Synthesis of a monolayer fullerene network.

Two-dimensional (2D) carbon materials, such as graphene, have attracted particular attention owing to the exceptional carrier transport characteristics that arise from the unique π-electron system in their conjugated carbon network structure1-4. To complement zero-bandgap graphene, material scientists have devoted considerable effort to identifying 2D carbon materials5-8. However, it is a challenge to prepare large-sized single-crystal 2D carbon materials with moderate bandgaps5,9. Here we prepare a single-crystal 2D carbon material, namely monolayer quasi-hexagonal-phase fullerene (C60), with a large size via an interlayer bonding cleavage strategy. In this monolayer polymeric C60, cluster cages of C60 are covalently bonded with each other in a plane, forming a regular topology that is distinct from that in conventional 2D materials. Monolayer polymeric C60 exhibits high crystallinity and good thermodynamic stability, and the electronic band structure measurement reveals a transport bandgap of about 1.6 electronvolts. Furthermore, an asymmetric lattice structure endows monolayer polymeric C60 with notable in-plane anisotropic properties, including anisotropic phonon modes and conductivity. This 2D carbon material with a moderate bandgap and unique topological structure offers an interesting platform for potential application in 2D electronic devices.

Iminyl-Radical-Mediated Formation of Covalent Au-N Bonds for Molecular Junctions.

The interaction between organic radicals and transition metals plays a crucial role in radical-mediated chemical reactions, functional devices, and biocatalysis. Characterizing such interactions, however, remains a long-standing challenge due to the inherently high reactivity of radical species. Here, using a scanning tunneling microscope breaking junction (STM-BJ) technique, we are able to detect the interaction mode between iminyl radicals and the gold surface at a single molecule level. We show that the free iminyl radicals generated through photochemical N-O bond homolysis of oxime esters react toward the gold electrode surface and produce covalent Au-N bonds. Intriguingly, we find that the Au-N bonding reactions lead to the formation of robust and highly conductive single-molecule junctions. These findings provide not only insights into the mechanism of iminyl-radical-involved reactions but also a facile photolysis method to create a new type of covalent electrode-molecule bonding contact for molecular devices.

Boosting the Thermoelectric Performance of the Doped DPP-EDOT Conjugated Polymer by Incorporating an Ionic Additive.

The thermoelectric (TE) performance of organic materials is limited by the coupling of Seebeck coefficient and electrical conductivity. Herein a new strategy is reported to boost the Seebeck coefficient of conjugated polymer without significantly reducing the electrical conductivity by incorporation of an ionic additive DPPNMe3 Br. The doped polymer PDPP-EDOT thin film exhibits high electrical conductivity up to 1377 ± 109 S cm-1 but low Seebeck coefficient below 30 µV K-1 and a maximum power factor of 59 ± 10 µW m-1 K-2 . Interestingly, incorporation of small amount (at a molar ratio of 1:30) of DPPNMe3 Br into PDPP-EDOT results in the significant enhancement of Seebeck coefficient along with the slight decrease of electrical conductivity after doping. Consequently, the power factor (PF) is boosted to 571 ± 38 µW m-1 K-2 and ZT reaches 0.28 ± 0.02 at 130 °C, which is among the highest for the reported organic TE materials. Based on the theoretical calculation, it is assumed that the enhancement of TE performance for the doped PDPP-EDOT by DPPNMe3 Br is mainly attributed to the increase of energetic disorder for PDPP-EDOT.

The Increasing Number of Electron Reservoirs in Nonporous, High-Conducting Coordination Polymers Cux BHT (x = 3, 4, and 5, BHT = Benzenehexathiol) for Improved Faradaic Capacitance.

Although asymmetric supercapacitors (ASCs) can achieve high energy density, the lifespan and power density are severely suppressed due to the low conductivity of using pseudocapacitive or battery-type electrode materials. Recently, nonporous conductive coordination polymers (c-CPs) have sparked interests in supercapacitors. However, their performance is expected to be limited by the nonporous features, low specific surface area and absence of ion-diffusion channels. Here, it is demonstrated that the capacity of nonporous CPs will be significantly enhanced by maximizing the number of faradaic redox sites in their structures through a comparative investigation on three highly conductive nonporous c-CPs, Cux BHT(x = 3, 4, 5.5). They show excellent capacitance of 312.1 F g-1 (374.5 C g-1 ) (Cu3 BHT), 186.7 F g-1 (224.0 C g-1 ) (Cu4 BHT) and 89.2 F g-1 (107.0 C g-1 ) (Cu5.5 BHT) at 0.5 A g-1 in a sequence related to the number of electron storage units in structures and outstanding rate performance and cycle stability. Furthermore, the constructed Cu3 BHT//MnO2 ASC device exhibits capacity retention of 92% (after 1500 cycles at 3 A g-1 ) and delivers a high energy density of 39.1 Wh kg-1 at power density of 549.6 W kg-1 within a large working potential window of 0-2.2 V.

