobility up to 5.4× 10⁻³ cm² V⁻¹ s⁻¹ in organic thin film transistors (OTFTs) and shows good air-stability. When used...

A series of n-type semiconducting conjugated polymers based on naphthalene diimide (NDI) having three different side chains, 5-decylpentadecyl, 2-octyldodecyl and 4-(2-octyldodecyloxy)phenyl, were synthesized. Experimental results showed that the subtle structural changes at the side chains can influence the molecular packing, electron mobility, bl...

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...

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 w...

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...

This review highlights recent major progress in the development of organic semiconductors as electron transport n-channel materials in organic field transistors (OFETs). Three types of materials are discussed: 1) small molecules, 2) polymers, and 3) n-doped small molecules and polymers. Much efforts have been seen in the modification of known build...

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 cha...

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 hi...

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...

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 be...

A series of four low-bandgap polymers containing diketopyrrolopyrrole (DPP) and dithienopyrrole (DTP) functionalized with four different side chains of 4-phenyl, 4-octylphenyl, 4-(octyloxy)phenyl and 4-(octylthio)phenyl were synthesized. Subtle changes in the side chains of polymers are found to effectively affect the molecular stacking and crystal...

A series of electron-acceptor polymers, copolymers and blends were used in all-polymer BHJ photodetectors and the effect of acceptor compositions on the key device parameters of dark current density and photocurrent was investigated. Compared with acceptor polymers and polymer blends, the devices based on acceptor copolymer showed lowered dark curr...

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...

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 i...

In this study, we added several aromatic amine compounds as dopants to an ambipolar polymer semiconductor, PDBTAZ, and studied the charge transport behavior of the doped polymer thin films in organic thin film transistors. The trap energy (ET), which is the HOMO energy difference between the amine dopant and the polymer, was found related to the ho...

We present a design approach to maintain a stable voltage transfer characteristic in inkjet-printed complementary organic thin-film transistor logic inverters via device sizing. We use transistor-level design to help achieve stable logic gates, so that performance is less dependent on processing conditions and material properties that are difficult...

A series of conjugated polymers and oligomers previously used in organic photovoltaics and organic light-emitting diodes (OLEDs) have been examined for the first time as photoinitiators of polymerization. They address the present and future challenges facing photopolymerization: requirement of high extinction molar coefficients, absorption over the...

The formation of Cu2O films from an alkaline copper-lactate electrolyte using potentiostatic pulse electrodeposition has been conducted. The effects of the frequency, duty cycle, potential amplitude and electrolyte composition during pulsed electrodeposition on the resulting Cu2O morphology, crystal structure and orientation have been investigated...

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 t...

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-ind...

This study reports the synthesis and characterization of poly(3-hexylthiophene) (P3HT) from a direct heteroarylation polymerization of two isomeric monomers, 2-bromo-3-hexylthiophene (monomer 1) and 2-bromo-4-hexylthiophene (monomer 2). Using the Herrmann–Beller catalyst along with P(o-NMe2Ph)3, the resulting polymers are obtained in excellent yiel...

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 investigat...