Copolymers P1 Research Articles

New hole transport materials based on polybenzo[1,2-b:4,5-b']dithiophene polymers with different side chains for n-i-p perovskite solar cells

A series of new homo- and copolymers P1–P6 with the main chains comprised exclusively of benzo [1,2-b:4,5-b']dithiophene units were synthesized using Stille polycondensation reaction. The optical and electrochemical properties of P1–P6 polymers were studied to estimate the frontier orbitals energies and the Eg values. The obtained data demonstrate the possibility of controlling the electronic properties of polybenzo [1,2-b:4,5-b']dithiophenes by varying only the structure and combinations of solubilizing alkyl side chains. The polymers P1–P6 were evaluated as hole transport materials in n-i-p perovskite solar cells. The highest efficiency of 18.6 % was delivered by the cells with one of the designed polymers with an optimal combination of alternating mono- and dialkylthiophene substituents. The high photovoltaic performance and decent operational stability were achieved using polymer films without any doping, which paves a way to design of inexpensive and scalable dopant-free materials for perovskite solar cells.

Enhancing the Thermoelectric Properties of Conjugated Polymers by Suppressing Dopant-Induced Disorder.

Doping is a crucial strategy to enhance the performance of various organic electronic devices. However, in many cases, the random distribution of dopants in conjugated polymers leads to the disruption of the polymer microstructure, severely constraining the achievable performance of electronic devices. Here, it is shown that by ion-exchange doping polythiophene-based P[(3HT)1-x-stat-(T)x] (x=0 (P1), 0.12 (P2), 0.24 (P3), and 0.36 (P4)), remarkably high electrical conductivity of >400S cm-1 and power factor of >16µWm-1K-2 are achieved for the random copolymer P3, ranking it among highest ever reported for unaligned P3HT-based films, significantly higher than that of P1 (<40Scm-1, <4µWm-1K-2). Although both polymers exhibit comparable field-effect transistor hole mobilities of ≈0.1cm2V-1s-1 in the pristine state, after doping, Hall effect measurements indicate that P3 exhibits a large Hall mobility up to 1.2cm2V-1s-1, significantly outperforming that of P1 (0.06cm2V-1s-1). GIWAXS measurement determines that the in-plane π-π stacking distance of doped P3 is 3.44Å, distinctly shorter than that of doped P1 (3.68Å). These findings contribute to resolving the long-standing dopant-induced-disorder issues in P3HT and serve as an example for achieving fast charge transport in highly doped polymers for efficient electronics.

Alternating vs. random amphiphilic polydisulfides: aggregation, enzyme activity inhibition and redox-responsive guest release.

Herein, we report the synthesis of an alternating copolymer (ACP) with a bio-reducible amphiphilic polydisulfide backbone and highlight the impact of the alternating monomer connectivity on the self-assembly, morphology, chain-exchange dynamics, drug-release kinetics, and enzyme activity inhibition. Condensation polymerization between hydrophobic 1,10-bis(pyridin-2-yldisulfaneyl)decane and hydrophilic 2,3-mercaptosuccinic acid (1.04 : 1.00 ratio) generated amphiphilic ACP P1 (Mw = 8450 g mol-1, Đ = 1.3), which exhibited self-assembly in water, leading to the formation of an ultra-thin (height <5.0 nm) entangled fibrillar network. In contrast, structurally similar amphiphilic random copolymer P2 exhibited a truncated irregular disc-like morphology under the same conditions. It is postulated that due to the perfect alternating sequence of the hydrophobic and hydrophilic segments in P1, its immiscibility-driven aggregation in water leads to a pleated structure, which further assembles and forms the observed long fibrillar structures, similar to crystallization-driven self-assembly. In fact, wide-angle X-ray diffraction (WXRD) analysis of a lyophilized P1 sample showed sharp peaks, indicating its crystalline nature (approximately 37% crystallinity), and these were completely missing for P2. The effect of such distinct self-assembly on the chain-exchange dynamics was probed by fluorescence resonance energy transfer (FRET) using 3,3'-dioctadecyloxacarbocyanine perchlorate (DiO) and 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI) as the FRET-donor and -acceptor, respectively. For DiI- and DiO-entrapped solutions of P1, when mixed, no prominent FRET appeared even after 24 h. In sharp contrast, for P2, intense FRET emission occurred, and the FRET ratio (approximately 0.9) reached saturation in approximately 15 h, indicating the greatly enhanced kinetic stability of P1 aggregates. Glutathione-induced release of encapsulated Nile red showed much slower kinetics for P1 compared to that of P2, which was corroborated by the observed slow chain-exchange dynamics of the highly stable alternating copolymer assembly. Furthermore, the well-ordered assembly of P1 exhibited an excellent surface-functional group display (zeta potential of -32 mV compared to -14 mV for P2), which resulted in the effective recognition of the α-chymotrypsin (Cht) protein surface by electrostatic interaction. Consequently, P1 significantly (>70%) suppressed the enzymatic activity of Cht, while in the presence of P2, the enzyme was still active with >70% efficacy.