1D Mixed-Stack Cocrystals Based on Perylene Diimide toward Ambipolar Charge Transport.

There is very limited repertoire of organic ambipolar semiconductors to date. Electron donor-acceptor alternative stacking is a unique and important binary motif for 1D mixed-stack cocrystals, opening up possibilities for the development of organic ambipolar semiconductors. Herein, four 1D mixed-stack cocrystals using N,N'-bis(perfluorobutyl)-1,7-dicyanoperylene-3,4:9,10-bis(dicarboximide) (PDICNF) as the acceptor and anthracene, pyrene, perylene, and meso-diphenyl tetrathia[22]annulene[2,1,2,1] (DPTTA) as the donors are achieved in a stoichiometric ratio (D:A = 1:1) through solution or vapor processed methods. Their packing structures, energy levels, charge transfer interactions, coassembling behaviors, and molecular orientations are systematically investigated by single-crystal X-ray analysis, absorption spectra, fluorescence quenching, Job's curve plot, and polarized photoluminescence measurements with the help of theoretical calculations. The donor-acceptor alternative stacking direction coincides with the long axis for all the four cocrystals. The field-effect transistors based on Pyrene-PDICNF show the electron mobility up to 0.19 cm2 V-1 s-1 , which is the highest value among perylene diimide-based cocrystals. Moreover, DPTTA-PDICNF cocrystals possess well-balanced electron and hole mobility with 1.7 × 10-2 and 2.0 × 10-2  cm2 V-1 s-1 respectively due to both hole and electron strong superexchange interactions, shedding light on the design of 1D mixed-stack cocrystals with excellent ambipolar transport behaviors.

Chemical doping of organic semiconductors for thermoelectric applications.

Doping is essential to manipulate the electrical performance of both thermoelectric (TE) materials and organic semiconductors (OSCs). Although organic thermoelectric (OTE) materials have experienced a rapid development over the past decade, the chemical doping of OSCs for TE applications lags behind, which has limited further breakthroughs in this cutting-edge field. Recently, increasing efforts have been devoted to the development of energetically matched host and dopant molecules, exploring novel doping methods and revealing the doping mechanisms. This tutorial review covers the basic mechanisms, fundamental requirements, recent advances and remaining challenges of chemical doping in OSCs for TE applications. We first present the basic knowledge of the trade-off relationship in TE materials and its critical requirements for doped OSCs, followed by a brief introduction of recent advances in the molecular design of OSCs and dopants. Moreover, we provide an overview of the existing categories of doping mechanisms and methods, and more importantly, emphasize the summarized doping strategies for the state-of-the-art OTE materials. Finally, challenges and perspectives on the chemical doping of OSCs are proposed to highlight the research directions that deserve attention towards a bright future of OTE materials.

Enabling Multifunctional Organic Transistors with Fine-Tuned Charge Transport.

