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The development of semiconducting polymers with good processability in green solvents and competitive electrical performance is essential for realizing sustainable large-scale manufacturing and commercialization of organic electronics. A major obstacle is the processability-performance dichotomy that is dictated by the lack of ideal building blocks with balanced polarity, solubility, electronic structures, and molecular conformation. Herein, through the integration of donor, quinoid and acceptor units, an unprecedented building block, namely TQBT, is introduced for constructing a serial of conjugated polymers. The TQBT, distinct in non-symmetric structure and high dipole moment, imparts enhanced solubility in anisole-a green solvent-to the polymer TQBT-T. Furthermore, PTQBT-T possess a highly rigid and planar backbone owing to the nearly coplanar geometry and quinoidal nature of TQBT, resulting in strong aggregation in solution and localized aggregates in film. Remarkably, PTQBT-T films spuncast from anisole exhibit a hole mobility of 2.30 cm2 V-1 s-1, which is record high for green solvent-processable semiconducting polymers via spin-coating, together with commendable operational and storage stability. The hybrid building block emerges as a pioneering electroactive unit, shedding light on future design strategies in high-performance semiconducting polymers compatible with green processing and marking a significant stride towards ecofriendly organic electronics.

One grand challenge for printed organic electronics is the development of a knowledge platform that describes how polymer semiconductors assemble from solution, which requires a unified picture of the complex interplay of polymer solubility, mass transport, nucleation and, e.g., vitrification. One crucial aspect, thereby, is aggregate formation, i.e., the development of electronic coupling between adjacent chain segments. Here, it is shown that the critical aggregation temperatures in solution (no solvent evaporation allowed) and during film formation (solvent evaporation occurring) are excellent pointers to i) establish reliable criteria for polymer assembly into desired aggregates, and ii) advance mechanistic understanding of the overall polymer assembly. Indeed, important insights are provided on why aggregation occurs via a 1‐ or 2‐step process depending on polymer solubility, deposition temperature and solvent evaporation rate; and the selection of deposition temperatures for specific scenarios (e.g., good vs bad solvent) is demystified. Collectively, it is demonstrated that relatively straightforward, concurrent in situ time‐resolved absorbance and photoluminescence spectroscopies to monitor aggregate formation lead to highly useful and broadly applicable criteria for processing functional plastics. In turn, improved control over their properties and device performance can be obtained toward manufacturing sensors, energy‐harvesting devices and, e.g., bioelectronics systems at high yield. [ABSTRACT FROM AUTHOR]

Organic electroactive materials, particularly semiconducting polymers, are at the forefront of emerging organic electronics. Among the plethora of unique features, the possibility to formulate inks out of these materials is particularly promising for the large‐scale manufacturing of electronics at lower cost on a variety of soft substrates. While solution deposition of semiconducting materials is promising for developing printed electronics, the environmental footprint of the materials and related devices needs to be considered to achieve sustainable manufacturing. Towards the development of greener printed electronics, this work investigates the utilization of a non‐toxic, environmentally‐friendly solvent, namely branched polyethylene (BPE), to formulate semiconducting inks. Focusing on a diketopyrrolopyrrole‐based (DPP) semiconducting polymer, shellac as dielectric, and BPE as the solvent, solutions were prepared in different concentrations and their rheological properties were characterized. Then, printing on polyethylene terephthalate (PET) substrates using two different techniques was performed to fabricate organic field‐effect transistors (OFETs). Both printing techniques yielded OFETs with good performance and device characteristics, averaging approximately 10−2 and 10−4 cm2 V−1 s−1, respectively, for slot‐die coating and direct‐ink writing deposition. Notably, despite some difference in threshold voltages, OFETs produced via slot‐die coating and direct‐ink writing showed comparable charge mobilities to previously reported OFETs prepared from similar materials, particularly those prepared on silicon dioxide wafers. Overall, this work confirms the suitability of BPE to formulate semiconducting inks to develop printed electronics in a greener manner. The printing methodology developed in this work also open new avenues for the design of functional printed electronics and related technologies. [ABSTRACT FROM AUTHOR]

This study introduces the first fluorene‐flanked diketopyrrolopyrrole (FDPP)‐based semiconducting polymers, named Boc‐FDPP‐CoMs (CoM = TT or BT), synthesized via copolymerization of tert‐butoxycarbonyl (t‐Boc)‐substituted FDPP as the acceptor unit with thieno[3,2‐b]thiophene (TT) or bithiophene (BT) as the donor comonomers. The incorporation of t‐Boc groups addresses challenges related to poor solubility and polymer backbone twisting associated with the FDPP building block. While Boc‐FDPP‐CoMs demonstrate solubility in common organic solvents, facilitating favourable solution‐processability for uniform film fabrication, they exhibit significant backbone twisting, leading to poor charge transport properties. Post‐deposition thermal annealing at a mild temperature as low as 170°C conveniently removes t‐Boc groups. The resulting t‐Boc‐free copolymers, NH‐FDPP‐TT and NH‐FDPP‐BT, exhibit hole mobilities up to 5.0 × 10−3 and 2.2 × 10−3 cm2 V−1 s−1 in organic field effect transistors (OFETs), respectively, representing a substantial increase compared to their counterparts with t‐Boc groups. This study underscores a meticulously designed strategy for achieving solution solubility and backbone coplanarity through side‐chain engineering for FDPP and potentially other sterically demanding building blocks to construct high‐performance semiconducting polymers for OFETs and other applications. [ABSTRACT FROM AUTHOR]

The optoelectronic properties of semiconducting polymers and device performance rely on a delicate interplay of design and processing conditions. However, screening and optimizing the relationships between these parameters for reliably fabricating organic electronics can be an arduous task requiring significant time and resources. To overcome this challenge, Polybot is developed—a robotic platform within a self‐driving lab that can efficiently produce organic field‐effect transistors (OFETs) from various semiconducting polymers via high‐throughput blade coating deposition. Polybot not only handles the fabrication process but also can conduct characterization tests on the devices and autonomously analyze the data gathered, thus facilitating the rapid acquisition of data on a large scale. This work leverages the capabilities of this platform to investigate the fabrication of OFETs using hydrogen bonding‐containing semiconducting polymers. Through high‐throughput fabrication and characterization, various data trends are analyzed, and large extents of anisotropic charge mobility are observed in devices. The materials are thoroughly characterized to understand the role of processing conditions in solid state and electronic properties of these organic semiconductors. The findings demonstrate the effectiveness of automated fabrication and characterization platforms in uncovering novel structure–property relationships, facilitating refinement of rational chemical design, and processing conditions, ultimately leading to new semiconducting materials. [ABSTRACT FROM AUTHOR]