Enhanced Photothermal Property of NDI-Based Conjugated Polymers by Copolymerization with a Thiadiazolobenzotriazole Unit.

Solar steam generation (SSG) is a promising photothermal technology to solve the global water storage issue. The potential of π-conjugated polymers as photothermal materials is significant, because their absorption range can be customized through molecular design. In this study, naphthalenediimide (NDI) and thiadiazolobenzotriazole (TBZ) were employed as bifunctional monomers to produce conjugated polymers. There are two types of polymers, P1 and P2. P1 is based on NDI, while P2 is a copolymer of NDI and TBZ in a ratio of 9:1. Both polymers had high molecular weights and sufficient thermal stability. UV-vis-near-infrared (NIR) absorption spectra revealed that both polymers have large extinction coefficients ascribed to the NDI and TBZ chromophores. Notably, the absorption spectrum of P2 exhibited a significant red shift compared to P1, resulting in a narrow optical bandgap and absorption in the NIR range. This result suggested that P2 has a higher light absorption than P1. Photoluminescence (PL) spectra were measured to elucidate the conversion of the absorbed light into thermal energy. It was found that P2 has a reduced fluorescence quantum yield as a result of the TBZ unit, signifying a proficient conversion of the photothermal energy. Based on the results, it appears that the P2 film has a greater photothermal property compared to that of the P1 film. The surface temperature of the P2 film reached approximately 50 °C under the investigated conditions. In addition, copolymer P2 exhibited an impressive SSG efficiency of 72.4% under 1 sun (1000 W/m2) irradiation. All the results suggested that narrow bandgap conjugated polymers containing the TBZ unit are highly effective materials for achieving optimal performance in SSGs.

A GSH-activated AIE-based polymer photosensitizer for killing cancer cells.

Developing efficient photosensitizers which are sensitive to therapeutic tumor signals, but non-toxic to normal cells has always been a tremendous challenge in photodynamic therapy (PDT) process. Herein, a novel copolymer P1 was developed by ring-opening metathesis polymerization (ROMP) with disulfide bond linked ferrocene-norbornene dyad NB-SS-PyFc and the aggregation-induced emission (AIE) fluorephore anchored norbornene NB-TPE, and its nanoparticles (NPs) were obtained by using the amphiphilic Pluronic F-127 as the surfactant via a nanoprecipitation method. The P1 NPs show a weak emission and a low 1O2 generation for the quenching effect from the ferrocene moiety to the AIE group. However, the addition of GSH can recover the AIE fluorephore emission and 1O2 generation for cleavage the disulfide bond. Importantly, P1 NPs have been used for image-guided cancer cells apoptosis for the GSH activated 1O2 generation.

Ferrocene-anchored poly(norbornene) for ATP sensing using indicator displacement assay

A new amphiphilic polynorbornene-based copolymer P1 was designed and synthesized successfully by ring-opening metathesis polymerization (ROMP) of polyethylene glycol (PEG) containing monomer NB-PEG and ferreocene-anchored monomer NB-Fc. The copolymer P1 can bind with anionic uranine dye (UD) through multiple interactions to form no fluorescent P1/UD nano-structure ensemble in aqueous solution. The P1/UD ensemble can be used as indicator displacement assay (IDA) for ATP detection with a high sensitivity and selectivity. Upon the addition of ATP, the fluorescence is significant enhanced for displacement of UD from P1/UD ensemble. The LOD value of P1/UD ensemble toward ATP is as low as 35.9 nM. The P1/UD ensemble exhibits an excellent photo-stability and biocompatibility, and has been successfully used for imaging ATP in living cells.

