The artificial brain is conceived as advanced intelligence technology, capable to emulate in‐memory processes occurring in the human brain by integrating synaptic devices. Within this context, ...improving the functionality of synaptic transistors to increase information processing density in neuromorphic chips is a major challenge in this field. In this article, Li‐ion migration promoting long afterglow organic light‐emitting transistors, which display exceptional postsynaptic brightness of 7000 cd m−2 under low operational voltages of 10 V is presented. The postsynaptic current of 0.1 mA operating as a built‐in threshold switch is implemented as a firing point in these devices. The setting‐condition‐triggered long afterglow is employed to drive the photoisomerization process of photochromic molecules that mimic neurotransmitter transfer in the human brain for realizing a key memory rule, that is, the transition from long‐term memory to permanent memory. The combination of setting‐condition‐triggered long afterglow with photodiode amplifiers is also processed to emulate the human responding action after the setting‐training process. Overall, the successful integration in neuromorphic computing comprising stimulus judgment, photon emission, transition, and encoding, to emulate the complicated decision tree of the human brain is demonstrated.
Low power consumption long afterglow organic light‐emitting transistors are fabricated to simultaneously accomplish the functions of in‐memory calculation, light‐emission, and decision‐making process. When combined with optically switchable transistors and photodiode amplifiers, the biological neurotransmitter transfer and biological firing action after spiking excess threshold are mimicked in the chip.
The interest in two‐dimensional conjugated polymers (2D CPs) has increased significantly in recent years. In particular, vinylene‐linked 2D CPs with fully in‐plane sp2‐carbon‐conjugated structures, ...high thermal and chemical stability, have become the focus of attention. Although the Horner‐Wadsworth‐Emmons (HWE) reaction has been recently demonstrated in synthesizing vinylene‐linked 2D CPs, it remains largely unexplored due to the challenge in synthesis. In this work, we reveal the control of crystallinity of 2D CPs during the solvothermal synthesis of 2D‐poly(phenylene‐quinoxaline‐vinylene)s (2D‐PPQVs) and 2D‐poly(phenylene‐vinylene)s through the HWE polycondensation. The employment of fluorinated phosphonates and rigid aldehyde building blocks is demonstrated as crucial factors in enhancing the crystallinity of the obtained 2D CPs. Density functional theory (DFT) calculations reveal the critical role of the fluorinated phosphonate in enhancing the reversibility of the (semi)reversible C−C single bond formation.
We reveal the control of crystallinity during the solvothermal synthesis of 2D‐poly(phenylenequinoxalinevinylene)s (2D‐PPQVs) and 2D‐poly(phenylene‐vinylene)s (2D‐PPVs) through the Horner‐Wadsworth‐Emmons (HWE) polycondensation by the employment of fluorinated phosphonates and rigid aldehyde building blocks.
The covalent linking of acetylenes presents an important route for the fabrication of novel carbon-based scaffolds with potential utilities in a large variety of applications. Beyond that, the ...incorporation of metal atoms into the acetylenic scaffold could significantly improve its physical, chemical and electronic properties, but the synthesis of such metalated materials remains a challenge. Herein, we demonstrate a solvent-mediated strategy for tailoring conjugated acetylenic polymers from metal-free to copper-metallated diacetylenic linkages. The metalation extends light absorption and promotes charge transport in acetylenic polymers. As a result, the Cu-metallated acetylenic polymers on a photocathode exhibit a hydrogen-evolution photocurrent density of 7-70 μA cm
−2
at 0.3 V
vs.
the reversible hydrogen electrode, which is superior to that of their metal-free counterpart. This work offers a feasible strategy to modulate the Cu-metalation of acetylenic polymers, which may inspire further studies in this field.
This work reports a solvent-mediated strategy for tailoring conjugated acetylenic polymers from metal-free to Cu-metalated counterparts, which extends light absorption and promotes charge transport for acetylenic polymers.
