Search

Designing polymers with high intrinsic thermal conductivity (TC) is critically important for the thermal management of organic electronics and photonics. However, this is a challenging task owing to the diversity of the chemical space and the barriers to advanced synthetic experiments/characterization techniques for polymers. In this Tutorial, the fundamentals and implementation of combining classical molecular dynamics simulation and machine learning (ML) for the development of polymers with high TC are comprehensively introduced. We begin by describing the core components of a universal ML framework, involving polymer data sets, property calculators, feature engineering, and informatics algorithms. Then, the process of constructing interpretable regression algorithms for TC prediction is introduced, aiming to extract the underlying relationships between microstructures and TCs for polymers. We also explore the design of sequence-ordered polymers with high TC using lightweight and mainstream active learning algorithms. Lastly, we conclude by addressing the current limitations and suggesting potential avenues for future research on this topic. [ABSTRACT FROM AUTHOR]

In this study, analytical models for space charge limited current (SCLC) transport in a porous (or disordered) trap-limited dielectric cylindrical configuration are developed. The method used in this paper is first verified by reproducing the well-known analytical results for planar cases developed decades ago based on the traditional approach. By considering the porous solid as a fractional object characterized by a parameter α ≤ 1 , we formulate its fractional capacitance and determine the SCLC transport by using the transit time approach. At α = 1 , it will recover the well-known Mott–Gurney law and Mark–Helfrich law for trap-free and trap-limited cases, respectively. For cylindrical geometry, our findings show an analytical form that is not available from the traditional methods. We anticipate that the proposed analytical model will serve as a useful tool for characterizing the current–voltage measurements in SCLC transport in dielectric breakdown and organic electronics, where spatial porosity of the materials is inevitable. The introduced fractional parameter α extracted from such characterization can facilitate the quantitative determination of the relationship between spatial porosity and charge mobility. [ABSTRACT FROM AUTHOR]

In pursuing sustainable technologies, organic electronic-based materials have witnessed remarkable progress, with polyfluorene (PF) among the blue light-emitting polymers garnering significant attention. PF, renowned for its remarkable light absorption and exceptional optoelectronic properties, exhibits great potential for various applications including display technologies, solar cells, lasers and transistors. Nonetheless, the diverse phases in PF significantly affect the performance of optoelectronic devices, predominantly due to the coexistence of different conformations in thin films, while promising, PF confronts hurdles related to stability and degradation during operation, leading to spectral changes and colour purity issue. Since the early 1990s, various studies have been devoted by researchers to determine the chemical changes in the PF chain and its functional groups after being subjected to different types of degradation with the aim of controlling and retarding the decomposition process. Another alternative strategy is to promote the formation of β-phase in PF, which is characterised by well-ordered conformation. This review aims to provide a comprehensive overview of PF degradation behaviour, modes and mechanisms. Various approaches to delay and suppress PF degradation are discussed. Meanwhile, the role of the β-phase in suppressing PF degradation and enhancing optoelectronic applications has also been highlighted. Thus, scientists are diligently attempting to enhance the formation and stability of the β-phase to improve the performance of optoelectronic applications. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: In the last few years, organic solar cells (OSCs) have made significant progress in photovoltaic performance, mainly due to the innovative development of active layer materials, especially Y‐series and related derivatives as acceptors which have become the key factor that boosts the power conversion efficiency. Recently, to achieve high‐performance OSCs, an emerging molecular design strategy of applying flexible alkyl units as linkers to construct non‐fully conjugated acceptors has been developed and addressed great attention. This review highlights the non‐fully conjugated photovoltaic materials with Y‐series backbone that enable high‐performance OSCs. Impressive OSCs have been achieved by some representative non‐fully conjugated material systems. The related molecular design strategies are discussed in detail. Finally, a brief summary and future prospect are provided in advancing the non‐fully conjugated photovoltaic materials with Y‐series backbone towards the brighter future. Key Scientists: [ABSTRACT FROM AUTHOR]

The emergence of stretchable electronic technology has led to the development of many industries and facilitated many unprecedented applications, owing to its ability to bear various deformations. However, conventional solid elastomer substrates and encapsulation can severely restrict the free motion and deformation of patterned interconnects, leading to potential mechanical failures and electrical breakdowns. To address this issue, we propose a design strategy of porous elastomer substrate and encapsulation to improve the stretchability of serpentine interconnects in island-bridge structures. The serpentine interconnects are fully bonded to the elastomer substrate, while segments above circular pores remain suspended, allowing for free deformation and a substantial improvement in elastic stretchability compared to the solid substrates. The pores ensure unimpeded interconnect deformations, and moderate porosity provides support while maintaining the initial planar state. Compared to conventional solid configurations, finite element analysis (FEA) demonstrates a substantial enhancement of elastic stretchability (e.g. ≈9 times without encapsulation and ≈ 7 times with encapsulation). Uniaxial cyclic loading fatigue experiments validate the enhanced elastic stretchability, indicating the mechanical stability of the porous design. With its intrinsic advantages in permeability, the proposed strategy has the potential to offer insightful inspiration and novel concepts for advancing the field of stretchable inorganic electronics. [ABSTRACT FROM AUTHOR]

Dynamic Covalent Chemistry, consisting in the use of dynamic covalent bonds (DCBs) to create complex objects by working at the thermodynamic equilibrium, has undeniable advantages for the preparation of conjugated systems with tailored optoelectronic properties for organic electronics. Chemists can combine simple building blocks with simple functional groups of appropriate geometry, structure and stoichiometry to build multidimensional conjugated architectures. Dynamic covalent reactions are often precious metal‐free, generate little to no side products and are very efficient. DCBs however afford sensitive materials, and consequently a balance needs to be found between the ease of synthesis, the stability and the performances. The dynamicity of the target materials hence can considerably reduce their applicability in organic electronics where strongly stable materials are needed, but opens the door to stimuli‐responsive behaviour and recyclability. A way to overcome dynamicity issues is to lock DCBs, but often at the cost of decreased conjugation. In this review, we will highlight how DCBs are employed to prepare functional optoelectronically active materials, such as discrete molecules, polymers or covalent organic frameworks, applied in fields ranging from organic light‐emitting diodes and solar cells to organic batteries and transistors. We will also discuss their limitations, benefits and the current challenges to overcome. [ABSTRACT FROM AUTHOR]

Understanding the relationship between morphology and charge transport capability in organic thin films is vital for advancements in organic electronics. However, accurately predicting charge mobility in these films is challenging due to the extensive evaluations of transfer integral required. To address this challenge, transfer learning techniques are employed to develop machine learning models capable of efficiently and accurately calculating transfer integrals in organic thin films with grain boundaries and polymorphs. Through machine learning‐assisted multiscale simulations of charge transport, the impact of solution shearing conditions is investigated on the morphology and mobility of organic thin films. The findings reveal that shearing‐induced molecular orientation and pre‐aggregation have a significant influence on film morphology, and a moderate shearing speed combined with a suitable solvent promotes the formation of extended transport networks, leading to higher mobility. The utilization of transfer learning‐accelerated simulation techniques opens up new possibilities for exploring the relationship between solution‐processing conditions, morphology, and charge transport properties of organic thin films. This research provides valuable insights that can be applied to optimize solution‐processing techniques in organic electronics. [ABSTRACT FROM AUTHOR]