In this work, planar-heterojunction organic phototransistors (OPT) have been constructed from solution process, by combining a semiconducting diketopyrrolopyrrole polymer PDVT-10 and a novel carbon nano-material-carbon quantum dots (CQDs). The PDVT-10/CQDs planar heterojunction films, possessing the optical properties of both PDVT-10 and CQDs, reveal strong optical absorption in a wide spectral region from ultraviolet to near infra-red. Compared with pristine PDVT-10 phototransistors, such planar-heterojunction OPTs exhibit a remarkably higher performance on broad-spectrum photo-detection, with a photoresponsivity of 2.6 x 104 A/W, a specific detectivity of 2.4 x 1013 Jones, and maximum light sensitivity higher than 104 under the 450-nm laser irradiation, as well as with a responsivity of 4.4x104 A/W and a specific detectivity of 1.2 x1013 Jones under the 808-nm laser irradiation. Based on the study of the photo-response mechanism for these devices, the performance improvement of the PDVT-10/CQDs based OPTs should be attributed to the favorable energy level alignment at the PDVT-10/CQDs interfaces, which enhances interfacial exciton dissociation and charge separation, meanwhile effectively suppresses the hole-electron recombination in the light-absorption layer. Furthermore, the formation of efficient carrier conduction pathway is benefited from high hole-mobility of PDVT-10 for the OPT performance enhancement. Our work offers a valuable avenue for the development of high performance light detectors. [ABSTRACT FROM AUTHOR]

Stretchable conjugated polymers with conjugation break spacers (CBSs) synthesized via random terpolymerization have gained considerable attention because of their efficacy in modulating mobility and stretchability. This study incorporates a series of dianhydrohexitol diastereomers of isosorbide (ISB) and isomannide (IMN) units into the diketopyrrolopyrrole‐based backbone as CBSs. It is found that the distorted CBS (IMN) improves the mobility–stretchability properties of the polymer with a highly coplanar backbone, whereas the extended CBS (ISB) enhances those of the polymer with a noncoplanar backbone. Additionally, the different configurations of ISB and IMN sufficiently affect the solid‐state packing, aggregation capabilities, crystallographic parameters, and mobility–stretchability properties of the polymer. The IMN‐based polymers exhibit the highest mobility of 1.69 cm2 V−1 s−1 and crystallinity retentions of (85.7, 78.6)% under 20% and 60% strains, outperforming their ISB‐based or unmodified counterparts. The improvement is correlated with a robust aggregation capability. Furthermore, the CBS content affects aggregation behavior, notably affecting mobility. This result indicates that incorporating CBSs into the polymer can enhance backbone flexibility via movement and rotation of the CBS without affecting the crystalline regions. [ABSTRACT FROM AUTHOR]

Photodetectors operating across the near‐ to short‐wave infrared (NIR–SWIR, λ = 0.9–1.8 µm) underpin modern science, technology, and society. Organic photodiodes (OPDs) based on bulk‐heterojunction (BHJ) active layers overcome critical manufacturing and operating drawbacks inherent to crystalline inorganic semiconductors, offering the potential for low‐cost, uncooled, mechanically compliant, and ubiquitous infrared technologies. A constraining feature of these narrow bandgap materials systems is the high noise current under an applied bias, resulting in specific detectivities (D*, the figure of merit for detector sensitivity) that are too low for practical utilization. Here, this study demonstrates that incorporating wide‐bandgap insulating polymers within the BHJ suppresses noise by diluting the transport and trapping sites as determined using capacitance‐frequency analysis. The resulting D* of NIR–SWIR OPDs operating from 600–1400 nm under an applied bias of −2 V is improved by two orders of magnitude, from 108 to 1010 Jones (cm Hz1/2 W−1), when incorporating polysulfone within the blends. This broadly applicable strategy can reduce noise in IR‐OPDs enabling their practical operation and the realization of emerging technologies. [ABSTRACT FROM AUTHOR]

The side effects of antibiotics on humans and ambient environment have aroused huge attention from related researchers. In this article, the performances and mechanism of photodegradation of tetracycline (TC) were examined by employing semiconducting polymer microspheres obtained with an emulsion-solvent-evaporation approach. Under the excitation of visible-light, as-prepared semiconducting polymer microspheres show outstanding photocatalytic ability and excellent stability for TC-derived antibiotics. Compared with corresponding semiconducting polymer powders, the adsorption and photocatalytic rates of TC by polymer-based microspheres increased by 8.07 and 6.79 times, respectively. These performance improvements in photodegradation are mainly ascribed to the larger specific surface area and longer conjugation length of as-prepared spherical structure. Characterization of electron spin resonance demonstrates that the primary active species functioning for efficient photodegradations of TC are superoxide radical, hydrogen peroxide, and hole. These results indicated that semiconducting polymer microspheres can serve as efficient photocatalysts for removing destructive TC-derived antibiotics from wastewaters. [ABSTRACT FROM AUTHOR]

Sub‐monolayer networks of the electron‐transporting semiconducting polymer poly([N,N'‐bis(2‐octyldodecyl)‐naphthalene‐1,4,5,8‐bis(dicarboximide)−2,6‐diyl]‐alt‐5,5′‐(2,2′‐bithiophene)) (P(NDI2OD‐T2)) are realized through judicious choice of spin‐coating solvent and control of solution concentration. These sub‐monolayer networks provide a platform to study the effects of surface coverage, network connectivity, and orientational order on charge transport. It is found that charge transport through semiconducting polymer networks depends not only on the coverage/concentration of the material but also on the nature of the conduction paths themselves. Down to 40% surface coverage, current measured in a field‐effect architecture decreases in line with the decrease in surface coverage, but drops precipitously below a surface coverage of 40%. Below 40% surface coverage, there is a marked decrease in network connectivity (quantified through the branching point density) and a decrease in orientational order. Furthermore, an increase in the density of dangling branches (dead ends) is also seen with decreasing surface coverage. Additional supporting data in the form of grazing incidence wide‐angle X‐ray scattering (GIWAXS), optical spectroscopy, and charge modulation spectroscopy are presented, which help to establish that long‐range interconnectivity rather than local morphology dominates charge transport in P(NDI2OD‐T2) sub‐monolayers as well as thin films. [ABSTRACT FROM AUTHOR]