Organic field-effect transistors (OFETs) are promising candidates for many electronic applications not only because of the intrinsic features of organic semiconductors in mechanical flexibility and solution processability but also owing to their multifunctionalities promised by combined signal switching and transduction properties. In contrast to rapid developments of high performance devices, the construction of multifunctional OFETs remains challenging. A key issue is fine-tuning the charge transport by modulating electric fields that are coupled with various external stimuli. Given that the charge transport is determined by complicated factors involving material and device engineering, the development of effective strategies to manipulate charge transport is highly desired toward state-of-the-art multifunctional OFETs. In this Account, we present our recent progress on device-engineered OFETs for sensing applications and thermoelectric studies of organic semiconductors. The interactions between organic semiconductors and the target analyte determine the performance of chemical sensors based on OFETs. We introduced gas receptors and in situ tailored molecular antenna on the surface of ultrathin active layers. The engineered interfaces enable direct and specific semiconductor-analyte interactions, as demonstrated in developed chemical sensors and biosensors with prominent sensitivity and good selectivity. In comparison with chemical stimuli, many physical stimuli such as pressure typically possess a limit effect on the charge transport properties of organic semiconductors. By utilizing the suspended-gate geometry, the carrier concentration in a conductive channel can be controlled quantitatively by the pressure dominated changes in the capacitance of an air dielectric layer, allowing for ultrasensitive pressure detection in a unique manner. More importantly, the transduced current can be further processed by a synaptic OFET, in which the proton/electron coupling interfaces contribute to the dynamic modulation of carrier concentration, thus mimicking biological synapses. The integrated pressure sensor and synaptic OFETs, namely, the dual-organic-transistor-based tactile-perception element, has exhibited promising applications in artificial intelligence elements. Aiming at revealing thermoelectric (TE) properties of organic semiconductors, we also investigated field-modulated TE performance of several high-mobility semiconductors by varying the driving electric field to the temperature gradient. This has been confirmed to offer a strategy to accelerate the search for promising TE materials from well-developed organic semiconductors. By tuning the charge transport process in the device, the functional modulation of OFETs has experienced significant progress in the preceding years. The exploration of new ways to create OFETs with more fascinating functionalities is still full of opportunities to obtain greater benefit from organic transistors.

Highly Conductive Cobalt Perthiolated Coronene Complex for Efficient Hydrogen Evolution.

Metal-bis(dithiolene) is one of the most promising structures showing redox activity, excellent electron transport and magnetic properties as well as catalytic activities. Perthiolated coronene (PTC), an emerging highly symmetric ligand containing the smallest graphene nanoplate was employed to manufacture a hybrid material with fused metal-bis(dithiolene) and graphene nanoplate, and it has been demonstrated as an efficient strategy for the construction of multifunctional materials recently. Herein, Co-PTC, a 2D MOF containing Co-bis(dithiolene) and coronene units is prepared via a homogeneous reaction for the first time as powder samples, which are bar-shaped microparticles composed of nanosheets. A neutral formula of [Co3 (C24 S12 )]n is verified for Co-PTC. Co-PTC plays an ultrahigh conductivity of approximately 45 S cm-1 at room temperature as compressed samples, which is among the highest value ever reported for the compressed powder samples of conducting MOFs. Moreover, Co-PTC exhibits good electrocatalytic performance in the hydrogen evolution reaction (HER) with a Tafel slope of 189 mV decade-1 and an operating overpotential of 227 mV at 10 mA cm-1 with pH=0, as well as a remarkable stability in the extremely acidic aqueous solutions, which is the best hydrogen evolution properties among metal-organic compounds.

Backbone Structure Effect on the Thermoelectric Properties of IDT-Based p-Type Conjugated Polymers.

Four conjugated polymers are synthesized through indacenodithiohene (IDT) unit copolymerized with thiophene and thiophene derivatives. Indacenodithiohene-co-thieno[3,2-b]thiophene (IDT-TT) and indacenodithiohene-co-trans-1,2-di(2-thienyl)ethylene (IDT-TVT) exhibit better charge transport mobilities than indacenodithiohene-co-thiophene (IDT-T) and indacenodithiohene-co-3,4-ethoxylene dioxythiophene (IDT-EDOT), and also display superior thermoelectric properties after doping. Theoretical calculations suggest that IDT-EDOT and IDT-TVT have better coplanarities; the inferior performance for IDT-EDOT might be due to its low molecular weight. Meanwhile, it is worth mentioning that via the synergistic effect of two dopants (CN6CP, CuTFSI), the electrical conductivities of the polymers are further improved. The XPS data shows that the coordination interaction between copper ion and the cyano groups of CN6CP introduces cupric ions into the polymer films, which leads to the increase of the doping ratio.

Paramagnetic Conducting Metal-Organic Frameworks with Three-Dimensional Structure.