Cellulose is a natural polymer with great properties such as high optical transparency and mechanical strength, flexibility, and biodegradability. Hence, cellulose‐based foils are suitable for the replacement of synthetic polymers as substrate materials in organic electronics. This article reports the fabrication of ultrathin, free‐standing cellulose foils by spraying aqueous 2,2,6,6‐tetramethylpiperidine‐1‐oxyl‐nanocellulose (TEMPO) fibrils ink layer‐by‐layer on a hot substrate using a movable spray nozzle. The resulting foils are only 2 ± 1 µm in thickness with an average basis weight of 1.9 g m−2, which ranges in the same scale as the world's thinnest paper. The suitability of these ultra‐thin nanocellulose foils as a sustainable substrate material for organic electronic applications is demonstrated by testing the foils resistance against organic solvents. Furthermore, silver nanowires (AgNWs) and the blend poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) are integrated into the foils, and the foils are molded into 3D paper structures in order to create conductive, paper‐based building blocks for organic electronics. [ABSTRACT FROM AUTHOR]

Polymeric hybrid films, for their application in organic electronics, were produced from new ruthenium indanones in poly(methyl methacrylate) (PMMA) by the drop-casting procedure. Initially, the synthesis and structural characterization of the ruthenium complexes were performed, and subsequently, their properties as a potential semiconductor material were explored. Hence hybrid films in ruthenium complexes were deposited using PMMA as a polymeric matrix. The hybrid films were characterized by infrared spectrophotometry and atomic force microscopy. The obtained results confirmed that the presence of the ruthenium complexes enhanced the mechanical properties in addition to increasing the transmittance, favoring the determination of their optical parameters. Both hybrid films exhibited a maximum stress around 10.5 MPa and a Knoop hardness between 2.1 and 18.4. Regarding the optical parameters, the maximum transparency was obtained at wavelengths greater than 590 nm, the optical band gap was in the range of 1.73–2.24 eV, while the Tauc band gap was in the range of 1.68–2.17 eV, and the Urbach energy was between 0.29 and 0.50 eV. Consequently, the above comments are indicative of an adequate semiconductor behavior; hence, the target polymeric hybrid films must be welcomed as convenient candidates as active layers or transparent electrodes in organic electronics. [ABSTRACT FROM AUTHOR]

Acenes and Naphthalene Diimides (NDIs) stand as distinguished classes of organic compounds, each possessing unique and intriguing properties that have garnered significant attention across various scientific disciplines. Acenes, characterized by linearly fused aromatic rings, have captivated researchers due to their diverse electronic structures and promising applications in materials science. On the other hand, NDIs, known for their distinctive electron–accepting properties, exhibit remarkable versatility in fields ranging from organic electronics, supramolecular to spin chemistry. In this review, we navigate through the fascinating realms of both acenes and NDIs before converging our focus on the highly diverse and distinctive subgroup of NDI–annulated heterocyclic acenes. This potentially important subgroup, has emerged as a subject of intense investigation, encapsulating their fascinating synthesis, optical and electrochemical characteristics, and multifaceted applications that span the realms of chemistry, physics, and biology. Through the exploration of their synthetic strategies, unique properties, and diverse applications, this review aims to offer a comprehensive understanding of the pivotal role played by NDI‐based heterocyclic acenes in contemporary multidisciplinary research and technological innovation. [ABSTRACT FROM AUTHOR]

Conjugated polymers (CPs) with low crystallinity are promising candidates for application in organic thermoelectrics (OTEs), particularly in flexible devices, because the disordered structures of these CPs can effectively accommodate dopants and ensure robust resistance to bending. However, n‐doped CPs usually exhibit poor thermoelectric performance, which hinders the development of high‐performance thermoelectric generators. Herein, we report an n‐type CP (ThDPP‐CNBTz) comprising two acceptor units: a thiophene‐flanked diketopyrrolopyrrole and a cyano‐functionalized benzothiadiazole. ThDPP‐CNBTz shows a low LUMO energy level of below −4.20 eV and features low crystallinity, enabling high doping efficiency. Moreover, the dual‐acceptor design enhances polaron delocalization, resulting in good thermoelectric performance. After n‐doping, ThDPP‐CNBTz exhibits an average electrical conductivity (σ) of 50.6 S cm−1 and a maximum power factor (PF) of 126.8 μW m−1 K−2, which is among the highest values reported for solution‐processed n‐type CPs to date. Additionally, a solution‐processed flexible OTE device based on doped ThDPP‐CNBTz exhibits a maximum PF of 70 μW m−1 K−2; the flexible device also shows remarkable resistance to bending strain, with only a marginal change in σ after 600 bending cycles. The findings presented in this work will advance the development of n‐type CPs for OTE devices, and flexible devices in particular. [ABSTRACT FROM AUTHOR]

As transparent, flexible, and wearable organic electronics degrade under normal outdoor environmental conditions (e.g., water vapor, oxygen, and UV light) and extreme environments, including washing or rain, a customized encapsulation technology is required to improve device reliability. Herein, a simple process is presented for fabricating multifunctional hazy substrates (MFHSs) with excellent gas diffusion barrier (GDB), flexibility, UV reflectance, light scattering, and waterproof properties. First, a spiky polyethylene terephthalate (PET) surface is produced with 76.0% optical haze through ion‐beam treatment followed by the formation of a hydrophobic layer to achieve a waterproof effect (contact angle: 153.3°). Then, a multifunctional multibarrier film is fabricated based on a nano‐laminated distributed Bragg reflector and functional polymer on the functional PET substrate to serve as a GDB and UV filter. This multibarrier film has excellent mechanical and chemical stabilities, in addition to having a water vapor transmission rate of 10−6 g m−2 day−1 and UV transmittance of <3%. The so‐fabricated MFHS not only increases the device efficiency by 73% but also enables a highly flexible and environmentally stable organic light–emitting diode. The surface treatment and encapsulation technologies developed in this study are expected to increase the lifetime of organic devices and facilitate high outdoor usability. [ABSTRACT FROM AUTHOR]

