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Abstract In the development of high‐performance organic thermoelectric devices, n‐type materials, especially with small molecule semiconductors, lags far behind p‐type materials. In this paper, three small molecules are synthesized based on electron‐deficient naphthalene bis‐isatin building blocks bearing different alkyl chains with the terminal functionalized with 3‐ethylrhodanine unit and studied their aggregation and doping mechanism in detail. It is found that crystallinity plays an essential role in tuning the doping behavior of small molecules. Molecules with too strong crystallinity tend to aggregate with each other to form large crystalline domains, which cause significant performance degradation. While molecules with weak crystallinity can tolerate more dopants, most of them exhibit low mobility. By tuning the crystallinity carefully, organic thermoelectric devices based on C12NR can maintain high mobility and realize effective doping simultaneously, and a high power factor of 1.07 µW m−1 K−2 at 100 °C is realized. This delicate molecular design by modulating crystallinity provides a new avenue for realizing high‐performance organic thermoelectric devices.

Docetaxel (DTX) is one of the most promising chemotherapeutic agents for a variety of solid tumors. However, the clinical efficacy of the marketed formulation, Taxotere®, is limited due to its poor aqueous solubility, side effects caused by the emulsifier, and low selective DTX distribution in vivo. Here a facile, well-defined, and easy-to-scale up DTX-loaded N-(tert-butoxycarbonyl)-L-phenylalanine end-capped methoxy-poly(ethylene glycol)-block-poly(D,L-lactide) (mPEG-b-PLA-Phe(Boc)) micelles (DTX-PMs) were prepared in an effort to develop a less toxic and more efficacious docetaxel formulation. The physicochemical properties, pharmacokinetics, biodistribution, and in vivo anti-tumor efficacy were evaluated in comparison to the marketed DTX formulation Taxotere®. DTX was successfully encapsulated in the hydrophobic micellar core with a high encapsulation efficiency (> 95%) and a high drug loading capacity (4.81 ± 0.08%). DTX-PMs exhibited outstanding stability in the aqueous environment due to the strong interactions between the terminal amino acid residues and docetaxel. The pharmacokinetic study in Sprague–Dawley rats revealed higher DTX concentrations in both whole blood and plasma for the group treated with DTX-PMs than that treated with Taxotere® due to the improved stability of the micellar formulation. In human non-small cell lung cancer (A549) tumor-bearing Balb/c nude mice, DTX-PMs significantly improved DTX accumulation and stalled DTX elimination in tumors than in bone marrow. Furthermore, only by half of the DTX dosage, our DTX/mPEG-b-PLA-Phe(Boc) micelles can achieve similar therapeutic effects as Taxotere®. Altogether, DTX-PMs hold great promise as a simple and effective drug delivery system for cancer chemotherapy.

Organic electrochemical transistor (OECT)-based inverter introduces new prospects for energy-efficient brain-inspired artificial intelligence devices. Here, we report single-component OECT-based inverters by incorporating ambipolar p(gDPP-V). Notably, p(gDPP-V) shows state-of-the-art ambipolar OECT performances in both conventional (p/n-type mode transconductance of 29/25 S cm-1) and vertical (transconductance of 297.2/292.4 μS μm-2 under p/n operation) device architectures. Especially, the resulting highly stable vertical OECT-based inverter shows a high voltage gain of 105 V V-1 under a low driving voltage of 0.8 V. The inverter exhibits undiscovered voltage-regulated dual mode: volatile receptor and nonvolatile synapse. Moreover, applications of physiology signal recording and demonstrations of NAND/NOR logic circuits are investigated within the volatile feature, while neuromorphic simulations with a convolutional neural network and image memorizing capabilities are explored under the nonvolatile behavior. The ambipolar OECT-based inverter, capable of both volatile and nonvolatile operations, provides possibilities for the applications of reconfigurable complementary logic circuits in novel neuromorphic computing paradigms. [ABSTRACT FROM AUTHOR]