3D well-crystallized metal-organic frameworks (MOFs), M-THBQ (M=Fe, Co, Mn, THBQ=tetrahydroxybenzoquinone), are synthesized and characterized. Their structures are determined as cubic cell in the group of Pm 3 ‾ from powder X-ray diffraction data, and their properties of electronic, magnetic and spectroscopic are also investigated. They are all semiconductors, and Fe-THBQ exhibits the air-stable n-type thermoelectric characteristic as its Seebeck coefficient reaches -130 µV K-1 , and the electrical conductivity is 2.7×10-4  S cm-1 at 300 K. Additional, M-THBQ are paramagnetic, and the value of Weiss constant of Fe-THBQ is -219.37 K, indicating the existence of robust intramolecular antiferromagnetic exchanges. Meanwhile, they display strong absorption bands in the range of 220 to 1000 nm, suggest M-THBQ could have the potential to become photoabsorbers, and Fe-THBQ exhibits a narrow band gap of 0.63 eV according to the ultraviolet absorption edge spectrum.

Highly Conducting Organic-Inorganic Hybrid Copper Sulfides Cux C6 S6 (x=4 or 5.5): Ligand-Based Oxidation-Induced Chemical and Electronic Structure Modulation.

Conductive coordination polymers (CPs) have potential in a wide range of applications because of their inherent structural and functional diversity. Three electrically conductive CPs (Cux C6 S6 , x=3, 4 or 5.5) derived from the same organic linker (benzenehexathiol) and metal node (copper(I)) were synthesized and studied. Cux C6 S6 materials are organic-inorganic hybrid copper sulfides comprising a π-π stacking structure and cooper sulfur networks. Charge-transport pathways within the network facilitate conductivity and offer control of the Fermi level through modulation of the oxidation level of the non-innocent redox-active ligand. Two Cux C6 S6 (x=4 or 5.5) CPs display high electrical conductivity and they feature a tunable structural topology and electronic structure. Cu4 C6 S6 and Cu5.5 C6 S6 act as degenerate semiconductors. Moreover, Cu5.5 C6 S6 is a p-type thermoelectric material with a ZT value of 0.12 at 390 K, which is a record-breaking performance for p-type CPs.

High-Performance Polymer Solar Cells Achieved by Introducing Side-Chain Heteroatom on Small-Molecule Electron Acceptor.

Side chains of photovoltaic materials play an important role in determining charge transport property, film morphology, and the corresponding device performance. In this work, two new acceptor materials, ATT-6 and ATT-7 with different side chains, m-hexylphenyl and m-hexyloxyphenyl on the indacenodithiophene, are designed and synthesized for applications in non-fullerene polymer solar cells. ATT-7 shows a higher absorption coefficient, increased crystallinity, and improved electron mobility in comparison with ATT-6. Using wide-bandgap polymer poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5',7'-bis(2-ethylhexyl)benzo[1',2'-c:4',5'-c']dithiophene-4,8-dione)] (PBDB-T) as donor, optimized devices based on PBDB-T:ATT-7 and PBDB-T:ATT-6 delivers power conversion efficiencies of 10.30% and 8.39%, respectively. The higher performance of ATT-7-based device can be attributed to efficient exciton dissociation, reduced bimolecular recombination, and enhanced and balanced charge carrier mobilities. These results indicate that side-chain modification is an easy but efficient way in the design of high-performance non-fullerene acceptors.

Selenium-Substituted Diketopyrrolopyrrole Polymer for High-Performance p-Type Organic Thermoelectric Materials.

Development of high-performance organic thermoelectric (TE) materials is of vital importance for flexible power generation and solid-cooling applications. Demonstrated here is the significant enhancement in TE performance of selenium-substituted diketopyrrolopyrrole (DPP) derivatives. Along with strong intermolecular interactions and high Hall mobilities of 1.0-2.3 cm2 V-1 s-1 in doping-states for polymers, PDPPSe-12 exhibits a maximum power factor and ZT of up to 364 µW m-1 K-2 and 0.25, respectively. The performance is more than twice that of the sulfur-based DPP derivative and represents the highest value for p-type organic thermoelectric materials based on high-mobility polymers. These results reveal that selenium substitution can serve as a powerful strategy towards rationally designed thermoelectric polymers with state-of-the-art performances.

Quantum Spin Liquid from a Three-Dimensional Copper-Oxalate Framework.