Conjugated polymers (CPs) with low crystallinity are promising candidates for application in organic thermoelectrics (OTEs), particularly in flexible devices, because the disordered structures of these CPs can effectively accommodate dopants and ensure robust resistance to bending. However, n‐doped CPs usually exhibit poor thermoelectric performance, which hinders the development of high‐performance thermoelectric generators. Herein, we report an n‐type CP (ThDPP‐CNBTz) comprising two acceptor units: a thiophene‐flanked diketopyrrolopyrrole and a cyano‐functionalized benzothiadiazole. ThDPP‐CNBTz shows a low LUMO energy level of below −4.20 eV and features low crystallinity, enabling high doping efficiency. Moreover, the dual‐acceptor design enhances polaron delocalization, resulting in good thermoelectric performance. After n‐doping, ThDPP‐CNBTz exhibits an average electrical conductivity (σ) of 50.6 S cm−1 and a maximum power factor (PF) of 126.8 μW m−1 K−2, which is among the highest values reported for solution‐processed n‐type CPs to date. Additionally, a solution‐processed flexible OTE device based on doped ThDPP‐CNBTz exhibits a maximum PF of 70 μW m−1 K−2; the flexible device also shows remarkable resistance to bending strain, with only a marginal change in σ after 600 bending cycles. The findings presented in this work will advance the development of n‐type CPs for OTE devices, and flexible devices in particular. [ABSTRACT FROM AUTHOR]

Layered (2D) perovskites are an emerging attractive 2D system with enhanced stability to ambient conditions as opposed to their highly unstable three dimensional bulk counterpart. Their uniquely tuneable optical and electrical properties are underpinning a surge of interest in 2D‐photovoltaics. So far, the development of nano‐scale integrated opto‐electronic 2D perovskite devices remains nearly unexplored since they have generally been found to be incompatible with standard top‐down semiconductor nano‐fabrication technologies. Here, following the synthesis of solvent‐stable 2D‐fluorinated phenethylammonium lead iodide perovskite (F‐PEA)2PbI4 (F‐PEAI), planar photodetectors entirely fabricated in atmosphere is demonstrated, exhibiting figures of merit rivalling those of commercial silicon photodiodes. A record large room temperature detectivity (>5 × 1017 Jones), a fast time photoresponse (rise time 1.5 ns), an extraordinarily large linear dynamic range (228 dB), as well as a photo‐responsivity of ≈ 1100 AW−1 are demonstrated for devices on a range of substrates including flexible wearable media without the need for any planarization or any atomically thin dielectric, in stark contrast to other 2D semiconductors. Finally, the suitability of nano‐scale 2D F‐PEAI photodetector arrays with sub‐wavelength pixel size of just 100 nm of use for high definition imaging is demonstrated. [ABSTRACT FROM AUTHOR]

Stretchable inorganic electronics have been of growing interest over the past decades due to their various attractive potential applications. The island-bridge structure is the most widely used structural design, where rigid inorganic devices (islands) and interconnects (bridges) are attached to an elastomer substrate, and large deformations in the structure are accommodated by the large stretchability of the interconnects and the elastomer underneath them. Due to the large modulus mismatch of more than five orders of magnitude between the rigid island and elastomer substrate, there is a severe stress and strain concentration at the interface between the island and the substrate during large deformations, which may cause the interface fracture and delamination. In this work, the analytical solution of the interfacial shear and peel stress between the island and the substrate is derived to reveal the mechanism of interface fracture and agrees well with finite element analysis (FEA) results. A simple porous partition substrate design strategy is proposed to alleviate this stress and strain concentration at the boundary of the interface, where the porous region can undergo larger deformation due to the reduced stiffness of the material. FEA obtains the key parameters affecting the pore layout. The digital image correlation (DIC) experiment verifies the design strategy. The results show that, compared to the solid substrate, the porous partition substrate strategy can significantly reduce the maximum normal strain of the substrate around the island, thus effectively reducing the risk of structural interface failure. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The investigation of n‐type doping holds a significant interest for the application of thermoelectrics. Herein, the doping of an indandione‐terminated compound Q‐4F with a singlet open‐shell ground state was studied using two n‐dopants N‐DMBI and LCV. Both of these two dopants can effectively dope Q‐4F due to the large offset between the singly occupied molecular orbital (SOMO) of dopants and the lowest unoccupied molecular orbital (LUMO) of Q‐4F. N‐DMBI has a higher doping ability than LCV as demonstrated by the UV‐vis‐NIR and EPR measurements. However, in comparison to N‐DMBI doped Q‐4F, LCV doped system exhibits much higher electrical conductivity and power factor due to its unperturbed molecular packing and favorable morphology after doping. The optimal conductivity of LCV doped Q‐4F is 7.16 × 10–2 ± 0.16 S·cm–1 and the highest power factor reaches 12.3 ± 0.85 μW·m–1·K–2. These results demonstrate that the modulation of n‐dopants is a powerful strategy to balance the doping efficiency and microstructure toward a maximum thermoelectric performance. [ABSTRACT FROM AUTHOR]

The construction of high-performance n-type semiconductors is crucial for the advancement of organic electronics. As an attractive n-type semiconductor, molecular systems based on perylene diimide derivatives (PDIs) have been extensively investigated over recent years. Owing to the fascinating aggregated structure and high performance, S-heterocyclic annulated PDIs (SPDIs) are receiving increasing attention. However, the relationship between the structure and the electrical properties of SPDIs has not been deeply revealed, restricting the progress of PDI-based organic electronics. Here, we developed two novel SPDIs with linear and dendronized substituents in the imide position, named linear SPDI and dendronized SPDI, respectively. A series of structural and property characterizations indicated that linear SPDI formed a long-range-ordered crystalline structure based on helical supramolecular columns, while dendronized SPDI, with longer alkyl side chains, formed a 3D-ordered crystalline structure at a low temperature, which transformed into a hexagonal columnar liquid crystal structure at a high temperature. Moreover, no significant charge carrier transport signal was examined for linear SPDI, while dendronized SPDI had a charge carrier mobility of 3.5 × 10−3 cm2 V−1 s−1 and 2.1 × 10−3 cm2 V−1 s−1 in the crystalline and liquid crystalline state, respectively. These findings highlight the importance of the structure–function relationship in PDIs, and also offer useful roadmaps for the design of high-performance organic electronics for down-to-earth applications. [ABSTRACT FROM AUTHOR]

The title compound was synthesized by Ullmann cross‐coupling in low yield as the first representative of [n]phenylene containing hydrocarbon and fluorocarbon rings. Stille/Suzuki‐Miyaura cross‐coupling reactions, as well as substitution of fluorine in suitable starting compounds, failed to give the same product. The geometric and electronic structures of the title compound were studied by X‐ray diffraction, cyclic voltammetry and density functional theory calculations, together with Hirshfeld surface and reduced density gradient analyses. The crystal structure features head‐to‐tail π‐stacking and other fluorine‐related secondary bonding interactions. From the nucleus‐independent chemical shifts descriptor, the four‐membered ring of the title compound is antiaromatic, and the six‐membered rings are aromatic. The Janus molecule is highly polarized; and the six‐membered fluoro‐ and hydrocarbon rings are Lewis π‐acidic and π‐basic, respectively. The electrochemically‐generated radical cation of the title compound is long‐lived as characterized by electron paramagnetic resonance, whereas the radical anion is unstable in solution. The title compound reveals electrical properties of an insulator. On expanding its molecular scaffold towards partially fluorinated [n]phenylenes (n≥2), the properties presumably can be transformed into those of semiconductors. In this context, the title compound is suggested as a prototype scaffold for ambipolar materials for organic electronics and spintronics. [ABSTRACT FROM AUTHOR]