Retina‐Inspired Organic Photonic Synapses for Selective Detection of SWIR Light

AbstractPhotonic synapses with the dual function of optical signal detection and information processing can simulate human visual system. However, photonic synapses with selective detection of short‐wavelength infrared (SWIR) light have never been reported, which can not only broaden the human vision region but also integrate neuromorphic computation and infrared optical communication. Here, organic photonic synapses based on a new donor‐acceptor copolymer P1 are fabricated, which exhibit excellent synaptic characteristics with selective detection for SWIR and extremely low energy consumption (2.85 fJ). The working mechanism is rooted in energy level barriers and unbalanced charge transportation. Moreover, these photonic synapses demonstrate excellent performance in multi‐signal logic editing, letter imaging and memory with noise reduction function. This contribution provides ideas of constructing selective‐response synapses for artificial visual system and neuromorphic computing.

Retina-Inspired Organic Photonic Synapses for Selective Detection of SWIR Light.

Photonic synapses with the dual function of optical signal detection and information processing can simulate human visual system. However, photonic synapses with selective detection of short-wavelength infrared (SWIR) light have never been reported, which can not only broaden the human vision region but also integrate neuromorphic computation and infrared optical communication. Here, organic photonic synapses based on a new donor-acceptor copolymer P1 are fabricated, which exhibit excellent synaptic characteristics with selective detection for SWIR and extremely low energy consumption (2.85 fJ). The working mechanism is rooted in energy level barriers and unbalanced charge transportation. Moreover, these photonic synapses demonstrate excellent performance in multi-signal logic editing, letter imaging and memory with noise reduction function. This contribution provides ideas of constructing selective-response synapses for artificial visual system and neuromorphic computing.

Cyclopenta[c]thiophene- and Diketopyrrolopyrrole-Based Red-Green-Blue Electrochromic Polymers

Cyclopenta[c]thiophene (CPT)-based polymers are potential candidates in organic electronics. Here, we report the first solution-processable red homopolymer (P1) of a thiophene-capped derivative of CPT (DHTCPT), and a blue homopolymer (P2) of N-substituted thienodiketopyrrolopyrrole (DEHTDPP). Additionally, by alternatingly copolymerizing the DHTCPT and DEHTDPP units, we achieved the green copolymer P3, thus completing the red-green-blue color wheels. We have shown experimentally and computationally (time-dependent density functional theory and natural bond orbital calculations) that P1 and P2 have very different optoelectronic features. However, in a donor–acceptor (D–A) copolymer P3, the optoelectronic properties have been tuned significantly to keep it in an intermediate range of P1 and P2. P2 and P3 absorb throughout the whole UV-vis range of the solar spectrum. Furthermore, all polymers showed electrochromism to switch colors between neutral and polaronic states in solution. For P1, the maximum optical contrast (%ΔT) was observed for the SOMO→LUMO transition, whereas P3 displayed the maximum %ΔT at the HOMO→LUMO transition.

Influence of the Poly(ethylene Glycol) Methyl Ether Methacrylates on the Selected Physicochemical Properties of Thermally Sensitive Polymeric Particles for Controlled Drug Delivery.

Thermosensitive copolymers P1-P5 of N-isopropylacrylamide (NIPA) and poly(ethylene glycol) methyl ether methacrylates (PEGMEMs) were synthesized via surfactant-free precipitation polymerization (SFPP) using ammonium persulfate (APS) at 70 °C. The polymerization course was evaluated by the conductivity. The hydrodynamic diameters and the polydispersity indexes (PDI) of P1-P5 in the 18-45 °C range, which were assessed via dynamic light scattering (DLS), were at 18° (nm): 26.07 ± 0.54 (PDI 0.65 ± 0.03), 68.00 ± 1.10 (PDI 0.56 ± 0,02), 45.12 ± 0.57 (PDI 0.51 ± 0.03), 62.78 ± 0.40 (PDI 0.53 ± 0.003), and 92.95 ± 1.56 (PDI 0.60 ± 0.04), respectively. The lower critical solution temperatures ranged from 31 to 33 °C. The electrophoretic mobilities estimated the zeta potential in the 18-45 °C range, and at 18 °C, they were (mV): -4.64 ± 1.30, -6.91 ± 2.67, -5.85 ± 3.17, -2.28 ± 0.30, and -3.60 ± 0.96 for P1-P5, respectively. The polymers were characterized by Attenuated Total Reflectance Fourier-Transform Infrared spectroscopy (ATR-FTIR), H nuclear magnetic resonance (1H NMR), thermogravimetric analysis (TGA/DTA), Differential Scanning Calorimetry (DSC), and powder X-ray diffraction analysis (PXRD). Stable amorphous polymers were obtained. We conclude that the length of the co-monomer chain nonlinearly influences the properties of the obtained thermosensitive polymer nanostructures.

