Power conversion efficiency (PCE) has surpassed 10% for single junction organic solar cells (OSCs) mainly through the design and synthesis of novel donor materials, the optimization of film ...morphology and the evolution of the devices. However, the development of novel acceptor materials is relatively sluggish compared with the donor compounds. Nowadays, fullerene derivatives, such as PC
61
BM and PC
71
BM, are still the dominant acceptors due to their superior charge transporting properties. Unfortunately, these two acceptors suffer from some intrinsic shortcomings such as limited absorption, difficult functionalization, and high production cost. Therefore, developing novel non-fullerene acceptors that can overcome the above-mentioned disadvantages is highly desirable. As a matter of fact, research on non-fullerene acceptors has made considerable progress in the last two years and a highest PCE of around 12% has been achieved. In this review, we will summarize recent research progress in non-fullerene small molecule acceptors and compare these molecules' performances in OSCs employing the same donor materials. Moreover, the acceptors with excellent photovoltaic performance are highlighted and the reasons are elaborated. Finally, the implications and the challenges are proposed.
The power conversion efficiencies (PCEs) of non-fullerene small molecule acceptors based on different donors have been compared and summarized.
Recently, smart 2D covalent organic frameworks (COFs), combining the advantages of both inherent structure features and functional building blocks, have been demonstrated to show reversible changes ...in conformation, color, and luminescence in response to external stimuli. This review provides a summary on the recent progress of 2D COFs that are responsive to external stimuli such as metal ions, gas molecules, pH values, temperature, electricity, light, etc. Moreover, the responsive mechanisms and design strategies, along with the applications of these stimulus‐responsive 2D COFs in chemical sensors and photoelectronic devices are also discussed. It is believed that this review would provide some guidelines for designing novel single‐/multistimulus‐responsive 2D COFs with controllable responsive behaviors for advanced photoelectronic applications.
In this review, the recent process of stimulus‐responsive 2D covalent organic frameworks (COFs) is summarized. The responsive behaviors and design strategies of these smart 2D COFs under physical or chemical stimuli are well described. Moreover, their applications in chemical sensors and photoelectronic devices are also discussed.
Replacing the CH groups in the backbones of acenes with heteroatoms offers scientists greater opportunities to tune their properties, as the type, position, number, and the valence of the introduced ...heteroatoms have strong effects on the frontier orbital energy levels. When the heteroatoms are nitrogen atoms, all of the resulting materials are called azaacenes. Recently, the synthesis, structure, physical properties, and applications of azaacene derivatives have been intensively investigated. This review focuses on recent synthetic efforts (since 2013) toward making novel azaacenes as well as their potential applications beyond field-effect transistors (FETs) including organic light-emitting diodes (OLEDs), memory devices, phototransistors, solar cells, photoelectrical chemical cells, sensors, and conductors.
Organic cocrystals based on noncovalent intermolecular interactions (weak interactions) have aroused interest owing to their unpredicted and versatile chemicophysical properties and their ...applications. In this Minireview, we highlight recent research on organic cocrystals on reducing the aggregation‐caused quenching (ACQ) effect, tuning light emission, ferroelectricity and multiferroics, optical waveguides, and stimuli‐responsiveness. We also summarize the progress made in this field including revealing the structure–property relationships and developing unusual properties. Moreover, we provide a discussion on current achievements, limitations and perspectives as well as some directions and inspiration for further investigation on organic cocrystals.
Crystal set: This Minireview provides a summary on current research into organic cocrystals (reducing the aggregation‐caused quenching (ACQ) effect, tuning light emission, ferroelectricity, multiferroics, optical waveguides, and stimuli‐responsiveness), their limitations and perspectives as well as some directions and inspiration for further investigation.
Organic n‐type materials (e.g., fullerene derivatives, naphthalene diimides (NDIs), perylene diimides (PDIs), azaacene‐based molecules, and n‐type conjugated polymers) are demonstrated as promising ...electron transport layers (ETLs) in inverted perovskite solar cells (p–i–n PSCs), because these materials have several advantages such as easy synthesis and purification, tunable frontier molecular orbitals, decent electron mobility, low cost, good solubility in different organic solvents, and reasonable chemical/thermal stability. Considering these positive factors, approaches toward achieving effective p–i–n PSCs with these organic materials as ETLs are highlighted in this Review. Moreover, organic structures, electron transport properties, working function of electrodes caused by ETLs, and key relevant parameters (PCE and stability) of p–i–n PSCs are presented. Hopefully, this Review will provide fundamental guidance for future development of new organic n‐type materials as ETLs for more efficient p–i–n PSCs.
