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An open‐shell quinoidal conjugated polymer exhibiting n‐type semiconducting behavior is successfully synthesized and characterized. An electron‐deficient azaaromatic unit is proven to reduce the energy levels of frontier orbitals via the electronegative nitrogen atom and steric hindrance within the polymer backbone. A synthesized azaquinoidal bithiophene (azaQuBT) is a quinoidal bithiophene that is end‐functionalized with a pyridine ring. The open‐shell quinodial conjugated polymer, poly(azaquinoidal bithiophene‐thiophene), PazaQuBT‐T, is synthesized using azaQuBT and thiophene. The extended quinoidal building block, which has an open‐shell diradical character, induces low bandgaps, redox amphoterism, and high‐spin‐induced paramagnetic behavior of the resulting polymer. PazaQuBT‐T achieves ambipolar charge‐transport behavior in organic field‐effect transistor (OFET) devices. Through a PEIE treatment onto the contact electrode, PazaQuBT‐based OFETs exhibit unipolar n‐channel operation with electron mobility up to 0.98 cm2 V−1 s−1. This work demonstrates the development of novel open‐shell conjugated polymers with high‐spin characteristics and n‐type semiconducting property. An open‐shell quinoidal conjugated polymer, named as PazaQuBT‐T, is synthesized and characterized. The open‐shell polymer exhibits high spin characteristics resulting from the open‐shell diradical character of an azaquinoid building block. The organic field‐effect transistor (OFET) devices based on PazaQuBT‐T as an active layer demonstrate n‐channel operation with maximum electron mobility of 0.98 cm2 V−1 s−1.

In recent years, conjugated polymers have attracted great attention in the application as photovoltaic donor materials in polymer solar cells （PSCs）. Broad absorption, lower-energy bandgap, higher hole mobility, relatively lower HOMO energy levels, and higher solubility are important for the conjugated polymer donor materials to achieve high photovoltaic performance. Side-chain engineering plays a very important role in optimizing the physicochemical properties of the conjugated polymers. In this article, we review recent progress on the side-chain engineering of conjugated polymer donor materials, including the optimization of flexible side-chains for balancing solubility and intermolecular packing （aggregation）, electron-withdrawing substituents for lowering HOMO energy levels, and two-dimension （2D）-conjugated polymers with conjugated side-chains for broadening absorption and enhancing hole mobility. After the molecular structural optimization by side-chain engineering, the 2D-conjugated polymers based on benzodithiophene units demonstrated the best photovoltaic performance, with powerconversion efficiency higher than 9%.

Donor–acceptor (D‐A) conjugated polymers have demonstrated great potential in organic field‐effect transistors application, and their aggregated structure is a crucial factor for high charge mobility. However, the aggregated structure of D‐A conjugated polymer films is complex and the structure–property relationship is difficult to understand. This review provides an overview of recent progress in controlling the aggregated structure of D‐A conjugated polymer films for higher mobility, including the mechanisms, methods, and properties. We first discuss the multilevel microstructures of D‐A conjugated polymer films, and then summarize the current understanding of the relationship between film microstructures and charge transport properties. Subsequently, we review the theory of D‐A conjugated polymer crystallization. After that, we summarize the common methods to control the aggregated structure of semi‐crystalline and near‐amorphous D‐A conjugated polymer films, such as crystallites and aggregates, tie chains, film alignment, and attempt to understand them from the basic theory of polymer crystallization. Finally, we provide the current challenges in controlling the aggregated structure of D‐A conjugated polymer films and in understanding the structure–property relationship. Donor‐acceptor (D‐A) conjugated polymers have demonstrated great potential in organic field‐effect transistors (OFETs) application, and their aggregated structure is a crucial factor for high charge mobility. This review provides an overview of recent progress in controlling the aggregated structure of semi‐crystalline and near‐amorphous D‐A conjugated polymers, including crystallization theories, control methods, aggregated structures, and charge mobilities.

Antibody‐drug conjugates are a cutting‐edge biotechnology recently attracting wide attention in the medical field. Binding antibodies to drug molecules could deliver drugs precisely to the site of the lesion, which shows great potential in the treatment of tumors and immune diseases. In this paper, we outlined the current popular antibody‐coupling techniques and summarized various common antibody‐coupling techniques, including antibody‐coupled small toxic molecules, antibody‐coupled oligenucleotides, antibody‐coupled cells, and antibody‐coupled polymers. It provided a new therapeutic strategy and means for targeted drug delivery technology. Finally, we discussed the challenges and future development of the antibody‐drug conjugates.