Heterocycles that pair main group elements and nitrogen are extremely important within the π‐conjugated heterocycles research community. Compared to the vast number of boron‐nitrogen heterocycles, those that include phosphorus are less common. Furthermore, the use of phosphorus‐nitrogen triple bonds of any type to prepare such compounds is unprecedented. Here, we pair pyridyl hydrazonide ligands with phosphadiazonium cations and demonstrate that the chelated Mes*NP group is directly implicated in the photophysical and redox properties observed for the resulting heterocycles. In doing so, we introduce a novel building block for the production of phosphorus‐containing heterocycles that could find use in small molecule activation and catalysis or as the functional component of emerging organic electronics. [ABSTRACT FROM AUTHOR]

Supramolecular electronics exploits the distinctive features stemming from noncovalent interactions, guiding the self‐assembly of molecules to craft materials endowed with customized electronic functionalities. Hydrogen‐bonded materials, characterized by their capacity to establish dynamic and stable networks, introduce an extra dimension to the development of supramolecular electronic systems. This study presents a comparative analysis of two remarkably small semiconductors utilizing diketopyrrolopyrrole functionalized with urea units as hydrogen‐bonding motifs, strategically positioned at opposing ends of the conjugated core. We show how the subtle distinction in functionalization not only influences morphology and self‐assembly dynamics via hydrogen‐bonding and π‐π stacking formation, but also holds significant consequences for ultimate charge transport properties. Our observations into the interplay of noncovalent interactions provide valuable insights and strategic pathways for the design of novel materials with enhanced electronic characteristics. [ABSTRACT FROM AUTHOR]

Recently, solution‐processable n‐doped poly(benzodifurandione) (n‐PBDF) has been made through in‐situ oxidative polymerization and reductive doping, which exhibited exceptionally high electrical conductivities and optical transparency. The discovery of n‐PBDF is considered a breakthrough in the field of organic semiconductors. In the initial report, the possibility of structural defect formation in n‐PBDF was proposed, based on the observation of structural isomerization from (E)‐2H,2′H‐[3,3′‐bibenzofuranylidene]‐2,2′‐dione (isoxindigo) to chromeno[4,3‐c]chromene‐5,11‐dione (dibenzonaphthyrone) in the dimer model reactions. In this study, we present clear evidence that structural isomerization is inhibited during polymerization. We reveal that the dimer (BFD1) and the trimer (BFD2) can be reductively doped by several mechanisms, including hydride transfer, forming charge transfer complexes (CTC) or undergoing an integer charge transfer (ICT) with reactants available during polymerization. Once the hydride transfer adducts, the CTC, or the ICT product forms, structural isomerization can be effectively prevented even at elevated temperatures. Our findings provide a mechanistic understanding of why isomerization‐derived structural defects are absent in n‐PBDF backbone. It lays a solid foundation for the future development of n‐PBDF as a benchmark polymer for organic electronics and beyond. [ABSTRACT FROM AUTHOR]

The prospect of large-scale production of low-cost electronic devices is a driving factor behind the recent interest in printed organic electronics. However, the upscaling of laboratory organic electronic devices is extremely challenging since it requires the adaptation of materials and fabrication processes optimized for the small scale to industrial manufacturing techniques, such as roll-to-roll printing. Here, we demonstrate the fabrication of all-printed organic biosensors at the pilot production scale for use in the detection of glucose. By translating device architecture and operation, as well as electrode design and ink formulations of previously reported laboratory-scale glucose sensors to industrial printing and coating processes, we demonstrate sub-millimolar sensitivity to glucose in fully printed devices in a process which is now scalable to commercial production quantities. This Letter highlights the significant challenges associated with developing upscaled printed organic electronic biosensors and the approaches needed to address them. [ABSTRACT FROM AUTHOR]

Recently, solution‐processable n‐doped poly(benzodifurandione) (n‐PBDF) has been made through in‐situ oxidative polymerization and reductive doping, which exhibited exceptionally high electrical conductivities and optical transparency. The discovery of n‐PBDF is considered a breakthrough in the field of organic semiconductors. In the initial report, the possibility of structural defect formation in n‐PBDF was proposed, based on the observation of structural isomerization from (E)‐2H,2′H‐[3,3′‐bibenzofuranylidene]‐2,2′‐dione (isoxindigo) to chromeno[4,3‐c]chromene‐5,11‐dione (dibenzonaphthyrone) in the dimer model reactions. In this study, we present clear evidence that structural isomerization is inhibited during polymerization. We reveal that the dimer (BFD1) and the trimer (BFD2) can be reductively doped by several mechanisms, including hydride transfer, forming charge transfer complexes (CTC) or undergoing an integer charge transfer (ICT) with reactants available during polymerization. Once the hydride transfer adducts, the CTC, or the ICT product forms, structural isomerization can be effectively prevented even at elevated temperatures. Our findings provide a mechanistic understanding of why isomerization‐derived structural defects are absent in n‐PBDF backbone. It lays a solid foundation for the future development of n‐PBDF as a benchmark polymer for organic electronics and beyond. [ABSTRACT FROM AUTHOR]

Neuromorphic computing offers the opportunity to curtail the huge energy demands of modern artificial intelligence (AI) applications by implementing computations into new, brain‐inspired computing architectures. However, the lack of fabrication processes able to integrate several computing units into monolithic systems and the need for new, hardware‐tailored training algorithms still limit the scope of application and performance of neuromorphic hardware. Recent advancements in the field of organic transistors present new opportunities for neuromorphic systems and smart sensing applications, thanks to their unique properties such as neuromorphic behavior, low‐voltage operation, and mixed ionic‐electronic conductivity. Organic neuromorphic transistors push the boundaries of energy efficient brain‐inspired hardware AI, facilitating decentralized on‐chip learning and serving as a foundation for the advancement of closed‐loop intelligent systems in the next generation. The biocompatibility and dual ionic‐electronic conductivity of organic materials introduce new prospects for biointegration and bioelectronics. Their ability to sense and regulate biosystems, as well as their neuro‐inspired functions can be combined with neuromorphic computing to create the next‐generation of bioelectronics. These systems will be able to seamlessly interact with biological systems and locally compute biosignals in a relevant matter. [ABSTRACT FROM AUTHOR]