Context: Due to the widely known positive contributions of the quinoxaline group in organic semiconductors, we conducted a fully computational study using quantum mechanical methods to investigate the effect of quinoxaline in the electron acceptor unit with the combination of different chalcogen atoms on the band gap of a series of donor–acceptor-donor type conjugated polymers. Using density functional theory, we mainly calculated the electronic band gap values of the structures containing four different chalcogen atoms (O, S, Se, and Te) in the electron donor and acceptor units. While chalcogendiazoloquinoxaline groups were used as the electron acceptor units, furan, thiophene, selenophene, and tellurophene were used as the donor units. Our theoretical results showed that the use of heavy chalcogen atoms in both donor and acceptor units resulted in a low band gap. Besides this, the effect of heavy chalcogen atoms used in the electron donor units is much more pronounced compared to the ones used in the acceptor units. More importantly, our findings proved that the inclusion of the chalcogendiazoloquinoxaline group instead of benzochalcogenadiazole as the acceptor unit significantly decreases the electronic band gap of the conjugated polymer. The lowest band gap was found to be 0.10 eV for the 4,9-di(tellurophen-2-yl)-[1,2,5]telluradiazolo[3,4-g]quinoxaline polymer. Methods: Conformational analysis of the monomers and their corresponding oligomers was performed at the B3LYP/LANL2DZ level of theory. Then, long-range corrected hybrid functional LC-BLYP in a combination with the LANL2DZ basis set was utilized for the calculation of electronic properties and HOMO and LUMO energy gaps of monomers and oligomers through the reoptimization of the lowest energy conformers obtained from the B3LYP/LANL2DZ calculations in the previous step. All energy minimum structures were confirmed through vibrational frequency analysis at both calculation levels. The Gaussian 09 rev. D.01 software was used for all calculations, and GaussView 5.0.9 for visualizations. [ABSTRACT FROM AUTHOR]

The strategic design of solution‐processable semiconducting polymers possessing both matched energy levels and elevated glass transition temperatures is of urgent importance in the progression of thermally robust n‐i‐p perovskite solar cells with efficiencies exceeding 25 %. In this work, we employed direct arylation polymerization to achieve the high‐yield synthesis of three aza[5]helicene‐derived copolymers with distinct HOMO energy levels and exceptional glass transition temperatures. Upon integration of these semiconducting polymers into formamidinium lead triiodide‐based perovskite solar cells, marked disparities in photovoltaic parameters manifest, primarily stemming from variations in the electrical conductivity and film morphology of the hole transport layers. The p‐A5HP‐E‐POZOD‐E copolymer, featuring a main chain comprising alternating repeats of aza[5]helicene, ethylenedioxythiophene, phenoxazine, and ethylenedioxythiophene, attains an initial average efficiency of 25.5 %, markedly surpassing reference materials such as spiro‐OMeTAD (23.0 %), PTAA (17.0 %), and P3HT (11.6 %). Notably, p‐A5HP‐E‐POZOD‐E exhibits a high cohesive energy density, resulting in enhanced Young's modulus and diminished external species diffusion coefficients, thereby conferring perovskite solar cells with exceptional 85 °C tolerance and operational stability. [ABSTRACT FROM AUTHOR]

In this work, we aim to deliver a comprehensive review of the past and current fabrication and subsequent structural characterization of single crystals of established semiconducting polymers and oligomers while maintaining extra emphasis on the crystals' resulting optoelectronic properties, including charge carrier mobility, conductivity, photovoltaic capability, and the ability to absorb light. [ABSTRACT FROM AUTHOR]

Extended π-conjugation with backbone-planarity-driven π-π stacking dominates charge transport in semiconducting polymers (SCPs). The roles of SCP film morphology and macromolecular conformation concerning the substrate in influencing charge transport and its impact on device performance have been a subject of extensive debate. Face-on SCPs promote out-of-plane charge transport primarily through π-π stacking, with conjugated polymeric chains assisting transport in connecting crystalline domains, whereas edge-on SCPs promote in-plane charge transport primarily through conjugation and π-π stacking. In this work, we fabricated three different types of devices, namely, organic field effect transistors, organic Schottky diodes, and organic bistable memristors, as representatives of planar and vertical devices. We demonstrate that a planar device, i.e., an organic field effect transistor, performs well in an edge-on conformation exhibiting a field-effect mobility of 0.12 cm2V−1s−1 and on/off ratio >104, whereas vertical devices, i.e., organic Schottky diodes and organic memristors, perform well in a face-on conformation, exhibiting exceptionally high on/off ratios of ~107 and 106, respectively. [ABSTRACT FROM AUTHOR]

Polymer semiconductors frequently form crystals or mesophases with lamellae, that comprise alternating layers of stacked backbones and side chains. Controlling lamellar orientation in films is essential for obtaining efficient charge carrier transport. Herein, lamellar orientation is investigated in an application‐relevant setup: lamellae assembled on a substrate that strongly favors face‐on orientation, but exposed to a film surface that promotes orientation along an "easy" direction, other than face on. It is assumed that the face‐on order propagates from the substrate, but the lamellae bend to reduce their surface energy. A qualitative free‐energy model is developed. The deformation is investigated as a function of film thickness, effective Young modulus, anchoring coefficient, and easy direction at the free surface. The calculations highlight the importance of elastic constants – lamellae can substantially deform already when Young moduli are only an order of magnitude smaller than the values that are reported for crystals. Softer Young moduli are expected when lamellar assembly occurs in a non‐solidified mesophase that can be an equilibrium or (more speculatively) a transient state prior to crystallization. The alternative scenario of a two‐layered film is also evaluated, where edge‐on and face‐on grains form, respectively, at the free surface and substrate. [ABSTRACT FROM AUTHOR]