The quantum spin liquid (QSL) state is of great interest in relation to quantum computation and superconductivity and the search for new QSL materials is a current challenge in chemistry. Existing inorganic and molecular QSL compounds have two-dimensional structures, with spins arranged on triangular and kagome lattices, whereas three-dimensional structures with QSL characteristics are rare. In the copper-oxalate framework compound [(C2H5)3NH]2Cu2(C2O4)3, Cu(II) is coordinated with three bisbidentate oxalate bridges to form a three-dimensional (10,3) lattice and this produces a strong antiferromagnetic interaction between Cu2+ (S = 1/2) atoms (θ = -180 K). No long-range ordering (LRO) was observed in either magnetic susceptibility or specific heat measurements down to 2 K. Absence of LRO was further confirmed by µSR measurements down to 60 mK, indicating that it is a gapless QSL with f > 3000. Due to Jahn-Teller distortion and partial dimerization, the effective dimensionality of the magnetic lattice is reduced. This compound nevertheless highlights the great potential for obtaining QSLs of varying dimensionality from metal-organic frameworks.

Highly Conducting Neutral Coordination Polymer with Infinite Two-Dimensional Silver-Sulfur Networks.

Highly crystalline films of a silver-based coordination polymer, [Ag5(C6S6)] n (Ag-BHT, BHT = benzenehexathiol), have been prepared. The structure of Ag-BHT, solved by combining rotation electron diffraction and powder X-ray diffraction techniques, indicates that it has a lamellar structure with alternatively stacked two-dimensional Ag-S networks and layers composed of one-dimensional metal-dithiolene polymers. In addition, the polycrystalline Ag-BHT film shows high electrical conductivity of up to 250 S·cm-1 at 300 K. The ultraviolet-photoelectron spectroscopy and electronic band structure calculations reveal that this can be attributed to the partially filled valence band and the unique two-dimensional Ag-S networks.

Organic Donor-Acceptor Complexes as Novel Organic Semiconductors.

Organic donor-acceptor (DA) complexes have attracted wide attention in recent decades, resulting in the rapid development of organic binary system electronics. The design and synthesis of organic DA complexes with a variety of component structures have mainly focused on metallicity (or even superconductivity), emission, or ferroelectricity studies. Further efforts have been made in high-performance electronic investigations. The chemical versatility of organic semiconductors provides DA complexes with a great number of possibilities for semiconducting applications. Organic DA complexes extend the semiconductor family and promote charge separation and transport in organic field-effect transistors (OFETs) and organic photovoltaics (OPVs). In OFETs, the organic complex serves as an active layer across extraordinary charge pathways, ensuring the efficient transport of induced charges. Although an increasing number of organic semiconductors have been reported to exhibit good p- or n-type properties (mobilities higher than 1 or even 10 cm2 V-1 s-1), critical scientific challenges remain in utilizing the advantages of existing semiconductor materials for more and wider applications while maintaining less complicated synthetic or device fabrication processes. DA complex materials have revealed new insight: their unique molecular packing and structure-property relationships. The combination of donors and acceptors could offer practical advantages compared with their unimolecular materials. First, growing crystals of DA complexes with densely packed structures will reduce impurities and traps from the self-assembly process. Second, complexes based on the original structural components could form superior mixture stacking, which can facilitate charge transport depending on the driving force in the coassembly process. Third, the effective use of organic semiconductors can lead to tunable band structures, allowing the operation mode (p- or n-type) of the transistor to be systematically controlled by changing the components. Finally, theoretical calculations based on cocrystals with unique stacking could widen our understanding of structure-property relationships and in turn help us design high-performance semiconductors based on DA complexes. In this Account, we focus on discussing organic DA complexes as a new class of semiconducting materials, including their design, growth methods, packing modes, charge-transport properties, and structure-property relationships. We have also fabricated and investigated devices based on these binary crystals. This interdisciplinary work combines techniques from the fields of self-assembly, crystallography, condensed-matter physics, and theoretical chemistry. Researchers have designed new complex systems, including donor and acceptor compounds that self-assemble in feasible ways into highly ordered cocrystals. We demonstrate that using this crystallization method can easily realize ambipolar or unipolar transport. To further improve device performance, we propose several design strategies, such as using new kinds of donors and acceptors, modulating the energy alignment of the donor (ionization potential, IP) and acceptor (electron affinity, EA) components, and extending the π-conjugated backbones. In addition, we have found that when we use molecular "doping" (2:1 cocrystallization), the charge-transport nature of organic semiconductors can be switched from hole-transport-dominated to electron-transport-dominated. We expect that the formation of cocrystals through the complexation of organic donor and acceptor species will serve as a new strategy to develop semiconductors for organic electronics with superior performances over their corresponding individual components.