The ion/chemical‐based modulation feature of organic mixed ionic‐electronic conductors (OMIECs) are critical to advancing next generation bio‐integrated neuromorphic hardware. Despite achievements with polymeric OMIECs in organic electrochemical neuronal synapse (OENS). However, small molecule OMIECs based OENS has not yet been realized. Here, for the first time, we demonstrate an effective materials design concept of combining n‐type fused all‐acceptor small molecule OMIECs with subtle side chain optimization that enables robustly and flexibly modulating versatile synaptic behavior and sensing neurotransmitter in solid or aqueous electrolyte, operating in accumulation modes. By judicious tuning the ending side chains, the linear oligoether and butyl chain derivative gNR‐Bu exhibits higher recognition accuracy for a model artificial neural network (ANN) simulation, higher steady conductance states and more outstanding ambient stability, which is superior to the state‐of‐art n‐type OMIECs based OENS. These superior artificial synapse characteristics of gNR‐Bu can be attributed to its higher crystallinity with stronger ion bonding capacities. More impressively, we unprecedentedly realized n‐type small‐molecule OMIECs based OENS as a neuromorphic biosensor enabling to respond synaptic communication signals of dopamine even at sub‐μM level in aqueous electrolyte. This work may open a new path of small‐molecule ion‐electron conductors for next‐generation ANN and bioelectronics. [ABSTRACT FROM AUTHOR]

Aldol condensation is a cost‐effective and sustainable synthetic method, offering the advantages of low complexity, substrate universality, and high efficiency. Over the past decade, it has become popular for creating next‐generation organic functional materials, particularly rigid‐rod conjugated (semi)conductors. This review focuses on conjugated small molecules, oligomers, and polymeric (semi)conductors synthesized through aldol condensation, with emphasis on their remarkable features in advancing n‐type organic field‐effect transistors (OFETs), organic electrochemical transistors (OECTs), organic photovoltaics (OPVs), and organic thermoelectrics (OTEs) as well as NIR‐II photothermal conversion. Coherence character, optical properties, microstructure, and chain conformation are investigated to understand material‐property relationships. Future applications and challenges in this area are also discussed. [ABSTRACT FROM AUTHOR]

Currently, n‐type small‐molecule mixed ionic‐electronic conductors remain less explored and their molecular design rules are not mature enough. Herein, two n‐type glycolated imide‐fused polycyclic aromatic hydrocarbons (IPAHs), d‐gdiPDI and t‐gdiPDI, are developed to probe the effects of molecular conformation on the electronic, electrochemical, morphological, and coupled ionic‐electronic transport properties. It is found that the highly twisted scaffold in d‐gdiPDI, compared to the nearly planar one of t‐gdiPDI, has a strong positive effect on the charge storage properties and thus the performance of organic electrochemical transistors (OECTs). d‐gdiPDI exhibits a volumetric capacitance of 657 F cm−3, obviously outperforming that of t‐gdiPDI (261 F cm−3), which is the highest value reported to date for small‐molecule OECT materials. Moreover, a high charge‐storage capacity of up to 479 F g−1 is observed for d‐gdiPDI. Arising from such high ionic‐electronic coupling characteristic, d‐gdiPDI‐based OECTs present a ≈2 × times higher geometry‐normalized transconductance (gm,norm) of 105.3 mS cm−1 relative to that of t‐gdiPDI counterparts. Significantly, further application of d‐gdiPDI in solid‐electrolyte OECTs delivers a gm,norm of 142.4 mS cm−1. These findings indicate that IPAHs are very promising candidates for n‐type small‐molecule OECTs and highlight the superiority of twisting conformation manipulation in materials design toward high‐performance electrochemical devices. [ABSTRACT FROM AUTHOR]