In the literature, PDIs have been shown to demonstrate extensive applications in the area of organic electronics due to their ability to act as n-type semiconductors. PDIs have been applied in a wide range of electronic devices, including energy storage devices. To fit in these applications, we have modified the valine-terminated PDI core by substituting groups, viz. phenoxy, 4-methoxy phenoxy, and 3,4-dimethoxy phenoxy groups, at bay positions to fine-tune their HOMO-LUMO levels. In this paper, a series of conjugation-extended 1,7-, 1,6- and 1,6,7-regioisomers of Val-PDIs were synthesized, and 1,6,7-PDIs were removed by utilizing the Soxhlet extraction technique used for the first time. The 1,7- and 1,6-PDIs were separated by repeated crystallization and their structural characterization was performed using FTIR, ¹H NMR, 13C NMR, and HRMS. Further, the structures of as-synthesized PDIs were optimized by DFT calculations using the B3LYP approach with a 6-31+G(d,p) basis set, and the electronic transitions were visualized by analyzing natural transition orbitals (NTO). The photophysical properties of the highly soluble bay-substituted PDIs were evaluated using UV-Visible and fluorescence spectroscopic techniques in organic solvents ranging from non-polar to polar. Furthermore, their relative polarities in the ground vs. excited state were determined by employing the Lippert-Mataga relations. The electrochemical investigations of PDIs were done using cyclic voltammetry to evaluate their redox behavior. In addition to their unique structural relationship, 1,7- and 1,6-regioisomers revealed intriguing optoelectronic properties. Finally, symmetric supercapacitors (SSCs) were developed by exploiting the regioisomerically pure 1,7- and 1,6-disubstituted PDIs as electrode materials. The as-fabricated PDIs/GF electrodes were optimized in a two-electrode SC device given their electrochemical performance. Two of the PDIs, viz. M1 and D1, demonstrated good results of specific capacitances, i.e. 59.41 and 23.60 Fg-1 respectively, in the SSC devices. [ABSTRACT FROM AUTHOR]

The doping levels of conjugated polymers significantly influence their conductivity, energetics, and optical properties. Recently, a highly conductive n‐doped polymer called poly (3,7‐dihydrobenzo[1,2‐b:4,5‐b′]difuran‐2,6‐dione) (poly(benzodifurandione), n‐PBDF) is discovered, opening new possibilities for n‐type conducting polymers in printed electronics and other fields. Controlling the doping level of n‐PBDF is of great interest due to its wide range of potential applications. Here controlled dedoping and redoping of n‐PBDF is reported and a mechanistic understating of such a process is provided. Dedoping occurs through electron transfer and proton capture, wherein the ionic dopants, tris(4‐bromophenyl)ammoniumyl hexachloroantimonate (Magic Blue), exhibit efficient proton capture ability and stronger interaction with n‐PBDF, resulting in high dedoping efficiency. Moreover, chemically dedoped PBDF can be redoped using various proton‐coupled electron transfer agents. By manipulating the doping levels of n‐PBDF thin films, ranging from highly doped to dedoped states, the system demonstrates controllable conductivity in five orders of magnitude, adjustable optical properties, and energetics. As a result, these characteristics demonstrate the potential applications of n‐PBDF in organic electrochemical transistors and thermoelectrics. [ABSTRACT FROM AUTHOR]

Organic semiconductor small molecules and polymers often incorporate heteroatoms into their chemical structures to affect the electronic properties of the material. A particular design philosophy has been to use these heteroatoms to influence torsional potentials, since the overlap of adjacent π‐orbitals is most efficient in planar systems and is critical for charge delocalization in these systems. Since these design rules became popular, the messages from the earlier works have become lost in a sea of reports of “conformational locks”, where the non‐covalent interactions have relatively small contributions to planarizing torsional potentials. Greater influences can be found in the stabilization by extended conjugation, consideration of steric repulsion, and the interactions involving solubilizing chains and neighboring molecules or polymer chains in condensed phases. [ABSTRACT FROM AUTHOR]

Ultra‐long room temperature phosphorescence (URTP) materials are extremely promising for applications in organic electronics. Creating materials with controlled photophysics to achieve this, however, is difficult due to the challenges in filling up and stabilizing the sensitive triplet excited states at ambient temperature. Herein, triplet excitons are harvested by an intuitively designed structurally simple organic phosphor in water under ambient conditions by using supramolecular host–guest chemistry with cucurbituril‐7 (CB7) and sodium dodecyl sulphate (SDS), a negatively charged surfactant, with high photoluminescence (PL) quantum yields (PLQYs) (69% and 73% for CB7 and SDS, respectively) and phosphorescence lifetimes (12.52 and 12.42 ms for CB7 and SDS, respectively). A protective polyvinyl alcohol (PVA) film successfully controls the afterglow emission, excited state lifetime as well as PLQY in a single organic phosphor (CzPy24+). While a 1% concentration of CzPy24+ in the PVA film shows blue phosphorescence with 78.82% PLQY having a lifetime of 1.9 s, a 5% of CzPy24+ addition shows a green afterglow with 67.52% PLQY and a lifetime of 1.3 s. Similarly, yellow afterglow is achieved on adding 20% CzPy24+ to the PVA film with a PLQY of 40.88%. The findings are promising and helpful in constructing tunable phosphors for suitable applications. [ABSTRACT FROM AUTHOR]

The morphology of organic films plays a pivotal role in determining the performance of transistor devices. While the dip-coating technique is capable of producing highly oriented organic films, it often encounters challenges such as limited coverage and the presence of defects in gaps between strips, adversely affecting device performance. In this study, we address these challenges by increasing solution viscosity through the incorporation of a substantial proportion of dielectric polymers, thereby enhancing the participation of additional molecules during the film formation process when pulled up. This method produces continuous and oriented organic films with a notable absence of gaps, significantly improving the carrier mobility of transistor devices by more than twofold. Importantly, the fabricated devices exhibit remarkable reliability, showing no hysteresis even after 200 cycles of measurement. Furthermore, the current and threshold voltages of the devices demonstrate exceptional stability, maintaining steady after 10,000 s of bias measurement. This approach provides a solution for the cost-effective and large-scale production of organic transistors, contributing significantly to the advancement of organic electronics. [ABSTRACT FROM AUTHOR]

Since the first applications of nanohoops in organic electronics appear promising, the time has come to go deeper into their rational design in order to reach high‐efficiency materials. To do so, systematic studies dealing with the incorporation of electron‐rich and/or electron‐poor functional units on nanohoops have to be performed. Herein, the synthesis, the electrochemical, photophysical, thermal, and structural properties of two [4]cyclo‐2,7‐carbazoles, [4]C‐Py‐Cbz, and [4]C‐Pm‐Cbz, possessing electron‐withdrawing units on their nitrogen atoms (pyridine or pyrimidine) are reported. The synthesis of these nanohoops is first optimized and a high yield above 50% is reached. Through a structure‐properties relationship study, it is shown that the substituent has a significant impact on some physicochemical properties (eg HOMO/LUMO levels) while others are kept unchanged (eg fluorescence). Incorporation in electronic devices shows that the most electrically efficient Organic Field‐Effect transistors are obtained with [4]C‐Py‐Cbz although this compound does not present the best‐organized semiconductor layer. These experimental data are finally confronted with the electronic couplings between the nanohoops determined at the DFT level and have highlighted the origin in the difference of charge transport properties. [4]C‐Py‐Cbz has the advantage of a more 2D‐like transport character than [4]C‐Pm‐Cbz, which alleviates the impact of defects and structural organization. [ABSTRACT FROM AUTHOR]