Arraying Octahedral {Cr2Dy4} Units into 3D Single-Molecule-Magnet-Like Inorganic Compounds with Sulfate Bridges.

Two novel 3D pure inorganic compounds based on [Cr2Dy4(µ4-O)2(µ3-OH)4]10+ cluster units and sulfate anions are presented. Both complexes exhibit single-molecule-magnet (SMM)-like behavior. Permutation of the magnetic moment direction among SMM-like cluster units has a significant effect on the performance of molecular nanomagnets, and directional consistency shows obvious advantages.

Single-Molecule Magnet Behavior of 1D Coordination Polymers Based on DyZn2(salen)2 Units and Pyridin- N-Oxide-4-Carboxylate: Structural Divergence and Magnetic Regulation.

Two 1D coordination polymers composed of DyZn2(salen)2 units and pyridin- N-oxide-4-carboxylate have been prepared by solvothermal reactions. Complex 1 with the formula {[DyZn2(La)2(POC)](OH)(ClO4)}·H2O·MeOH [H2La] = N, N'-bis(3-methoxysalicylidene)-1,3-diaminopropane, POC- = pyridin- N-oxide-4-carboxylate] is composed of a zigzag chain cation [DyZn2(La)2(POC)] n2 n+ as well as isolated hydroxide and perchlorate anions. Complex 2 with the formula {[Dy3Zn7(Lb)6(POC)6](OH)3(ClO4)2}·9H2O [H2Lb] = N, N'-bis(3-methoxysalicylidene)-1,2-diaminoethane] is also an ionic compound containing isolated hydroxide and perchlorate anions, but its cation shows a novel nanowire structure, in which six-coordinate zinc(II) ions with C3 symmetry act as the axis and [DyZn2(Lb)2(POC)]2+ structural units as spiral leaves. Complex 1 shows good single-molecule magnet performance with an Ueff/ k value of 235.3(3.1) K ( Hdc = 0 Oe), one of the largest values for coordination polymers. A butterfly-shaped magnetic hysteresis loop can be monitored at as high as 3.8 K for 1, while a dc field is necessary for complex 2 to display slow magnet relaxation owing to the quantum-tunneling effect, with a much smaller Ueff/ k value of 14.6(0.2) K ( Hdc = 1000 Oe). The difference of magnetic properties has been explained using detailed ab initio calculations.

Highly Conducting Polythiophene Thin Films with Less Ordered Microstructure Displaying Excellent Thermoelectric Performance.

Polythiophene (PTh) with highly regular molecular structure is synthesized as nearly amorphous thin films by electrochemical methods in a BFEE/DTBP mixed medium (BFEE = boron fluoride ethyl ether; DTBP = 2,6-di-tert-butypyridine). The doping level and film morphology of PTh are modulated through adjusting the current density applied during the polymerization process. A combined analysis with solid-state NMR, FT-IR, and Raman spectra reveals the molecular structural regularity of the resulted PTh films, which leads to the highest electrical conductivity up to 700 S cm-1 for films obtained under an optimized current density of 1 mA cm-2 . By applying the self-heating 3ω-method, thermal conductivities are measured along the in-plane direction. A highly reduced Lorenz number of 6.49 × 10-9 W Ω K-2 and low lattice thermal conductivity of 0.21 W m-1 K-1 were extracted based on the analyses of the electrical and thermal conductivities according to the Wiedemann-Franz Law; the former is about one-third of the Sommerfeld value. Finally, the maximized ZT value can reach up to 0.10 under room temperature, which shows that the highly conducting polymers with less ordered structure is the practical direction for developing organic thermoelectric materials.

Superconductivity in a Copper(II)-Based Coordination Polymer with Perfect Kagome Structure.

A highly crystalline copper(II) benzenehexathiolate coordination polymer (Cu-BHT) has been prepared. The two-dimensional kagome structure has been confirmed by powder X-ray diffraction, high-resolution transmission electron microscopy, and high-resolution scanning transmission electron microscopy. The as-prepared sample exhibits bulk superconductivity at about 0.25 K, which is confirmed by the zero resistivity, AC magnetic susceptibility, and specific heat measurements. Another diamagnetic transition at about 3 K suggests that there is a second superconducting phase that may be associated with a single layer or few layers of Cu-BHT. It is the first time that superconductivity has been observed in a coordination polymer.