In the development of high‐performance organic thermoelectric devices, n‐type materials, especially with small molecule semiconductors, lags far behind p‐type materials. In this paper, three small molecules are synthesized based on electron‐deficient naphthalene bis‐isatin building blocks bearing different alkyl chains with the terminal functionalized with 3‐ethylrhodanine unit and studied their aggregation and doping mechanism in detail. It is found that crystallinity plays an essential role in tuning the doping behavior of small molecules. Molecules with too strong crystallinity tend to aggregate with each other to form large crystalline domains, which cause significant performance degradation. While molecules with weak crystallinity can tolerate more dopants, most of them exhibit low mobility. By tuning the crystallinity carefully, organic thermoelectric devices based on C12NR can maintain high mobility and realize effective doping simultaneously, and a high power factor of 1.07 µW m−1 K−2 at 100 °C is realized. This delicate molecular design by modulating crystallinity provides a new avenue for realizing high‐performance organic thermoelectric devices. [ABSTRACT FROM AUTHOR]

The primary challenge for n‐type small‐molecule organic electrochemical transistors (OECTs) is to improve their electron mobilities and thus the key figure of merit μC*. Nevertheless, few reports in OECTs have specially proposed to address this issue. Herein, we report a 10‐ring‐fused polycyclic π‐system consisting of the core of naphthalene bis‐isatin dimer and the terminal moieties of rhodanine, which features intramolecular noncovalent interactions, high π‐delocalization and strong electron‐deficient characteristics. We find that this extended π‐conjugated system using the ring fusion strategy displays improved electron mobilities up to 0.043 cm2 V−1 s−1 compared to our previously reported small molecule gNR, and thereby leads to a remarkable μC* of 10.3 F cm−1 V−1 s−1 in n‐type OECTs, which is the highest value reported to date for small‐molecule OECTs. This work highlights the importance of π‐conjugation extension in polycyclic‐fused molecules for enhancing the performance of n‐type small‐molecule OECTs. [ABSTRACT FROM AUTHOR]

Highly efficient mixed ionic and electronic conduction is critical to developing high‐performance organic electrochemical transistors (OECTs) devices. While currently, the n‐type small molecules mixed conductors design strategy remains extremely lacking. Herein, ethylene glycol (EG) chain substituted electron‐deficient naphthalene bis‐isatin and rhodanine acceptor units with easily accessible steps are rationally fused, affording fused and planar novel semiconductors with weak intramolecular S–O 'conformation locks', where gNR with EG side chain and hgNR with hybrid alkyl‐EG side chain. The rigid, planar and highly electron‐deficient skeleton enables the resulting small molecule semiconductors to be efficient mixed ionic‐electronic conductors with very high OECT electron mobility up to 0.01 cm2 V−1 s−1. Remarkedly, gNR displays the record value of geometry‐normalized transconductance of 0.4 S cm−1 and μC* of 2.6 F V−1 cm−1 s−1, which can also be compared with the state‐of‐art n‐type semiconducting polymers in OECTs. Moreover, the effect of the alkyl spacer on the n‐type mixed ionic and electronic conduction features of the small molecule materials is investigated. The fused electron‐deficient acceptor‐acceptor (A–A) system with intramolecular conformation lock design strategy in this work provides a new avenue to realize next‐generation high‐performance small molecule mixed ionic and electronic conductors for OECT materials. [ABSTRACT FROM AUTHOR]