The photocatalytic synthesis of hydrogen peroxide (H2O2) at room temperature has garnered significant attention as an environmentally friendly alternative to traditional anthraquinone oxidation processes. However, the low exciton dissociation efficiency at room temperature often hinders photocatalytic performance. In this study, it is demonstrated that tuning the substitution sites of electron donors in Donor‐Acceptor (D‐A) conjugated polymers can significantly enhance exciton dissociation by reducing exciton activation energy, which facilitates the spontaneous separation of excitons at room temperature. For comparison, materials with exciton separation energies ≈89 meV exhibit a hydrogen peroxide production rate of 2692 µmol·g−1·h−1. In contrast, the main material developed in this work, O‐PTAQ, demonstrates a substantially lower exciton separation energy of 22 meV, resulting in a hydrogen peroxide production rate of 4989 µmol·g−1·h−1 under ambient conditions, outperforming most reported organic semiconductors. This enhancement is attributed to the increased electron delocalization in the electron donors, which lowers exciton activation energy to promote efficient exciton separation. The findings highlight the critical role of molecular‐level structural tuning in enhancing exciton dissociation, providing a promising strategy for the development of high‐efficiency photocatalysts for sustainable H2O2 production. This study identifies that replacing electron‐donating units at different positions enhances the delocalization of the electron cloud in the electron donors, which in turn increases the delocalization of the overall material. The exciton activation energy is effectively reduced, promoting the spontaneous dissociation of excitons at room temperature and enabling highly efficient photocatalytic synthesis of H2O2.

Conjugated polymer (CP)-based photothermal materials have been widely acknowledged as a promising class of photothermal agents for biomedical applications. This is because of their light-harvesting ability, photothermal conversion efficiency, photostability, and favorable biocompatibility. Donor-acceptor (D-A) CPs, which are based on the evolution of CPs, have attracted considerable interest in this field because of their tunable absorption in the near-infrared biological window. This property enables their deep penetration into cancer sites, improving the efficiency of anti-cancer treatment. This review mainly focuses on the potential of D-A CP to achieve improved and efficient photothermal conversion, exploring its optimized advantages for photothermal therapy applications. Based on the general insight provided by the Jablonski diagram, the mechanism and related principles for activating photothermal conversion in CPs and D-A CP are proposed and discussed. This provides an overall understanding of the correlation between molecular CP nanomaterials and heat generation. This review presents the details of methodologies for the rational design of CP nanoparticles with efficient photothermal conversion ability, thus facilitating the use of CPs in biomedical diagnostic and therapeutic applications. Photothermal conversion mechanism of organic materials and influencing elements based on Jablonski's diagram. Enhanced approaches for photothermal conversion of conjugated polymer nanoparticles. Improved methodologies in photothermal conversion of donor-acceptor conjugated polymer nanoparticles. Potential and future direction of donor-acceptor conjugated polymer development in photothermal therapy and biomedical applications.

π‐Conjugated polymers including polythiophenes are emerging as promising electrode materials for (photo)electrochemical reactions, such as water reduction to H2 production and oxygen (O2) reduction to hydrogen peroxide (H2O2) production. In the current work, a copolymer of phenylene and thiophene is designed, where the phenylene ring lowers the highest occupied molecular orbital level of the polymer of visible‐light‐harvesting thiophene entities and works as a robust catalytic site for the O2 reduction to H2O2 production. The very high onset potential of the copolymer for O2 reduction (+1.53 V vs RHE, pH 12) allows a H2O2 production setup with a traditional water‐oxidation catalyst, manganese oxide (MnOx), as the anode. MnOx is deposited on one face of a conducting plate, and visible‐light illumination of the copolymer layer formed on the other face aids steady O2 reduction to H2O2 with no bias assistance and a complete photocatalytic conversion rate of 14 000 mg (H2O2) gphotocat−1 h−1 or ≈0.2 mg (H2O2) cm−2 h−1. Metal‐free copolymer of phenylene and thiophene (PPT) works as a visible‐light‐harvester and highly selective and robust catalyst for the oxygen reduction to hydrogen peroxide (H2O2). Visible‐light‐illuminated PPT layer in combination with a manganese oxide (MnOx) catalyst exhibits the steady H2O2 production without bias voltage at pH 12 and with a very high gravimetric photocatalytic conversion rate of 14 000 mg (H2O2) gphotocat−1.

