Two‐Dimensional Conjugated Polymer Synthesized by Interfacial Suzuki Reaction: Towards Electronic Device Applications

2D Conjugated Polymer Thin Films for Organic Electronics: Opportunities and Challenges

2D conjugated polymers (2DCPs) possess extended in-plane π-conjugated lattice and out-of-plane π-π stacking, which results in enhanced electronic performance and potentially unique band structures. These properties, along with predesignability, well-defined channels, easy postmodification, and order structure attract extensive attention from material science to organic electronics. In this review, the recent advance in the interfacial synthesis and conductivity tuning strategies of 2DCP thin films, as well as their application in organic electronics is summarized. Furthermore, it is shown that, by combining topology structure design and targeted conductivity adjustment, researchers have fabricated 2DCP thin films with predesigned active groups, highly ordered structures, and enhanced conductivity. These films exhibit great potential for various thin-film organic electronics, such as organic transistors, memristors, electrochromism, chemiresistors, and photodetectors. Finally, the future research directions and perspectives of 2DCPs are discussed in terms of the interfacial synthetic design and structure engineering for the fabrication of fully conjugated 2DCP thin films, as well as the functional manipulation of conductivity to advance their applications in future organic electronics.

Recent advances in two-dimensional polymers: synthesis, assembly and energy-related applications

Two-dimensional polymers (2DPs) are a class of 2D crystalline polymer materials with definite structures, which have outstanding physical-chemical and electronic properties. They cleverly link organic building units through strong covalent bonds and can construct functional 2DPs through reasonable design and selection of different monomer units to meet various application requirements. As promising energy materials, 2DPs have developed rapidly in recent years. This review first introduces the basic overview of 2DPs, such as their historical development, inherent 2D characteristics and diversified topological advantages, followed by the summary of the typical 2DP synthesis methods recently (including "top-down" and "bottom-up" methods). The latest research progress in assembly and processing of 2DPs and the energy-related applications in energy storage and conversion are also discussed. Finally, we summarize and prospect the current research status, existing challenges, and future research directions of 2DPs.

Two-Dimensional Conjugated Polymers: a New Choice For Organic Thin-Film Transistors

Organic thin-film transistors (OTFTs) as a vital component among transistors have shown great potential in smart sensing, flexible displays, and bionics due to their flexibility, biocompatibility and customizable chemical structures. Even though linear conjugated polymer semiconductors are common for constructing channel materials of OTFTs, advanced materials with high charge carrier mobility, tunable band structure, robust stability, and clear structure-property relationship are indispensable for propelling the evolution of OTFTs. Two-dimensional conjugated polymers (2DCPs), featured with conjugated lattice, tailorable skeletons, and functional porous structures, match aforementioned criteria closely. In this review, we firstly introduce the synthesis of 2DCP thin films, focusing on their characteristics compatible with the channels of OTFTs. Subsequently, the physics and operating mechanisms of OTFTs and the applications of 2DCPs in OTFTs are summarized in detail. Finally, the outlook and perspective in the field of OTFTs using 2DCPs are provided as well.

Application of conjugated materials in muscle movement recovery process

Conjugate materials have a good application effect in muscle movement recovery. This article aims to provide more references for the practical application of conjugated materials in sports recovery. This paper takes the students of the local physical education college as the experimental object, and selects the students who have sports muscle fatigue or injury for the test. In this paper, they are randomly divided into two groups: the experimental group and the control group, with 19 students in each group. The experimental group used the conjugate material in this paper for muscle movement recovery, while the control group used the traditional method for muscle movement recovery. This paper tested the peak torque, total work done, maximum radial displacement, and contraction time of two groups of students after initial exercise and muscle recovery. The experimental results showed that after 80 h of muscle movement recovery, the peak torque values of isometric contraction (264.59) and concentric contraction (160.81) of students in the experimental group were higher than those of students in the control group (233.79) and concentric contraction (130.43), and the difference was statistically significant (p < 0.05); the isometric contraction time (30.02) and concentric contraction time (29.31) of the experimental group were also higher than those of the control group (27.31) and concentric contraction time (24.58), which was statistically significant (p < 0.05). This study shows that conjugated materials have a significant effect on promoting muscle recovery. They not only help to increase the peak torque of muscle isometric contraction and concentric contraction, but also increase the time of muscle contraction and improve muscle mass.