Non‐conjugated pendant electroactive polymers (NCPEPs) are an emerging class of polymers that offer the potential of combining the desirable optoelectronic properties of conjugated polymers with the superior synthetic methodologies and stability of traditional non‐conjugated polymers. Despite an increasing number of studies focused on NCPEPs, particularly on understanding fundamental structure‐property relationships, no attempts have been made to provide an overview on established relationships to date. This review showcases selected reports on NCPEP homopolymers and copolymers that demonstrate how optical, electronic, and physical properties of the polymers are affected by tuning of key structural variables such as the chemical structure of the polymer backbone, molecular weight, tacticity, spacer length, the nature of the pendant group, and in the case of copolymers the ratios between different comonomers and between individual polymer blocks. Correlation of structural features with improved π‐stacking and enhanced charge carrier mobility serve as the primary figures of merit in evaluating impact on NCPEP properties. While this review is not intended to serve as a comprehensive summary of all reports on tuning of structural parameters in NCPEPs, it highlights relevant established structure‐property relationships that can serve as a guideline for more targeted design of novel NCPEPs in the future. [ABSTRACT FROM AUTHOR]

Up to now, researches on the mobility–stretchability of semiconducting polymers are extensively investigated, but little attention was paid to their morphology and field‐effect transistor characteristics under compressive strains, which is equally crucial in wearable electronic applications. In this work, a contact film transfer method is applied to evaluate the mobility–compressibility properties of conjugated polymers. A series of isoindigo–bithiophene conjugated polymers with symmetric carbosilane side chains (P(SiSi)), siloxane‐terminated alkyl side chains (P(SiOSiO)), and combined asymmetric side chains (P(SiOSi)) are investigated. Accordingly, a compressed elastomer slab is used to transfer and compress the polymer films by releasing prestrain, and the morphology and mobility evolutions of these polymers are tracked. It is found that P(SiOSi) outperforms the other symmetric polymers including P(Si─Si) and P(SiO─SiO), having the ability to dissipate strain with its shortened lamellar spacing and orthogonal chain alignment. Notably, the mechanical durability of P(SiOSi) is also enhanced after consecutive compress–release cycles. In addition, the contact film transfer technique is demonstrated to be applicable to investigate the compressibility of different semiconducting polymers. These results demonstrate a comprehensive approach to understand the mobility–compressibility properties of semiconducting polymers under tensile and compressive strains. [ABSTRACT FROM AUTHOR]

As a monumental breakthrough in cancer treatment, immunotherapy has attracted tremendous attention in recent years. However, one challenge faced by immunotherapy is the low response rate and the immune‐related adverse events (irAEs). Therefore, it is important to explore new therapeutic strategies and platforms for boosting therapeutic benefits and decreasing the side effects of immunotherapy. In recent years, semiconducting polymer (SP), a category of organic materials with π‐conjugated aromatic backbone, has been attracting considerable attention because of their outstanding characteristics such as excellent photophysical features, good biosafety, adjustable chemical flexibility, easy fabrication, and high stability. With these distinct advantages, SP is extensively explored for bioimaging and photo‐ or ultrasound‐activated tumor therapy. Here, the recent advancements in SP‐based nanomedicines are summarized for enhanced tumor immunotherapy. According to the photophysical properties of SPs, the cancer immunotherapies enabled by SPs with the photothermal, photodynamic, or sonodynamic functions are highlighted in detail, with a particular focus on the construction of combination immunotherapy and activatable nanoplatforms to maximize the benefits of cancer immunotherapy. Herein, new guidance and comprehensive insights are provided for the design of SPs with desired photophysical properties to realize maximized effectiveness of required biomedical applications. [ABSTRACT FROM AUTHOR]

Two polyesteramides were synthesized via polycondensation reactions involving 4′-amino-4-hydroxychalcone 3a with succinic acid (4) and terephthalic acid (5), utilizing phosphoryl chloride as a chlorinating agent. A parallel reaction with (E)-1,3-bis(4-hydroxyphenyl) prop-2-en-1-one chalcone (3b) yielded two polyesters under identical conditions. The resultant polymers were obtained with excellent yields ranging from 93 % to 98 %. Characterization of the obtained polyesteramides and polyesters was conducted using various analytical techniques. Fourier-transform infrared spectroscopy (FTIR) evidenced the disappearance of the OH group's broad band from the initial monomers, providing strong support for polymer formation. Thermal gravimetric analysis (TGA) results indicated high thermal stability of all prepared polymers at elevated temperatures, designating them as potential thermoplastic polymers. Powder X-ray diffraction (XRD) outcomes demonstrated a significant amorphous nature for all synthesized polymers, with degrees ranging from 67.56 % to 74.75 %. Analysis of current/voltage (I-V) curves revealed a wide spectrum of electrical conductivity for polymers containing chalcone in their repeating units, ranging from negligibly low values of 0.08 µS/cm to 0.31 μS/cm, indicating their potential as semiconducting materials. Variations in conductivity across synthesized polymers were attributed to the degree of conjugation in polymeric chains and their crystallinity levels.

Fluorescence imaging in the second near-infrared (NIR-II) region has become one of the most powerful tools in clinical diagnosis and therapy assessment because of its high spatial resolution, rapid feedback, radiation safety, and low cost. Conjugated polymer nanoparticles (Pdots) based on donor-acceptor (D-A) polymers are some of the most promising fluorescent probes which have many superior characteristics, such as a high fluorescence brightness, good photostability, facile functionalization, and low cytotoxicity. While there has been tremendous progress in developing fluorescent polymers for use in the NIR-II wavelength range, the types of monomer structures used as building blocks for NIR-II fluorophores are still limited compared to those for organic solar cells and organic transistors. This review summarizes the NIR-II fluorescent polymers reported in the past few decades. The donor/acceptor unit structures of the polymers are systematically classified and discussed, which will provide new insights into the logical molecular design of donor/acceptor units for the development of high-brightness NIR-II Pdots. [ABSTRACT FROM AUTHOR]