2,9‐ and 2,10‐diphenylpentacene were synthesized by direct C−H borylation of ketal‐protected pentacene, followed by halodeboronation, resolution of the dihalo isomers, Suzuki arylation, cleavage of the ketals and decarbonylation in the solid state. They were studied as main active components in organic field effect transistors (OFETs). Diphenyl substitution of pentacene affects the unit cell dimensions only slightly, preserving a face to edge molecular packing in the first layers of thin films evaporated on SiO2 substrates. Both isomers self‐assemble into nanoribbons during the thin film growth upon vapor deposition. The similarity between the surface induced phases of the 2,9‐isomer and unsubstituted pentacene leads to similar 4‐probe hole mobilities, i. e. 0.13 cm2 V−1 s−1 for the former. Whereas 2,9‐disubstitution thus does essentially preserve the thin film characteristics of unsubstituted pentacene, 2,10‐disubstitution is detrimental to the molecular ordering in the thin films and therefore to the field effect mobility which is only 0.07 cm2 V−1 s−1. The known strong enhancement of field effect mobility observed upon diphenyl substitution of anthracene can thus not be emulated analogously with pentacene. [ABSTRACT FROM AUTHOR]

This work shows the structural, thermogravimetric, optical, and electrochemical properties of boron subphthalocyanine chloride (B-subPc-Cl) as organic electronic material. The Fullprof Suite program and Rietveld analysis were used to refine and index the crystal structure of B-subPc-Cl. The thermogravimetric analysis (TGA) and the differential thermogravimetric analysis (dTG) were used to study the kinetic thermogravimetric factors using the Horowitz-Metzger's and Coats-Redfern methods. The absorption spectra of B-subPc-Cl contain two strong absorption bands (Soret-like band and Q-like band). The oscillator strength and electrical dipole strength were estimated by using a Gaussian fitting of the molar absorptivity (emolar) of the B-subPc-Cl. The HOMO-LUMO and the band gap of B-subPc-Cl were calculated by using cyclic voltammetry measurement. Details of the UV-Vis - NIR absorption spectra and optical band gap for B-subPc-Cl are also provided. Density-functional theory (DFT) method has been utilized to obtain geometrically optimized structure for the studied compound. The theoretical calculations agreed with the experimental results. The obtained results point out the prospects of BsubPc-Cl for the organic electronic applications. [ABSTRACT FROM AUTHOR]

Polymerization of small molecule acceptors (PSMAs) has been proved to be an effective strategy to design polymer acceptors. DPP-based PSMAs of P(IDIC-2TDPPEh) employing double electron-withdrawing building block IDIC and thiophene-flanked diketopyrrolopyrrole were well designed and prepared. The all-polymer solar cells employed P(IDIC-2TDPPEh) as acceptor and PBDB-T as donor performed a PCE of 1.57%. This work highly broadens the potential applications of DPP-based PSMAs in the fields of organic electronics. [ABSTRACT FROM AUTHOR]

The increasing amount of electronic exerts a profound impact on both the environment and human health. Looking forward, it is imperative to develop electronic products that can degrade under mind condition, which largely relies on the development of degradable organic semiconductors (OSCs). Yet, designing degradable OSCs with decent electrical properties is challenging. In this study, two degradable n‐type OSCs based on a dynamic covalent C═C bond formed via the Knoevenagel condensation reaction are reported. The cleavage of Knoevenagel formed C═C bond through a retro‐Knoevenagel process imparts the degradability of these two OSCs in the weak base, particularly in the human‐friendly α‐amino acid of lysine. Meanwhile, the C═C bond formed by Knoevenagel reaction preserves optimal backbone planarity and good electron delocalization of the molecules. This, in turn, endows the OSCs with commendable electron transport performance, achieving an electron mobility of up to 0.57 cm2 V⁻¹ s⁻¹ in organic thin‐film transistors. This work provides a new insight into the molecular design strategy for the development of OSCs with degradability and good electrical properties. [ABSTRACT FROM AUTHOR]

TEMPO-containing conductive polymers are used in organic electronics due to their electrochemical properties. One of significant limitations in developing such materials is the structural modification by several TEMPO moieties. Here, we report a synthesis of the first-generation dendrimer containing two TEMPO fragments, bis(2,2,6,6-tetramethyl-1-(λ1-oxidaneyl)piperidin-4-yl) 3,3′-((2-hydroxyethyl)azanediyl)dipropionate, that can be implemented into a conductive polymer structure. The resulting product was characterized using 1H and 13C nuclear magnetic resonance spectroscopy (NMR) and high-resolution mass spectroscopy (HRMS). [ABSTRACT FROM AUTHOR]

Organic field effect transistors (OFETs), used in the fabrication of nano‐sensors, are one of the most promising devices in organic electronics because of their lightweight, flexible, and low fabrication cost. However, the numerical modeling of such OFETs is still in an early stage due to the minimal analytical as well as numerical models presented in the literature. This research aims to demonstrate an experimentally verified machine‐learning model by investigating an OFET with polyaniline as a p‐type organic semiconductor. OFET's threshold voltage, on/off current ratio, subthreshold swing, and device mobilities are studied as the primary output chiasmatic parameters. The random‐forest machine learning model has shown the criticality of the doping effect on turning the OFET to depletion mode, with positive threshold voltage, under doping higher than 5×1014$$ 5\times {10}^{14} $$ cm−3. Additionally, the study highlights the effectiveness of the gate oxide thickness in controlling the OFET threshold voltage. A 50 nm oxide thickness showed sufficiency to have a non‐depleted OFET operation. [ABSTRACT FROM AUTHOR]

We derive and investigate a stationary model for the electrothermal behavior of organic thin‐film devices including their electrical and thermal environment. Whereas the electrodes are modeled by Ohm's law, the electronics of the organic device itself is described by a generalized van Roosbroeck system with temperature‐dependent mobilities and using Gauss–Fermi integrals for the statistical relation. The currents give rise to Joule heat which together with the heat generated by the generation/recombination of electrons and holes in the organic device occur as source terms in the heat flow equation that has to be considered on the whole domain. The crucial task is to establish that the quantities in the transfer conditions at the interfaces between electrodes and the organic semiconductor device have sufficient regularity. Therefore, we restrict the analytical treatment of the system to two spatial dimensions. We consider layered organic structures, where the physical parameters (total densities of transport states, reference energy levels , disorder parameter, basic mobilities, activation energies, relative dielectric permittivity, heat conductivity) are piecewise constant, and we work in a W1,q$W^{1,q}$ setting for some q>2$q>2$. We prove the existence of weak solutions using Schauder's fixed point theorem and a regularity result for strongly coupled systems with nonsmooth data and mixed boundary conditions that is verified by Caccioppoli estimates and a Gehring‐type lemma. [ABSTRACT FROM AUTHOR]