Photoresponse of CVD grown crystalline quantum dot-embedded covalent organic framework thin film

Covalent organic frameworks (COFs) are a new family of novel 2D materials which are highly sought after for integration into future sensors and other devices for their highly porous structures and large surface areas. However, low-temperature large-area growth of these semiconductive materials with a clean surface for direct device applications is still a challenging task. To provide an on-chip photonic device, a COF366-Quantum dot (COF366-QDs) thin-film-based device fabricated by in situ chemical vapor deposition (CVD) is presented. The high-resolution transmission electron microscopy (HRTEM) displays the formation of the periodic, crystalline and porous framework of the COF layer with mono-dispersed QDs of average particle size of ∼2.5-3 nm. The fabricated COF366-QD layer acts as a photoactive layer in the photonic device with an Au-COFQD-Au structure where a conduction path is formed between the metal electrodes through a network of COF layer with embedded QDs. The device shows photoactive response under 514 nm visible light with a very low dark current of 4.36 × 10-11 A with a minimum light detection capability of 160 nW and a responsivity of ∼3.42 A W-1. The photonic device was highly stable for successive switching cycles with very low attenuation. To our knowledge, this is the first report of a Quantum dot embedded COF366 thin-film by chemical vapor deposition. The proposed interfacing of COF366-QD thin-films on silicon substrate using in situ low-temperature CVD technique can be highly valuable for the development of transfer-free, clean, and low-cost preparation of industrial-scale organic electronics, optoelectronic device applications, and lab-on-chip based technologies for a wide range of future applications.

Integrating Unexpected High Charge-Carrier Mobility and Low-Threshold Lasing Action in an Organic Semiconductor

Integrating high charge-carrier mobility and low-threshold lasing action in an organic semiconductor is crucial for the realization of an electrically pumped laser, but remains a great challenge. Herein, we present an organic semiconductor, named as 2,7-di(2-naphthyl)-9H-fluorene (LD-2), which shows an unexpected high charge-carrier mobility of 2.7 cm²  V^-1  s^-1 and low-threshold lasing characteristic of 9.43 μJ cm^-2 and 9.93 μJ cm^-2 and high-quality factor (Q) of 2131 and 1684 at emission peaks of 420 and 443 nm, respectively. Detailed theoretical calculations and photophysical data analysis demonstrate that a large intermolecular transfer integral of 10.36-45.16 meV together with a fast radiative transition rate of 8.0×10⁸  s^-1 are responsible for the achievement of the superior integrated optoelectronic properties in the LD-2 crystal. These optoelectronic performances of LD-2 are among the highest reported low-threshold lasing organic semiconductors with efficient charge transport, suggesting its promise for research of electrically pumped organic lasers (EPOLs).

Defect-Free Alternating Conjugated Polymers Enabled by Room- Temperature Stille Polymerization

The Stille cross-coupling polymerization is one of the most efficient synthetic methods for donor-acceptor (D-A) type π-conjugated polymers (CPs). Nevertheless, thermal-activation Stille polymerization readily produced homocoupling defects, resulting in batch-to-batch variations in copolymers quality and deteriorating the device performance of electronics and optoelectronics. Here, a room-temperature Stille-type polymerization was developed, the utility and generality of which were demonstrated by synthesis of twelve D-A CPs with high molecular weights. Importantly, the resultant copolymers possessed no homocoupling (hc) structural defects, while hc reactions were observed in the thermal-activation Stille reactions. Thus, the organic field-effect transistors (OFETs) based on the former exhibited twofold higher charge transport mobility (2.10 cm²  V^-1  s^-1 ), since it possessed stronger crystallinity and lower trap density of states (tDOS).

Development of metal-free layered semiconductors for 2D organic field-effect transistors

To this day, the active components of integrated circuits consist mostly of (semi-)metals. Concerns for raw material supply and pricing aside, the overreliance on (semi-)metals in electronics limits our abilities (i) to tune the properties and composition of the active components, (ii) to freely process their physical dimensions, and (iii) to expand their deployment to applications that require optical transparency, mechanical flexibility, and permeability. 2D organic semiconductors match these criteria more closely. In this review, we discuss a number of 2D organic materials that can facilitate charge transport across and in-between their π-conjugated layers as well as the challenges that arise from modulation and processing of organic polymer semiconductors in electronic devices such as organic field-effect transistors.

Electrochemical Synthesis of Large Area Two-Dimensional Metal-Organic Framework Films on Copper Anodes

Owing to their excellent physical and electrical properties, metal-organic framework (MOF) materials with well-defined supramolecular structures have received extensive research attention. However, the fabrication of large-area two-dimensional (2D) MOF films is still a significant challenge. Herein, we propose a novel electrochemical (EC) synthesis method for the preparation of large-area Cu₃ (HHTP)₂ MOF film on single-crystal Cu (100) anode. The surface reaction was achieved via charge-induced molecular assembly. The synthesized MOF film exhibited a high crystalline quality with an electrical conductivity of approximately 0.087 S cm^-1 , which was around 1000 times larger than the previously reported values for the same material prepared by the interface method. In addition, Cu₂ (MTCP), Cu₃ (BTPA)₂ , and Cu₃ (TPTC)₂ MOF films were synthesized on Cu foil with the same strategy, which confirmed the universality of the proposed method. This controllable EC method can be effectively applied to the industrial-scale production of 2D MOF films on Cu foil.