Developing high‐performance but low‐cost n‐type polymers remains a significant challenge in the commercialization of organic field‐effect transistors (OFETs). To achieve this objective, it is essential to design the key electron‐deficient units with simple structures and facile preparation processes, which can facilitate the production of low‐cost n‐type polymers. Herein, by sequentially introducing fluorine and cyano functionalities onto trans‐1,3‐butadiene, we developed a series of structurally simple but highly electron‐deficient building blocks, namely 1,4‐dicyano‐butadiene (CNDE), 3‐fluoro‐1,4‐dicyano‐butadiene (CNFDE), and 2,3‐difluoro‐1,4‐dicyano‐butadiene (CNDFDE), featuring a highly coplanar backbone and deep‐positioned lowest unoccupied molecular orbital (LUMO) energy levels (−3.03–4.33 eV), which render them highly attractive for developing n‐type semiconducting polymers. Notably, all these electron‐deficient units can be easily accessed by a two‐step high‐yield synthetic procedure from low‐cost raw materials, thus rendering them highly promising candidates for commercial applications. Upon polymerization with diketopyrrolopyrrole (DPP), three copolymers were developed that demonstrated unipolar n‐type transport characteristics in OFETs with the highest electron mobility of >1 cm2 V−1 s−1. Hence, CNDE, CNFDE, and CNDFDE represent a class of novel, simple, and efficient electron‐deficient units for constructing low‐cost n‐type polymers, thereby providing valuable insight for OFET applications. [ABSTRACT FROM AUTHOR]

Recent work on non‐conjugated pendant electroactive polymers (NCPEPs) has demonstrated significant impacts of structural parameters such as backbone stereoregularity and the spacer connecting the pendant to the backbone on properties, most notably on charge carrier mobilities. Tuning of the pendant group however has not been reported for stereoregular NCPEPs. Here we present a family of novel isotactic poly((carbazolyl‐alkyl‐triazolyl)methyl methacrylates) (PCzATMMAs) for which the effects of increasing the pendant group from carbazole to 3,6‐bis(4‐(2‐ethylhexyl)thiophen‐2‐yl)‐carbazole were investigated. Based on unsuccessful post‐polymerization functionalization with this extended group via previously reported transesterification and thiol‐ene methodologies, we report functionalization via copper‐catalyzed azide‐alkyne cycloaddition which was demonstrated to be highly effective. The effect of spacer length was also investigated for comparison with previously established effects with alkyl spacers. Within the family of PCzATMMAs, hole mobilities were found to increase with longer spacer length and with thermal annealing. The incorporation of an extended pendant with alkyl solubilizing chains was found to result in a lower hole mobility than the equivalent polymer with an unfunctionalized pendant group. Importantly, the copper catalyzed azide‐alkyne cycloaddition proved to be an effective method of post‐polymerization functionalization for stereoregular NCPEPs when extending beyond a simple carbazole pendant. [ABSTRACT FROM AUTHOR]

For efficient colloidal quantum dot (CQD) solar cells (CQD‐SCs), thiol‐passivated p‐type CQDs are generally used as a hole‐transporting material (HTM); however, there are issues with the control of optoelectrical properties, low thiol passivation rate, and poor morphology with a power conversion efficiency (PCE) of approximately 11%. Although polymeric HTMs have been introduced to address these issues, maximizing efficiency and achieving green‐solvent processability and thermal stability for commercialization is necessary. Here, we synthesize a novel benzodifuran (BDF)‐based HTM (asy‐ranPBTBDF) showing an electron‐deficient state, low steric hindrance, and low planarity compared to those of a typical benzodithiophene (BDT)‐based HTM (asy‐ranPBTBDT). BDF properties lead to deep high occupied molecular orbital (HOMO) levels, close π–π stacking, excellent solubility, and amorphous properties related to efficiency, green‐solvent processability, and thermal stability. With these benefits, the asy‐ranPBTBDF‐based CQD‐SC showed enhanced open‐circuit voltage (VOC) (0.65 V) and PCE (13.29%) compared to those of the asy‐ranPBTBDT‐based device (0.63 V and 12.22%) in toxic processes with chlorobenzene. The asy‐ranPBTBDF‐based CQD‐SC showed a PCE of 12.51% in a green‐solvent process with 2‐methylanisole and improved thermal stability at 80 °C (83.8% retaining after 24 h) owing to less lateral crystallization than the asy‐ranPBTBDT‐based device (60.8% retaining after 24 h). [ABSTRACT FROM AUTHOR]

Carrier mobility in doped conjugated polymers is limited by Coulomb interactions with dopant counterions. This complicates studying the effect of the dopant's oxidation potential on carrier generation because different dopants have different Coulomb interactions with polarons on the polymer backbone. Here, dodecaborane (DDB)-based dopants are used, which electrostatically shield counterions from carriers and have tunable redox potentials at constant size and shape. DDB dopants produce mobile carriers due to spatial separation of the counterion, and those with greater energetic offsets produce more carriers. Neutron reflectometry indicates that dopant infiltration into conjugated polymer films is redox-potential-driven. Remarkably, X-ray scattering shows that despite their large 2-nm size, DDBs intercalate into the crystalline polymer lamellae like small molecules, indicating that this is the preferred location for dopants of any size. These findings elucidate why doping conjugated polymers usually produces integer, rather than partial charge transfer: dopant counterions effectively intercalate into the lamellae, far from the polarons on the polymer backbone. Finally, it is shown that the IR spectrum provides a simple way to determine polaron mobility. Overall, higher oxidation potentials lead to higher doping efficiencies, with values reaching 100% for driving forces sufficient to dope poorly crystalline regions of the film.