Lipophilic poly(glycolide) blocks in morpholin-2-one-based CARTs for plasmid DNA delivery: Polymer regioregularity, sequence of lipophilic/polyamine blocks, and nanoparticle stability as factors of transfection efficiency

In the present work, monosubstituted glycolides (G2–G4) derived from the (L)-tyrosine-based glycolide G1 and containing –CH2C6H4OR substituents (R = decanoyl, oleoyl, C(O)CH(n-C6H13)(n-C8H17)) have been used to design biodegradable and biocompatible lipophilic blocks in N-BOC-morpholin-2-one (M1)-based Charge-Altering Releasable Transporters (CARTs). Copolymers of dodecyl carbonate C1 (the ‘benchmark’ lipophilic comonomer) and M1, having direct (P1) or inverse (P2) block sequences; copolymers of G2–G4 and M1, having inverse block sequences and irregular, head-to-head in places, microstructures of the poly(glycolide) blocks (P3–P7); and copolymers of G2 and M1, having solely alternating head-to-tail microstructures of the poly(glycolide) blocks and direct (P8) or inverse (P9) block sequences, have been synthesized. DLS studies have shown that, after deprotection, the copolymers P1′–P9′ form liposomal particles in aqueous medium, differing considerably in their colloidal behavior, which depended on the length of the polyamine fragment and the nature of the lipophilic block. The ability of P1′–P9′ to deliver the plasmid pEGFP-N1 into cultured HEK293T cells (transfection efficiency) has been assessed at N/P ratios of the corresponding polyplexes in the range 1:1–50:1 by flow cytometry and further confirmed by fluorescence microscopy. Transfection experiments have demonstrated that the CARTs P1′, P4′, and P6′, containing ten (2-oxyethyl)glycine fragments, are about four times more efficient in delivering pDNA than commercial agents (Lipofectamine™ 3000, PEI MAX, X-tremeGENE™ 9, and GenJet™ In Vitro DNA Transfection Reagent). A correlation between the results of those studies and DLS / ζ-potential measurements has been established for P1′ and P4′: the transfection is efficient, if N/P ratios are equal to those favoring ζ-potential inversion at physiological pH. We conclude that glycolide-based CARTs show significant promise for further development as non-viral NA delivery vehicles and that DLS should be regarded as an efficient method of primary screening of amphiphilic copolymers, as well as copolymer-NA complexes and formulations thereof.

Secondary amine pendent β-peptide polymers realizing antimicrobial surfaces to prevent bacterial infection of implants

Antimicrobial coatings covalently grafted on the implant surfaces are considered to be one of the powerful weapons to prevent implant-associated infections. β-Peptide polymers and host defense peptide mimicking polymers are considered promising candidates to fight against drug-resistant bacteria. Here, we compared the antimicrobial activity of Au surface modified by these β-peptide polymers containing primary, secondary, and tertiary amino groups in the side chains. Copolymer P3 containing secondary amino groups was found to have high antibacterial activity. P3-modified thermoplastic polyurethane (TPU) can serve as a promising antimicrobial material for practical application, because of its effective prevention of TPU-related infection and the promotion of host cell growth in the subcutaneous implant infection model.

Multi-stimuli responsive poly(N-isopropyl-co-tetraphenylethene) acrylamide copolymer mediating AIEgens by controllable tannic acid

Copolymerization of N-isopropylacrylamide (NIPAM) and tetraphenylethene (TPE) acrylamide monomers produced aggregation-induced emission (AIE) active copolymers P1 , P2 , and P3 with relatively lower molecular weights (6000). Like poly-N-isopropylacrylamide (p-NIPAM), an aqueous solution of copolymers ( P1-P3 ) responds to temperature and undergoes a change in fluorescence intensity due to conformational transition (swelling/shrinking) below and above their lower critical solution temperature (LCST), respectively. The LCST of p-NIPAM (32 °C) shifted downward upon the incorporation of TPE in the copolymer chains depending on the concentration of TPE . Compared to P1 , the fluorescence response increased to a five-fold enhancement with increasing concentrations of tannic acid ( TA ) owe to the form of the P1-TA complex. Furthermore, the P1-TA complex showed a surprising change in fluorescence response under the effect of temperature and pH value. The conformational transitions of P1-TA were also studied by dynamic light scattering (DLS). DLS measurements for the P1-TA complex justified its fluorescence response based on particle size at different concentrations and pH value. Such stimuli-responsive AIE-active copolymers find potential applications in drug delivery systems for monitoring loading and release processes by fluorescence. • Compared to P1, the fluorescence intensity of AIE-active P1-TA complex increased to a five-fold enhancement. • A multi-stimuli response on temperature and pH value based on intermolecular hydrogen bonding interaction. • The interpenetrating networks can be formed without using two polymer chains or more.