Molecular design is crucial for endowing conjugated polymers (CPs) with unique properties and enhanced electronic performance. Introducing Hydrogen‐bonding (H‐bonding) into CPs has been a broadly exploited, yet still emerging strategy capable of tuning a range of properties encompassing solubility, crystallinity, electronic properties, solid‐state morphology, and stability, as well as mechanical properties and self‐healing properties. Different H‐bonding groups can be utilized to tailor CPs properties based on the applications of interest. This review provides an overview of classes of H‐bonding CPs (assorted by the different H‐bond functional groups), the synthetic methods to introduce the corresponding H‐bond functional groups and the impact of H‐bonding in CPs on corresponding electronic and materials properties. Recent advances in addressing the trade‐off between electronic performance and mechanical durability are also highlighted. Furthermore, insights into future directions and prospects for H‐bonded CPs are discussed. [ABSTRACT FROM AUTHOR]

This study focuses on the synthesis and characterization of a series of conjugated porous polymers (CPPs) based on a 2,4,6‐tris(5‐ethynylthiophen‐2‐yl)‐1,3,5‐triazine (TT) core moiety. TT was coupled with several conjugated building blocks as comonomers, including naphthodithiophene, benzodithiophene, bithiophene, tetraphenyl porphyrin, azulene, and perylene diimide, utilizing the Sonogashira‐coupling reaction to produce narrow band gap (1.73–2.19 eV) CPPs. The solid‐state UV‐visible spectra demonstrated broad absorption in 350 nm to 900 nm region, indicating extended π‐conjugation in the polymers. The photophysical properties of the polymers have been tuned by the judicious choice of comonomer. The obtained CPPs exhibit excellent thermal stability, reaching as high as 500 °C, and porosity insights reveal dominance of mesopores and macropores. Morphological studies reveal that 2‐ethylhexyl substituted perylene diimide hinder the stacking amongst the polymeric backbone, resulting in featureless aggregates, whereas the cyclohexyl group on perylene diimide results in well‐defined nanofibrous morphology. These narrow band‐gap CPPs hold promise for applications in energy storage, organic electronics, photocatalysis and sensing technologies. [ABSTRACT FROM AUTHOR]

Boron‐ and nitrogen‐doped polycyclic aromatic hydrocarbons (B‐PAHs) have established a strong foothold in the realm of organic electronics. However, their catalytic potential remains largely untapped. In this study, we synthesise and characterise two bench stable B,N‐doped PAH derivatives based on a 1,4‐azaborinine motif. Most importantly, the anthracene derived structure is an efficient catalyst in the reduction of various carbonyls and imines. These results underscore the potential of B,N‐PAHs in catalytic transformations, setting the stage for deeper exploration in this chemical space. [ABSTRACT FROM AUTHOR]

Three small molecules consisting of thieno‐fused naphthalimide units connected via aromatic linkers were synthesized to study the effect of fused thiophene rings on the properties of naphthalimide‐based molecules. A protocol for the synthesis of thienonaphthalimide‐based molecules without prior preparation and use of thienonaphthalimide precursors and organoelement compounds (organolithium, organotin, or organoboron compounds) was developed. The protocol is based on double thienannulation of bis‐alkyne substrates with sodium sulfide. The thin‐film morphology, photophysical and electrochemical properties of the obtained small molecules were studied. Single‐layer non‐doped organic light‐emitting diodes based on fluorene‐bridged thienonaphthalimide dimer showed yellow emission with luminance of 2200 cd/m2, and current efficiency of 0.35 cd/A. Combination of transient electroluminescence and photo‐CELIV methods allowed to estimate electron and hole mobility in the synthesized compounds; both are in order of 10−6 cm2V−1 s−1. [ABSTRACT FROM AUTHOR]

Oxadiazoles, especially 1,3,4-oxadiazole scaffolds, stand among the foremost heterocyclic fragments with a broad spectrum of applications in diverse fields, including pharmacology, polymers, material science, and organic electronics, among others. In this comprehensive review, we summarize the pivotal synthetic strategies for 1,3,4-oxadiazole derivatives including dehydrogenative cyclization of 1,2-diacylhydrazines, oxidative cyclization of acylhydrazones, condensation cyclization, C-H activation of oxadiazole ring, decarboxylative cyclization and oxidative annulation along with plausible mechanisms. The set of 1,3,4-oxadiazoles selected from the literature and discussed herein epitomize the ease of synthesis as well as the possibility of linking π-conjugated groups; thereby encouraging the use of these molecules as important starting building blocks for a wide variety of fluorescent frameworks, particularly in the development of potential chemosensors. High photoluminescent quantum yield, excellent thermal and chemical stability, and the presence of potential coordination (N and O donor atoms) sites make these molecules a prominent choice for metal-ions sensors. An overview of selective metal-ion sensing, the detection limit along with the sensing mechanisms (photo-induced electron transfer, excited-state intramolecular proton transfer, and complex formation) is also included. [ABSTRACT FROM AUTHOR]

The incorporation of the vinylene motif into conjugated molecules notably elevates the HOMO level, augmenting both emissive and conductive properties while enhancing responsiveness to external stimuli. This study focuses on the regioselective C−H/C−H coupling of N‐vinylcarbazole with thiophenes, offering an efficient route to N‐vinylene‐incorporated conjugated molecules for the development of organic electronic materials. Traditional palladium‐catalyzed Fujiwara‐Moritani (FM) reactions proved ineffective for C−H alkenylation with N‐vinylcarbazole. In response, we have developed an iron‐catalyzed twofold alkenylation method for conjugated thiophenes with N‐vinylcarbazole, utilizing trimethylaluminum as the base and diethyl oxalate as the oxidant. This reaction occurs regioselectively at the C2−H (or C5−H) bond of the thiophenes and the terminal position of N‐vinylcarbazole. It also successfully produces short thiophene polymers end‐capped with N‐vinylcarbazole, demonstrating the potential for synthesizing polymeric donor materials. The enamine products exhibit blue‐to‐green emission, high fluorescence quantum yield, and visible light responsivity for stereo‐isomerization, indicating promising applications in organic electronics. [ABSTRACT FROM AUTHOR]