The therapeutic efficacy of photodynamic therapy is limited by the ability of light to penetrate tissues. Due to this limitation, Cerenkov luminescence (CL) from radionuclides has recently been proposed as an alternative light source in a strategy referred to as Cerenkov radiation‐induced therapy (CRIT). Semiconducting polymer nanoparticles (SPNs) have ideal optical properties, such as large absorption cross‐sections and broad absorbance, which can be utilized to harness the relatively weak CL produced by radionuclides. SPNs can be doped with photosensitizers and have ≈100% energy transfer efficiency by multiple energy transfer mechanisms. Herein, an optimized photosensitizer‐doped SPN is investigated as a nanosystem to harness and amplify CL for cancer theranostics. It is found that semiconducting polymers significantly amplify CL energy transfer efficiency. Bimodal positron emission tomography (PET) and optical imaging studies show high tumor uptake and retention of the optimized SPNs when administered intravenously or intratumorally. Lastly, it is found that photosensitizer‐doped SPNs have excellent potential as a cancer theranostics nanosystem in an in vivo tumor therapy study. This study shows that SPNs are ideally suited to harness and amplify CL for cancer theranostics, which may provide a significant advancement for CRIT that are unabated by tissue penetration limits. [ABSTRACT FROM AUTHOR]

Thiophenes functionalised in the 3‐position are ubiquitous building blocks for the design and synthesis of organic semiconductors. Their non‐centrosymmetric nature has long been used as a powerful synthetic design tool exemplified by the vastly different properties of regiorandom and regioregular poly(3‐hexylthiophene) owing to the repulsive head‐to‐head interactions between neighbouring side chains in the regiorandom polymer. The renewed interest in highly electron‐rich 3‐alkoxythiophene based polymers for bioelectronic applications opens up new considerations around the regiochemistry of these systems as both the head‐to‐tail and head‐to‐head couplings adopt near‐planar conformations due to attractive intramolecular S−O interactions. To understand how this increased flexibility in the molecular design can be used advantageously, we explore in detail the geometrical and electronic effects that influence the optical, electrochemical, structural, and electrical properties of a series of six polythiophene derivatives with varying regiochemistry and comonomer composition. We show how the interplay between conformational disorder, backbone coplanarity and polaron distribution affects the mixed ionic‐electronic conduction. Ultimately, we use these findings to identify a new conformationally restricted polythiophene derivative for p‐type accumulation‐mode organic electrochemical transistor applications with performance on par with state‐of‐the‐art mixed conductors evidenced by a μC* product of 267 F V−1 cm−1 s−1. [ABSTRACT FROM AUTHOR]

The interactions between counterions and electronic carriers in electrically doped semiconducting polymers are important for delocalization of charge carriers, electronic conductivity, and thermal stability. The introduction of a dianions in semiconducting polymers leads to double doping where there is one counterion for two charge carriers. Double doping minimizes structural distortions, but changes the electrostatic interactions between the carriers and counterions. Polymeric ionic liquids (PIL) with croconate dianions are helpful to investigate the role of the counterion in p‐type semiconducting polymers. PILs prevent diffusion of the cation into the semiconducting polymers during ion exchange. The redox‐active croconate dianions undergo ion exchange with doped semiconducting polymers depending on their ionization energy. Croconate dianions are found to reduce doped films of poly(3‐hexyl thiophene), but undergo ion exchange with a polythiophene with tetraethylene glycol side chains, P(g42T‐T), that has a lower ionization energy. The croconate dianion maintains crystalline order in P(g42T‐T) and leads to a lower activation energy for the electrical conductivity than PF6− counterions. The control of the doping level with croconate allows optimization of the thermoelectric performance of the semiconducting polymer. The thermal stability of the doped films of P(g42T‐T) is found to depend strongly on the nature of the counterion. [ABSTRACT FROM AUTHOR]

Semiconducting polymers are attractive optical materials in optoelectronic devices and biomedical applications because of their superior optical properties and remarkable versatility. Optical imaging in the second near‐infrared window (NIR‐II) has become increasingly popular owing to the merits of large penetration depth and high signal to noise ratio, leading to a great deal of interest in the exploration and development of optical probes in the NIR‐II region. In this review, recent advances in the development of semiconducting polymer nanoparticles (SPNs) in the NIR‐II region for biomedical imaging and therapeutics are summarized. This review focuses on the design strategies in semiconducting polymers toward enhancing their NIR‐II emission for deep tissue imaging, improving their performance in photoacoustic imaging, utilizing their large absorptivity for photothermal and photodynamic therapy, and a number of comprehensive applications for multifunctional imaging and optical therapeutics. Finally, the current challenges of semiconducting polymer probes are discussed and the perspectives on the future development in the field are shared. [ABSTRACT FROM AUTHOR]

One of the most effective ways to tune the electronic properties of conjugated polymers is to dope them with small-molecule oxidizing agents, creating holes on the polymer and molecular anions. Undesirably, strong electrostatic attraction from the anions of most dopants localizes the holes created on the polymer, reducing their mobility. Here, a new strategy utilizing a substituted boron cluster as a molecular dopant for conjugated polymers is employed. By designing the cluster to have a high redox potential and steric protection of the core-localized electron density, highly delocalized polarons with mobilities equivalent to films doped with no anions present are obtained. AC Hall effect measurements show that P3HT films doped with these boron clusters have conductivities and polaron mobilities roughly an order of magnitude higher than films doped with F4 TCNQ, even though the boron-cluster-doped films have poor crystallinity. Moreover, the number of free carriers approximately matches the number of boron clusters, yielding a doping efficiency of ≈100%. These results suggest that shielding the polaron from the anion is a critically important aspect for producing high carrier mobility, and that the high polymer crystallinity required with dopants such as F4 TCNQ is primarily to keep the counterions far from the polymer backbone.

Integrating the ultralong excitation wavelength, high extinction coefficient, and prominent photothermal conversion ability into a single photothermal agent is an appealing yet significantly challenging task. Herein, a precise dual‐acceptor engineering strategy is exploited for this attempt based on donor‐acceptor (D‐A) type semiconductor polymers by subtly regulating the molar proportions of the two employed electron acceptor moieties featuring different electronic affinity and π‐conjugation degrees, and making full use of the active intramolecular motion‐induced photothermal effect. The optimal polymer SP4 synchronously shows desirable second near‐infrared (NIR‐II) absorption, an extremely high extinction coefficient, and satisfactory photothermal conversion behavior. Consequently, the unprecedented performance of SP4 NPs on 1064 nm laser‐excited photoacoustic imaging (PAI)‐guided photothermal therapy (PTT) is demonstrated by the precise tumor diagnosis and complete tumor elimination. [ABSTRACT FROM AUTHOR]