In this work, three n‐type donor–acceptor copolymers consisting of glycolated naphthalene tetracarboxylicdiimide (gNDI) coupled with variable donating companion moieties are reported. Using 2,2′‐bis(3,4‐ethylenedioxy)bithiophene, 2,​2′‐​bithiophene, 3,3′‐difluoro‐2,2′‐bithiophene (FBT), the donating strength of the donor units is systematically functionalized. These copolymers are used as a platform for aqueous‐based electrochemical devices, including energy‐storage devices, electrochromic devices (ECDs), and organic electrochemical transistors (OECTs). It is found that the electrochemical redox stability and electron mobility of copolymers are significantly improved via weakening the electron‐donating strength of donor units. gNDI coupling with FBT (gNDI‐FBT) exhibits a charge‐storage capacity exceeding 190 Fg−1, which is the highest value reported to date for NDI‐based polymer electrodes in aqueous media. For ECDs, gNDI‐FBT remains 100% of initial electrochromism contrast (∆%T = 20%) up to 1200 s. In addition, gNDI‐FBT outperforms its two analogs in OECTs, including lower threshold voltage (0.19 V), faster response time (45.5 ms), and higher volumetric capacitance (197 F cm−3). Moreover, gNDI‐FBT with fluorine atoms leads to the bipolarons delocalization along the polymer backbone and favorable molecular packing for ion–electron transport. Through such weak donor functionalization strategy, this work provides ways for n‐type copolymers tuning to access desirable performance metrics in optical, electrochemical, and bioelectronic applications. [ABSTRACT FROM AUTHOR]

As new and better materials are implemented for organic electrochemical transistors (OECTs), it becomes increasingly important to adopt more economic and environmentally friendly synthesis pathways with respect to conventional transition‐metal‐catalyzed polymerizations. Herein, a series of novel n‐type donor–acceptor‐conjugated polymers based on glycolated lactone and bis‐isatin units are reported. All the polymers are synthesized via green and metal‐free aldol polymerization. The strong electron‐deficient lactone‐building blocks provide low‐lying lowest unoccupied molecular orbital (LUMO) and the rigid backbone needed for efficient electron mobility up to 0.07 cm2 V−1 s−1. Instead, polar atoms in the backbone and ethylene glycol side chains contribute to the ionic conductivity. The resulting OECTs exhibit a normalized maximum transconductance gm,norm of 0.8 S cm−1 and a μC* of 6.7 F cm−1 V−1 s−1. Data on the microstructure show that such device performance originates from a unique porous morphology together with a highly disordered amorphous microstructure, leading to efficient ion‐to‐electron coupling. Overall, the design strategy provides an inexpensive and metal‐free polymerization route for high‐performing n‐type OECTs. [ABSTRACT FROM AUTHOR]

Docetaxel (DTX) is one of the most promising chemotherapeutic agents for a variety of solid tumors. However, the clinical efficacy of the marketed formulation, Taxotere®, is limited due to its poor aqueous solubility, side effects caused by the emulsifier, and low selective DTX distribution in vivo. Here a facile, well-defined, and easy-to-scale up DTX-loaded N-(tert-butoxycarbonyl)-L-phenylalanine end-capped methoxy-poly(ethylene glycol)-block-poly(D,L-lactide) (mPEG-b-PLA-Phe(Boc)) micelles (DTX-PMs) were prepared in an effort to develop a less toxic and more efficacious docetaxel formulation. The physicochemical properties, pharmacokinetics, biodistribution, and in vivo anti-tumor efficacy were evaluated in comparison to the marketed DTX formulation Taxotere®. DTX was successfully encapsulated in the hydrophobic micellar core with a high encapsulation efficiency (> 95%) and a high drug loading capacity (4.81 ± 0.08%). DTX-PMs exhibited outstanding stability in the aqueous environment due to the strong interactions between the terminal amino acid residues and docetaxel. The pharmacokinetic study in Sprague–Dawley rats revealed higher DTX concentrations in both whole blood and plasma for the group treated with DTX-PMs than that treated with Taxotere® due to the improved stability of the micellar formulation. In human non-small cell lung cancer (A549) tumor-bearing Balb/c nude mice, DTX-PMs significantly improved DTX accumulation and stalled DTX elimination in tumors than in bone marrow. Furthermore, only by half of the DTX dosage, our DTX/mPEG-b-PLA-Phe(Boc) micelles can achieve similar therapeutic effects as Taxotere®. Altogether, DTX-PMs hold great promise as a simple and effective drug delivery system for cancer chemotherapy. [ABSTRACT FROM AUTHOR]

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