In recent decades, considerable attention has been focused on the design and development of surfaces with defined or tunable properties for a wide range of applications and fields. To this end, self-assembled monolayers (SAMs) of organic compounds offer a unique and straightforward route of modifying and engineering the surface properties of any substrate. Thus, alkane-based self-assembled monolayers constitute one of the most extensively studied organic thin-film nanomaterials, which have found wide applications in antifouling surfaces, the control of wettability or cell adhesion, sensors, optical devices, corrosion protection, and organic electronics, among many other applications, some of which have led to their technological transfer to industry. Nevertheless, recently, aromatic-based SAMs have gained importance as functional components, particularly in molecular electronics, bioelectronics, sensors, etc., due to their intrinsic electrical conductivity and optical properties, opening up new perspectives in these fields. However, some key issues affecting device performance still need to be resolved to ensure their full use and access to novel functionalities such as memory, sensors, or active layers in optoelectronic devices. In this context, we will present herein recent advances in π-conjugated systems-based self-assembled monolayers (e.g., push–pull chromophores) as active layers and their applications. [ABSTRACT FROM AUTHOR]

Synthetic insecticides are widely used against plant pest insects to protect the crops. However, many insecticides have poor selectivity and are toxic also to beneficial insects, animals, and humans. In addition, insecticide residues can remain on fruits for many days, jeopardizing food safety. For these reasons, a reusable, low‐cost electronic trap that can attract, detect, and identify, but attack only the pest while leaving beneficial insects unharmed could provide a sustainable, nature‐friendly replacement. Here, for the first time, research results are presented suggesting the great potential and compatibility of organic electronic devices and technologies with pest management. Electrical characterizations confirm that an insect's body has relatively high dielectric permittivity. Adaptive memcapacitor circuits can track the impedance change for insect detection. Other experiments show that printed polymer piezoelectric transducers on a plastic substrate can collect information about the weight and activity of insects for identification. The breakdown voltage of most insects´ integument is measured to be <200 V. Long channel organic transistors easily work at such high voltages while being safe to touch for humans thanks to their inherent low current. This feasibility study paves the way for the future development of organic electronics for physical pest control and biodiversity protection. [ABSTRACT FROM AUTHOR]

Aromatic amines are ubiquitous moieties in organic molecules and their direct functionalization is of great interest in many research areas due to their prevalence in pharmaceuticals and organic electronics. While several synthetic tools exist for the ortho‐ and para‐functionalization of anilines, the functionalization of the less reactive meta‐position is not easy to achieve with current methods. To date, the meta‐C−H arylation of aniline derivatives has been restricted to either the use of directing groups & templates, or their transformation into anilides & quaternary anilinium salts. Herein, we report the first general and efficient meta‐C−H‐arylation of non‐directed aniline derivatives via cooperative catalysis with a palladium–S,O‐ligand–norbornene system. The reaction proceeds under mild conditions with a wide range of aniline derivatives and aryl iodides, while being operationally simple and scalable. Our preliminary mechanistic investigation–including the isolation of several palladium complexes and deuterium experiments–reveal useful insights into the substituent‐effects of both the aniline‐substrate and the norbornene‐mediator during the meta‐C−H activation step. [ABSTRACT FROM AUTHOR]

Singlet fission (SF) is a potential avenue for augmenting the performance of silicon photovoltaics, but the scarcity of SF materials energy‐matched to silicon represents a barrier to the commercial realization of this technology. In this work, a molecular engineering approach is described to increase the energy of the S1 and T1 energy levels of diketopyrrolopyrrole derivatives such that the energy‐level requirements for exothermic SF and energy‐transfer to silicon are met. Time‐resolved photoluminescence studies show that the silicon‐matched materials are SF active in the solid state, forming a correlated triplet pair 1(TT) – a crucial intermediate in the SF process – as observed through Herzberg‐Teller emission from 1(TT) at both 77 K and room temperature. Transient electron paramagnetic resonance studies show that the correlated triplet pair does not readily separate into the unbound triplets, which is a requirement for energy harvesting by silicon. The fact that the triplet pair do not separate into free triplets is attributed to the intermolecular crystal packing within the thin films. Nevertheless, these results demonstrate a promising route for energy‐tuning silicon‐matched SF materials. [ABSTRACT FROM AUTHOR]

Aromatic amines are ubiquitous moieties in organic molecules and their direct functionalization is of great interest in many research areas due to their prevalence in pharmaceuticals and organic electronics. While several synthetic tools exist for the ortho‐ and para‐functionalization of anilines, the functionalization of the less reactive meta‐position is not easy to achieve with current methods. To date, the meta‐C−H arylation of aniline derivatives has been restricted to either the use of directing groups & templates, or their transformation into anilides & quaternary anilinium salts. Herein, we report the first general and efficient meta‐C−H‐arylation of non‐directed aniline derivatives via cooperative catalysis with a palladium–S,O‐ligand–norbornene system. The reaction proceeds under mild conditions with a wide range of aniline derivatives and aryl iodides, while being operationally simple and scalable. Our preliminary mechanistic investigation–including the isolation of several palladium complexes and deuterium experiments–reveal useful insights into the substituent‐effects of both the aniline‐substrate and the norbornene‐mediator during the meta‐C−H activation step. [ABSTRACT FROM AUTHOR]

In this research, two polymers of P1 and P2 based on monomers consisting of thiophene, 3,4-Ethylenedioxythiophene (EDOT) and diketopyrrolopyrrole (DPP) are designed and obtained via Stille coupling polycondensation. The material shows excellent coplanarity and structural regularity due to the fine planarity of DPP itself and the weak non-covalent bonding interactions existing between the three units. Two different lengths of non-conjugated side chains are introduced and this has an effect on the intermolecular chain stacking, causing the film absorption to display different characteristic properties. On the other hand, the difference in the side chains does not have a significant effect on the thermal stability and the energy levels of the frontier orbitals of the materials, which is related to the fact that the materials both feature extremely high conjugation lengths and specific molecular compositions. Microscopic investigations targeting the side chains provide a contribution to the further design of organic semiconductor materials that meet device requirements. Tests based on organic transistors show a slight difference in conductivity between the two polymers, with P2 having better hole mobility than P1. This study highlights the importance of the impact of side chains on device performance, especially in the field of organic electronics. [ABSTRACT FROM AUTHOR]

Oligomers and polymers consisting of multiple thiophenes are widely used in organic electronics such as organic transistors and sensors because of their strong electron-donating ability. In this study, a solution to the problem of the poor solubility of polythiophene systems was developed. A novel π-conjugated polymer material, PDPP-5Th, was synthesized by adding the electron acceptor unit, DPP, to the polythiophene system with a long alkyl side chain, which facilitated the solution processing of the material for the preparation of devices. Meanwhile, the presence of the multicarbonyl groups within the DPP molecule facilitated donor–acceptor interactions in the internal chain, which further improved the hole-transport properties of the polythiophene-based material. The weak forces present within the molecules that promoted structural coplanarity were analyzed using theoretical simulations. Furthermore, the grazing incidence wide-angle X-ray scanning (GIWAXS) results indicated that PDPP-5Th features high crystallinity, which is favorable for efficient carrier migration within and between polymer chains. The material showed hole transport properties as high as 0.44 cm2 V−1 s−1 in conductivity testing. Our investigations demonstrate the great potential of this polymer material in the field of optoelectronics. [ABSTRACT FROM AUTHOR]