When an electron is removed from a conjugated polymer, such as poly(3‐hexylthiophene‐2,5‐diyl) (P3HT), the remaining hole and associated change in the polymer backbone structure from aromatic to quinoidal are referred to as a polaron. Bipolarons are created by removing the unpaired electron from an already‐oxidized polymer segment. In electrochemically‐doped P3HT films, polarons, and bipolarons are readily observed, but in chemically‐doped P3HT films, bipolarons rarely form. This is explained by studying the effects of counterion position on the formation of polarons, strongly coupled polarons, and bipolarons using both spectroscopic and X‐ray diffraction experiments and time‐dependent density functional theory calculations. The counterion positions control whether two polarons spin‐pair to form a bipolaron or whether they strongly couple without spin‐pairing are found. When two counterions lie close to the same polymer segment, bipolarons can form, with an absorption spectrum that is blueshifted from that of a single polaron. Otherwise, polarons at high concentrations do not spin‐pair, but instead J‐couple, leading to a redshifted absorption spectrum. The counterion location needed for bipolaron formation is accompanied by a loss of polymer crystallinity. These results explain the observed formation order of single polarons, coupled single polarons, and singlet bipolarons in electrochemically‐ and chemically‐doped conjugated polymers. [ABSTRACT FROM AUTHOR]

Luminescent polymer nanomaterials not only have the characteristics of various types of luminescent functional materials and a wide range of applications, but also have the characteristics of good biocompatibility and easy functionalization of polymer nanomaterials. They are widely used in biomedical fields such as bioimaging, biosensing, and drug delivery. Designing and constructing new controllable synthesis methods for multifunctional fluorescent polymer nanomaterials with good water solubility and excellent biocompatibility is of great significance. Exploring efficient functionalization methods for luminescent materials is still one of the core issues in the design and development of new fluorescent materials. With this in mind, this review first introduces the structures, properties, and synthetic methods regarding fluorescent polymeric nanomaterials. Then, the functionalization strategies of fluorescent polymer nanomaterials are summarized. In addition, the research progress of multifunctional fluorescent polymer nanomaterials for bioimaging is also discussed. Finally, the synthesis, development, and application fields of fluorescent polymeric nanomaterials, as well as the challenges and opportunities of structure–property correlations, are comprehensively summarized and the corresponding perspectives are well illustrated. [ABSTRACT FROM AUTHOR]

Conjugated polymers are of great interest owing to their potential in stretchable electronics to function under complex deformation conditions. To improve the performance of conjugated polymers, various structural designs have been proposed and these conjugated polymers are specially applied in exotic optoelectronics. In this work, a series of all‐conjugated block copolymers (PII2T‐b‐PNDI2T) comprising poly(isoindigo–bithiophene) (PII2T) and poly(naphthalenediimide–bithiophene) (PNDI2T) are developed with varied compositions and applied to electret‐free phototransistor memory. Accordingly, these memory devices present p‐type transport capability and electrical‐ON/photo‐OFF memory behavior. The efficacy of the all‐conjugated block copolymer design in improving the memory‒photoresponse properties in phototransistor memory is revealed. By optimizing the composition of the block copolymer, the corresponding device achieves a wide memory window of 36 V and a high memory ratio of 7 × 104. Collectively, the results of this study indicate a new concept for designing electret‐free phototransistor memory by using all‐conjugated block copolymer heterojunctions to mitigate the phase separation of conjugated polymer blends. Meanwhile, the intrinsic optoelectronic properties of the constituent conjugated polymers can be well‐maintained by using an all‐conjugated block copolymer design. [ABSTRACT FROM AUTHOR]

The orientational control of semiconducting polymers (SCPs) in floating films offers several advantages over conventional solution‐processing methods for device fabrication, and the unidirectional floating film transfer method (UFTM) has been applied to fabricate large‐area oriented p‐type SCP films. Here, UFTM can be used to prepare high‐performance n‐type SCP films of P(NDI2OD‐T2) is reported. A strong correlation between the degree of polymer orientation and the solvent used for the preparation of P(NDI2OD‐T2) floating films is observed. In particular, the size of the nanofibers aligned along the orientation direction prepared using chloroform is dramatically increased by adding a small amount of chlorobenzene. Microstructural characterization reveals that the P(NDI2OD‐T2) floating films are uniaxially aligned with edge‐on orientation, whereas the spin‐coated films are isotropic with face‐on orientation. Notably, the floating films of P(NDI2OD‐T2) prepared with solvent blending have higher electron mobility with ambipolar‐like device characteristics and high threshold voltage (VTH) of ≈25 V. Finally, using the one‐step immersion process, the introduction of an interlayer of hexa(ethylene glycol)‐dithiol between the source/drain contacts and P(NDI2OD‐T2) film results in a drastic improvement in device, giving unipolar n‐channel transistor characteristics with a VTH of ≈0 V, on/off ratio of >105, and mobility reliability factor of almost 100%. [ABSTRACT FROM AUTHOR]

In recent years, semiconducting polymer dots (Pdots) have attracted much attention due to their excellent photophysical properties and applicability, such as large absorption cross section, high brightness, tunable fluorescence emission, excellent photostability, good biocompatibility, facile modification and regulation. Therefore, Pdots have been widely used in various types of sensing and imaging in biological medicine. More importantly, the recent development of Pdots for point-of-care biosensing and in vivo imaging has emerged as a promising class of optical diagnostic technologies for clinical applications. In this review, we briefly outline strategies for the preparation and modification of Pdots and summarize the recent progress in the development of Pdots-based optical probes for analytical detection and biomedical imaging. Finally, challenges and future developments of Pdots for biomedical applications are given. [ABSTRACT FROM AUTHOR]

The electronic properties of conjugated polymers depend sensitively on their conformation and morphology. However, control over the morphology of conjugated polymers is highly challenging. Here, we demonstrate a facile approach for assembling conjugated polymers into anisotropic nanostructures. In a water–tetrahydrofuran (H2O–THF) binary solvent, we prepared ellipsoidal nanoparticles, which can subsequently self‐assemble into triangle‐ring and rod‐like nanostructures in a stepwise manner. The transitions among these morphologies can be rationally regulated by tuning the volume ratio of H2O to THF and the polymer concentration. The nanostructures show shape‐dependent absorption from 383 to 403 nm and significant fluorescence enhancement with a quantum yield up to 70%. The oxetane groups in the polymer side chains and the presence of surfactant in the solvent are decisive for the anisotropic assembly. We further demonstrate multicolor fluorescent nanowires with good structural integrity over doping of dye molecules or other fluorescent polymers. Single nanowires were characterized by high‐order super‐resolution optical fluctuation imaging, which revealed spatial distribution of the photooxidation sites along single nanowire for easily generating hole polarons. [ABSTRACT FROM AUTHOR]