Vinylene‐linked two‐dimensional conjugated covalent organic frameworks (V‐2D‐COFs), belonging to the class of two‐dimensional conjugated polymers, have attracted increasing attention due to their ...extended π‐conjugation over the 2D backbones associated with high chemical stability. The Knoevenagel polycondensation has been demonstrated as a robust synthetic method to provide cyano (CN)‐substituted V‐2D‐COFs with unique optoelectronic, magnetic, and redox properties. Despite the successful synthesis, it remains elusive for the relevant polymerization mechanism, which leads to relatively low crystallinity and poor reproducibility. In this work, we demonstrate the novel synthesis of CN‐substituted V‐2D‐COFs via the combination of Knoevenagel polycondensation and water‐assisted dynamic Michael‐addition‐elimination, abbreviated as KMAE polymerization. The existence of C=C bond exchange between two diphenylacrylonitriles (M1 and M6) is firstly confirmed via in situ high‐temperature NMR spectroscopy study of model reactions. Notably, the intermediate M4 synthesized via Michael‐addition can proceed the Michael‐elimination quantitatively, leading to an efficient C=C bond exchange, unambiguously confirming the dynamic nature of Michael‐addition‐elimination. Furthermore, the addition of water can significantly promote the reaction rate of Michael‐addition‐elimination for highly efficient C=C bond exchange within 5 mins. As a result, the KMAE polymerization provides a highly efficient strategy for the synthesis of CN‐substituted V‐2D‐COFs with high crystallinity, as demonstrated by four examples of V‐2D‐COF‐TFPB‐PDAN, V‐2D‐COF‐TFPT‐PDAN, V‐2D‐COF‐TFPB‐BDAN, and V‐2D‐COF‐HATN‐BDAN, based on the simulated and experimental powder X‐ray diffraction (PXRD) patterns as well as N2‐adsorption–desorption measurements. Moreover, high‐resolution transmission electron microscopy (HR‐TEM) analysis shows crystalline domain sizes ranging from 20 to 100 nm for the newly synthesized V‐2D‐COFs.
Synthesis of vinylene‐linked 2D COFs via Knoevenagel polycondensation and in situ water‐assisted Michael‐addition‐elimination: The addition of water can accelerate the Michael‐addition‐elimination for C=C bond exchange.
Two-dimensional sp2-carbon-conjugated covalent organic frameworks (2D sp2c-COFs) featured with fully in-plane π-conjugated skeletons and tunable optoelectronic properties are appealing in ...photo-to-chemical energy conversion. Nevertheless, high-performance photocatalytic performance often suffers from easy carrier recombination and large band gaps. Herein, we reported the synthesis of a benzobisoxazole-linked donor-acceptor (D-A) 2D sp2c-COF (COF-TNOB-P2) via end-capping strategy to facilitate the carrier separation and migration as well as broaden the energy-harvesting capability. Due to the edge-engineered D-A structures, the COF-TNOB-P2 as the photoelectrode presents an excellent photocurrent density up to ∼88 μA/cm2 at 0 V vs. reversible hydrogen electrode, much higher than that of pristine COF-TNOB (56 μA/cm2). Moreover, the photocatalytic hydrogen evolution performance is enhanced from 1028 to 1824 μmol/h/g. Our work highlights the construction of D-A 2D sp2c-COF via lattice edge functionalization methodology for high-performance photocatalysts.
An end-capping strategy is proposed to synthesize benzobisoxazole-linked donor-acceptor (D-A) sp2-carbon-conjugated covalent organic frameworks via exploiting the electron-rich thiophene to functionally modify edges of electron-deficient backbones. The edge-engineered D-A structures facilitate the carrier separation and migration as well as broaden the energy-harvesting capability to further improve photocatalytic performance. Display omitted
•Functional modification lattice edges of benzobisoxazole-linked sp2c-COF to construct donor-acceptor (D-A) structures.•The D-A structures facilitate carrier separation and migration as well as broaden the energy-harvesting capability.•The photocurrent and photocatalytic performances were highly improved via end-capping.