PH-Responsive Emission of Novel Water-Soluble Polymeric Iridium(III) Complexes.

The synthesis and characterization of water-soluble copolymers containing N,N-dimethylacrylamide (DMAM) and a vinylic monomer containing an Iridium(III), Ir(III), complex substituted with the quinoline-based unit 2-(pyridin-2-ylo)-6-styrene-4-phenylquinoline (VQPy) as ligand are reported. These copolymers were prepared through pre- or post-polymerization complexation of Ir(III) with the VQPy units. The first methodology led to copolymer P1 having fully complexed VQPy units, whereas the latter methodology allowed the preparation of terpolymers containing free and Ir(III)-complexed VQPy units (copolymer P2). The optical properties of the copolymers were studied in detail through UV-Vis and photoluminescence spectroscopy in aqueous solution. It is shown that the metal-to-ligand charge transfer (ΜLCT) emission is prevailing in the case of P1, regardless of pH. In contrast, in the case of terpolymer P2 the MLCT emission of the Ir(III) complex is combined with the pH-responsive emission of free VQPy units, leading to characteristic pH-responsive color changes under UV illumination in the acidic pH region.

Aminoquinoline-anchored polynorbornene for sequential fluorescent sensing of Zn2+ and ATP

A novel aminoquinoline functionalized norbornene (1) and its ring-opening metathesis polymerization (ROMP) copolymer P1 have been designed and synthesized. The polymer probe P1 can self-assemble nano aggregation in aqueous solution. The fluorescent experiments revealed that both 1 and P1 show a ratiometric fluorescence response toward Zn2+ over other mental ions in Tris-HCl buffer solution, with the polymer probe P1 shows a better photostability and higher binding affinity than that of the small molecular probe 1. Furthermore, the in situ formed P1-Zn2+ ensemble was successfully used as the secondary sensor for ATP. P1 is also successfully used for monitoring intracellular Zn2+ and ATP in living cells.

Multi-stimuli responsive fluorescence of amphiphilic AIEgen copolymers for ultrafast, highly sensitive and selective copper ion detection in water

Novel multi-stimuli responsive fluorescence sensors based on amphiphilic copolymers containing hydrophilic N-isopropylmethacrylamide (NIPAM) and AIEgenic tetraphenylethylene-dipicolylamine (TPEDPA) monomers attached to side-chains of copolymers are synthesized. Two copolymers poly(NIPAM)x-co-(TPEDPA)y prepared by free radical polymerization with different molar ratios of monomers NIPAM and TPEDPA (i.e., x:y = 60:1 and 175:1 for P1 and P2, respectively) show good solubilities in organic solvents and water, which exhibit strong cyan fluorescence at 466 nm in aggregation and solid states due to AIE behaviors of TPE units. Upon various external stimuli (temperatures and acid/base conditions), P1 and P2 possess excellent reversible thermo- and pH-responsive fluorescence turn-off/on cyan emissions of TPE units. In addition, with DPA receptor, P1 and P2 are applied as ultrafast, selective and sensitive fluorescence probes for copper ion detection in water based on the TPE fluorescence quenching via photoinduced electron transfer (PET) phenomena, which can be recovered by the addition of disodium ethylenediaminetetraacetate solution. Owing to good water solubilities, amphiphilic copolymers P1 and P2 (containing only 1.6 and 0.6 % molar ratios of AIEgen) exhibit significant sensing towards Cu2+ with very prominent limit of detection values (LOD = 57 and 72 nM, respectively), which are much better than that of hydrophobic monomer TPEDPA (590 nM). Moreover, the fluorescence quenching of TPE units due to PET phenomena is further confirmed by theoretical calculations. Additionally, as an excellent quenching fluorescence sensor with good biocompatibility of P1, its recognition of copper ion and bio-imaging applications in living cells are also reported in this research.