Abstract The orientational control of semiconducting polymers (SCPs) in floating films offers several advantages over conventional solution‐processing methods for device fabrication, and the unidirectional floating film transfer method (UFTM) has been applied to fabricate large‐area oriented p‐type SCP films. Here, UFTM can be used to prepare high‐performance n‐type SCP films of P(NDI2OD‐T2) is reported. A strong correlation between the degree of polymer orientation and the solvent used for the preparation of P(NDI2OD‐T2) floating films is observed. In particular, the size of the nanofibers aligned along the orientation direction prepared using chloroform is dramatically increased by adding a small amount of chlorobenzene. Microstructural characterization reveals that the P(NDI2OD‐T2) floating films are uniaxially aligned with edge‐on orientation, whereas the spin‐coated films are isotropic with face‐on orientation. Notably, the floating films of P(NDI2OD‐T2) prepared with solvent blending have higher electron mobility with ambipolar‐like device characteristics and high threshold voltage (VTH) of ≈25 V. Finally, using the one‐step immersion process, the introduction of an interlayer of hexa(ethylene glycol)‐dithiol between the source/drain contacts and P(NDI2OD‐T2) film results in a drastic improvement in device, giving unipolar n‐channel transistor characteristics with a VTH of ≈0 V, on/off ratio of >105, and mobility reliability factor of almost 100%.

Abstract Crosslinking is a ubiquitous strategy in polymer engineering to increase the thermomechanical robustness of solid polymers but has been relatively unexplored in the context of π‐conjugated (semiconducting) polymers. Notwithstanding, mechanical stability is key to many envisioned applications of organic electronic devices. For example, the wide‐scale distribution of photovoltaic devices incorporating conjugated polymers may depend on integration with substrates subject to mechanical insult—for example, road surfaces, flooring tiles, and vehicle paint. Here, a four‐armed azide‐based crosslinker (“4Bx”) is used to modify the mechanical properties of a library of semiconducting polymers. Three polymers used in bulk heterojunction solar cells (donors J51 and PTB7‐Th, and acceptor N2200) are selected for detailed investigation. In doing so, it is shown that low loadings of 4Bx can be used to increase the strength (up to 30%), toughness (up to 75%), hardness (up to 25%), and cohesion of crosslinked films. Likewise, crosslinked films show greater physical stability in comparison to non‐crosslinked counterparts (20% vs 90% volume lost after sonication). Finally, the locked‐in morphologies and increased mechanical robustness enable crosslinked solar cells to have greater survivability to four degradation tests: abrasion (using a sponge), direct exposure to chloroform, thermal aging, and accelerated degradation (heat, moisture, and oxygen).

Abstract The electronic properties of conjugated polymers depend sensitively on their conformation and morphology. However, control over the morphology of conjugated polymers is highly challenging. Here, we demonstrate a facile approach for assembling conjugated polymers into anisotropic nanostructures. In a water–tetrahydrofuran (H2O–THF) binary solvent, we prepared ellipsoidal nanoparticles, which can subsequently self‐assemble into triangle‐ring and rod‐like nanostructures in a stepwise manner. The transitions among these morphologies can be rationally regulated by tuning the volume ratio of H2O to THF and the polymer concentration. The nanostructures show shape‐dependent absorption from 383 to 403 nm and significant fluorescence enhancement with a quantum yield up to 70%. The oxetane groups in the polymer side chains and the presence of surfactant in the solvent are decisive for the anisotropic assembly. We further demonstrate multicolor fluorescent nanowires with good structural integrity over doping of dye molecules or other fluorescent polymers. Single nanowires were characterized by high‐order super‐resolution optical fluctuation imaging, which revealed spatial distribution of the photooxidation sites along single nanowire for easily generating hole polarons.

Quantifying contributions to thermal conductivity from electrons and atomic vibrations in doped semiconducting polymers is important for heat transfer. Several studies report Lorenz numbers (L) that are larger than the Sommerfeld limit (L0), counterintuitively implying that charge carriers in semiconducting polymers carry more heat than those in metals. Alternatively, this phenomenon can be explained by recognizing that semiconducting polymers often contain insulating and conducting domains. Microstructures can lead to misinterpretation of the effective Lorenz number (Leff) observed macroscopically. Herein, effective medium theory (EMT) shows that inhomogeneity can result in macroscopic measurements where Leff ≠ L0, even when each component exhibits L0 at the microscopic level. The authors then extend the semi‐localized transport (SLoT) model to explain the origins of the large Leff values, validating with the prototypical poly(3,4‐ethylenedioxythiophene) system. This electro‐thermal extension of the SLoT model (ET‐SLoT) improves the ability to engineer the electronic contribution to thermal conductivity of semiconducting polymers. [ABSTRACT FROM AUTHOR]

Second near‐infrared window (NIR‐II, 1000−1700 nm) fluorescence imaging (FI) in phototheranostics benefits from deep tissue penetration, negligible body spontaneous fluorescence, exceptional spatiotemporal resolution, and diversified imaging agents. Inorganic and metal nanomaterials with NIR‐II emission are widely explored for NIR‐II FI, however, the concern about their intrinsic long‐term toxicity hampers further clinic applications. By contrast, whole organic NIR‐II FI agents, in particular, organic semiconducting molecules derived from large π‐conjugated molecular architectures and biologically amicable ingredients, owning inert photophysical potencies, tunable optical properties, and favorable biocompatibility, have the potential to be degraded and excreted from the body in molecular level. In this review, the development of NIR‐II fluorescence‐emitting organic semiconducting nanoplatforms, with a focus on their theranostic applications in biomedicine is discussed. The recent advances in the molecular design of semiconducting NIR‐II emitting agents for improving the properties of NIR‐II photonics (e.g., emission intensity, quantum yield, emission wavelength, and activatable emission) and optimizing disease phototheranostics (the synergistic combination of NIR‐II FI‐based diagnosis and photo‐related therapeutic methods) are highlighted. Finally, the challenges and perspectives to building high‐powered new‐generation organic semiconducting nanoplatforms for NIR‐II phototheranostics of a variety of diseases are discussed. [ABSTRACT FROM AUTHOR]