Photoelectrochemical (PEC) water reduction, converting solar energy into environmentally friendly hydrogen fuel, requires delicate design and synthesis of semiconductors with appropriate bandgaps, ...suitable energy levels of the frontier orbitals, and high intrinsic charge mobility. In this work, the synthesis of a novel bithiophene‐bridged donor–acceptor‐based 2D sp2‐carbon‐linked conjugated polymer (2D CCP) is demonstrated. The Knoevenagel polymerization between the electron‐accepting building block 2,3,8,9,14,15‐hexa(4‐formylphenyl) diquinoxalino2,3‐a:2′,3′‐cphenazine (HATN‐6CHO) and the first electron‐donating linker 2,2′‐(2,2′‐bithiophene‐5,5′‐diyl)diacetonitrile (ThDAN) provides the 2D CCP‐HATNThDAN (2D CCP‐Th). Compared with the corresponding biphenyl‐bridged 2D CCP‐HATN‐BDAN (2D CCP‐BD), the bithiophene‐based 2D CCP‐Th exhibits a wide light‐harvesting range (up to 674 nm), a optical energy gap (2.04 eV), and highest energy occupied molecular orbital–lowest unoccupied molecular orbital distributions for facilitated charge transfer, which make 2D CCP‐Th a promising candidate for PEC water reduction. As a result, 2D CCP‐Th presents a superb H2‐evolution photocurrent density up to ≈7.9 µA cm−2 at 0 V versus reversible hydrogen electrode, which is superior to the reported 2D covalent organic frameworks and most carbon nitride materials (0.09–6.0 µA cm−2). Density functional theory calculations identify the thiophene units and cyano substituents at the vinylene linkage as active sites for the evolution of H2.
A bithiophene‐bridged D–A‐based 2D sp2‐carbon‐linked conjugated polymer (2D CCP‐Th) is synthesized via Knoevenagel polymerization. Benefiting from the robust sp2‐carbon‐linked conjugations and donor–acceptor structures, when employed as a photocathode for water reduction, 2D CCP‐Th demonstrates a superb saturated photocurrent density (5.5 µA cm−2 at 0.3 V and 7.9 µA cm−2 at 0 V vs reversible hydrogen electrode).
Photoelectrochemical (PEC) water reduction, converting solar energy into environmentally friendly hydrogen fuel, requires delicate design and synthesis of semiconductors with appropriate bandgaps, ...suitable energy levels of the frontier orbitals, and high intrinsic charge mobility. In this work, the synthesis of a novel bithiophene-bridged donor-acceptor-based 2D sp
-carbon-linked conjugated polymer (2D CCP) is demonstrated. The Knoevenagel polymerization between the electron-accepting building block 2,3,8,9,14,15-hexa(4-formylphenyl) diquinoxalino2,3-a:2',3'-cphenazine (HATN-6CHO) and the first electron-donating linker 2,2'-(2,2'-bithiophene-5,5'-diyl)diacetonitrile (ThDAN) provides the 2D CCP-HATNThDAN (2D CCP-Th). Compared with the corresponding biphenyl-bridged 2D CCP-HATN-BDAN (2D CCP-BD), the bithiophene-based 2D CCP-Th exhibits a wide light-harvesting range (up to 674 nm), a optical energy gap (2.04 eV), and highest energy occupied molecular orbital-lowest unoccupied molecular orbital distributions for facilitated charge transfer, which make 2D CCP-Th a promising candidate for PEC water reduction. As a result, 2D CCP-Th presents a superb H
-evolution photocurrent density up to ≈7.9 µA cm
at 0 V versus reversible hydrogen electrode, which is superior to the reported 2D covalent organic frameworks and most carbon nitride materials (0.09-6.0 µA cm
). Density functional theory calculations identify the thiophene units and cyano substituents at the vinylene linkage as active sites for the evolution of H
.
Abstract
A two‐dimensional (2D) sp
2
‐carbon‐linked conjugated polymer framework (2D CCP‐HATN) has a nitrogen‐doped skeleton, a periodical dual‐pore structure and high chemical stability. The polymer ...backbone consists of hexaazatrinaphthalene (HATN) and cyanovinylene units linked entirely by carbon–carbon double bonds. Profiting from the shape‐persistent framework of 2D CCP‐HATN integrated with the electrochemical redox‐active HATN and the robust sp
2
carbon‐carbon linkage, 2D CCP‐HATN hybridized with carbon nanotubes shows a high capacity of 116 mA h g
−1
, with high utilization of its redox‐active sites and superb cycling stability (91 % after 1000 cycles) and rate capability (82 %, 1.0 A g
−1
vs. 0.1 A g
−1
) as an organic cathode material for lithium‐ion batteries.
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