n‐Type organic electrochemical transistors (OECTs) and organic field‐effect transistors (OFETs) are less developed than their p‐type counterparts. Herein, polynaphthalenediimide (PNDI)‐based copolymers bearing novel fluorinated selenophene‐vinylene‐selenophene (FSVS) units as efficient materials for both n‐type OECTs and n‐type OFETs are reported. The PNDI polymers with oligo(ethylene glycol) (EG7) side chains P(NDIEG7‐FSVS), affords a high µC* of > 0.2 F cm−1 V−1 s−1, outperforming the benchmark n‐type Pg4NDI‐T2 and Pg4NDI‐gT2 by two orders of magnitude. The deep‐lying LUMO of −4.63 eV endows P(NDIEG7‐FSVS) with an ultra‐low threshold voltage of 0.16 V. Moreover, the conjugated polymer with octyldodecyl (OD) side chains P(NDIOD‐FSVS) exhibits a surprisingly low energetic disorder with an Urbach energy of 36 meV and an ultra‐low activation energy of 39 meV, resulting in high electron mobility of up to 0.32 cm2 V−1 s−1 in n‐type OFETs. These results demonstrate the great potential for simultaneously achieving a lower LUMO and a tighter intermolecular packing for the next‐generation efficient n‐type organic electronics. Novel PNDI‐based polymers bearing fluorinated selenophene‐vinylene‐selenophene (FSVS) are synthesized. The glycolated P(NDIEG7‐FSVS) with a deep‐lying LUMO of −4.63 eV gives an ultra‐low threshold voltage of 0.16 V, yielding a µC* > 0.2 F cm−1 V−1 s−1 in n‐type OECTs; the alkylated P(NDIOD‐FSVS), with a low Urbach energy of 36 meV and a low activation energy of 39 meV, exhibits electron mobility of > 0.3 cm2 V−1 s−1 in n‐type OFETs.

We used steady-state photoinduced absorption (PA), excitation dependence (EXPA(ω)) spectrum of the triplet exciton PA band, and its magneto-PA (MPA(B)) response to investigate singlet fission (SF) of hot excitons into two separated triplet excitons, in two luminescent and non-luminescent π-conjugated polymers. From the high energy step in the triplet EXPA(ω) spectrum of the luminescent polymer poly(dioctyloxy)phenylenevinylene (DOO-PPV) films, we identified a hot-exciton SF (HE-SF) process having threshold energy at E 2ET (=2.8 eV, where ET is the energy of the lowest lying triplet exciton), which is about 0.8 eV above the lowest singlet exciton energy. The HE-SF process was confirmed by the triplet MPA(B) response for excitation at E>2ET, which shows typical SF response. This process is missing in DOO-PPV solution, showing that it is predominantly interchain in nature. By contrast, the triplet EXPA(ω) spectrum in the non-luminescent polymer polydiacetylene (PDA) is flat with an onset at E=Eg ( 2.25 eV). From this, we infer that intrachain SF that involves a triplet-triplet pair state, also known as the 'dark' 2Ag exciton, dominates the triplet photogeneration in PDA polymer as Eg>2ET. The intrachain SF process was also identified from the MPA(B) response of the triplet PA band in PDA. Our work shows that the SF process in π-conjugated polymers is a much more general process than thought previously.

Flexible and mechanically robust gas sensors are the key technologies for wearable and implantable electronics. Herein, the authors demonstrate the high‐performance, flexible nitrogen dioxide (NO2) chemiresistors using a series of n‐type conjugated polymers (CPs: PNDIT2/IM‐x) and a polymer dopant (poly(ethyleneimine), PEI). Imine double bonds (C = N) are incorporated into the backbones of the CPs with different imine contents (x) to facilitate strong and selective interactions with NO2. The PEI provides doping stability, enhanced electrical conductivity, and flexibility. As a result, the NO2 sensors with PNDIT2/IM‐0.1 and PEI (1:1 by weight ratio) exhibit outstanding sensing performances, such as excellent sensitivity (ΔR/Rb = 240% @ 1 ppm), ultralow detection limit (0.1 ppm), high selectivity (ΔR/Rb < 8% @ 1 ppm of interfering analytes), and high stability, thereby outperforming other state‐of‐the‐art CP‐based chemiresistors. Furthermore, the thin film of PNDIT2/IM‐0.1 and PEI blend is stretchable and mechanically robust, providing excellent flexibility to the NO2 sensors. Our study contributes to the rational design of high‐performance flexible gas sensors. In this study, a high‐performance flexible NO2 chemiresistor (IM‐x/P‐y) is developed based on n‐type conjugated polymers containing imine bonds in the backbone. Excellent overall sensing performances with ultralow limit of detection (LOD) are demonstrated.