Rhodamine-anchored poly(norbornene) for fluorescent sensing of ATP

A fluorescent poly (norbornene)-based copolymer probe P1, which was obtained via ring-opening metathesis polymerization (ROMP) of a PEG-anchored norbornene monomer NB-PEG with a rhodamine-functionalized monomer NB-RB, has been designed and synthesized. Owing to its amphiphilic property, copolymer P1 self-assembles nanostructure aggregations in aqueous solution with a weak emission. Upon addition of ATP, visual color change from colorless to red and a large fluorescence enhancement were observed for the ring-opening of rhodamine spirolactam mechanism. This probe shows a good photostability, and has been successfully applied for imaging of ATP level in living SMMC cells.

Self-assembly and in vitro drug release behaviors of amphiphilic copolymers based on functionalized aliphatic liquid crystalline polycarbonate with pH/temperature dual response

Amphiphilic copolymers Pn (n = 1–3) with mPEG as hydrophilic segment and aliphatic polycarbonate as hydrophobic segment were designed and synthesized successfully, and the results of POM, XRD and DSC showed that only P3 showed liquid crystalline (LC) phase. Due to the carboxyl and cholesteric LC groups in the side chain of the polycarbonate, the micelles prepared in this study were endowed with pH and temperature dual response. The effects of different conditions such as selective solvents, copolymer concentration, pH, temperature, the structure and LC mesophase on the self-assembly behavior and drug loading properties of the copolymer micelles were explored. It was found that the critical water concentration for self-assembly, the particle size and morphology of the micelles could be effectively controlled by changing the above conditions. Moreover, introducing LC properties into the copolymer could effectively decrease the critical water concentration for self-assembly and elevate the drug loading content. The DOX was conjugated to the copolymers by hydrogen bonds, and the copolymer P3 could form regular fusiform micelles after loading with DOX. Moreover, P3-DOX micelles could be endocytosed into cells and the drug release behavior could be triggered by the weak acid condition and elevated temperature. Therefore, the P3-DOX micelles could achieve a pH-triggered rapid drug release under weakly acidic conditions of the tumor cells. This kind of controllable micelles will have a potential application as drug-carriers in drug delivery.

Multipurpose conjugated block copolymers based on novel triphenylylamine derivatives and squaric acid for electrochromic and resistive memory devices

Here, we synthesized two kinds of novel conjugated block copolymers P1 and P2 by reacting squaric acid and three kinds of homemade diamine monomers. The polymers P1 and P2 can be dissolved in many normal organic solvents and form films by solution-cast method with high mechanical properties. In addition, when the 10% weight loss is selected as a reference point, the polymers P1 and P2 showed the thermal decomposition temperatures at around 309 and 312 °C, respectively. The polymer films exhibit high coloration efficiencies (CE) (262–282 cm2 C−1) and good cyclic stabilities. In addition, the ITO/polymer/Al sandwich memory devices exhibited non-volatile resistive switching behaviors with low write, erase voltages (more than −0.6 V and less than 3.1 V, respectively), good ON/OFF ratio (843 and 1435) and reliable cycling endurance (more than 30,000 cycles). These properties illustrate that the polymers could be considered as potential electrode materials for both electrochromic and resistive memory devices.

Indacenodithiazole-Ladder-Type Bridged Di(thiophene)-Difluoro-Benzothiadiazole-Conjugated Copolymers as Ambipolar Organic Field-Effect Transistors

A series of four donor–acceptor conjugated copolymers P1–P4 with linear and branched side chains based on a ladder-type indacenodithiazole (IDTz) moiety containing an electron-deficient thiazole unit are copolymerized with di-2-thienyl-2,1,3-benzothiadiazole (DTBT) and 4,7-di(thien-2-yl)-5,6-difluoro-2,1,3-benzothiadiazole (DTBTff) as building blocks. Their optical, electrochemical, and thermal properties and charge transport behavior in organic field-effect transistors (OFETs) are studied. All copolymers exhibit nearly identical features in solution with good solubility. In the solid state, P1 does not exhibit a significant shift, while P3 shows a 27 nm red shift, thus illustrating the influence of the side chain. In the case of copolymers P1 and P2 having linear side chains, there is a clear effect of fluorination on the film morphology, while it is less pronounced in the case of polymers P3 and P4 having branched side chains. All copolymers P1–P4 have similar highest occupied molecular orbitals regardl...