Organic n‐type materials as electron transport layers (ETLs) in inverted perovskite solar cells (p–i–n PSCs) have attracted many scientists' attention, not only because of their several advantages, including easy synthesis, tunable frontier molecular orbitals, decent electron mobility, and reasonable chemical/thermal stability, but also because of their ability to make large‐scale solution‐processing p–i–n PSCs possible.
Significant progress on upconversion‐nanoparticle (UCNP)‐based probes is witnessed in recent years. Compared with traditional fluorescent probes (e.g., organic dyes, metal complexes, or inorganic ...quantum dots), UCNPs have many advantages such as non‐autofluorescence, high chemical stability, large light‐penetration depth, long lifetime, and less damage to samples. This article focuses on recent achievements in the usage of lanthanide‐doped UCNPs as efficient probes for biodetection since 2014. The mechanisms of upconversion as well as the luminescence resonance energy transfer process is introduced first, followed by a detailed summary on the recent researches of UCNP‐based biodetections including the detection of inorganic ions, gas molecules, reactive oxygen species, and thiols and hydrogen sulfide.
Due to the unique advantages that upconversion‐nanoparticle (UCNP)‐based probes have compared to traditional probes, such as non‐autofluorescence, large light penetration depth, and less damage to samples, research in this field has increased rapidly over recent years. Recent progress (since 2014) on the usage of lanthanide doped UCNPs as efficient probes for biodetection of inorganic ions, gas molecules, reactive oxygen species, and thiols is presented.
Given that surfactants can control the shape and size of micro‐/nanoparticles, they should be able to direct the growth of bulk crystals. This Minireview summarizes recent developments in the ...application of surfactants for the preparation of new crystalline inorganic materials, including chalcogenides, metal–organic frameworks, and zeolite analogues. The roles of surfactants in different reaction systems are discussed.
Multifaceted media: Since surfactants can control the shape and size of micro‐/nanoparticles, they are also able to direct the growth of bulk crystals. Recent developments in the use of surfactants in the preparation of crystalline inorganic materials, including chalcogenides, metal–organic frameworks, and zeolite analogues, are summarized in this Minireview.
Covalent organic frameworks (COFs), connecting different organic units into one system through covalent bonds, are crystalline organic porous materials with 2D or 3D networks. Compared with ...conventional porous materials such as inorganic zeolite, active carbon, and metal‐organic frameworks, COFs are a new type of porous materials with well‐designed pore structure, high surface area, outstanding stability, and easy functionalization at the molecular level, which have attracted extensive attention in various fields, such as energy storage, gas separation, sensing, photoluminescence, proton conduction, magnetic properties, drug delivery, and heterogeneous catalysis. Herein, the recent advances in metal‐free COFs as a versatile platform for heterogeneous catalysis in a wide range of chemical reactions are presented and the synthetic strategy and promising catalytic applications of COF‐based catalysts (including photocatalysis) are summarized. According to the types of catalytic reactions, this review is divided into the following five parts for discussion: achiral organic catalysis, chiral organic conversion, photocatalytic organic reactions, photocatalytic energy conversion (including water splitting and the reduction of carbon dioxide), and photocatalytic pollutant degradation. Furthermore, the remaining challenges and prospects of COFs as heterogeneous catalysts are also presented.
Covalent organic frameworks (COFs) as a new type of organic porous materials have aroused great interest in the field of heterogeneous catalysis. Herein, the applications of metal‐free COFs in organic catalysis, photocatalysis, energy conversion, and pollutant degradation are systematically summarized. In addition, the main challenges in this area and the potential prospects for future work are also discussed.
The features of well-conjugated and planar aromatic structures make π-conjugated luminescent materials suffer from aggregation caused quenching (ACQ) effect when used in solid or aggregated states, ...which greatly impedes their applications in optoelectronic devices and biological applications. Herein, we reduce the ACQ effect by demonstrating a facile and low cost method to co-assemble polycyclic aromatic hydrocarbon (PAH) chromophores and octafluoronaphthalene together. Significantly, the solid photoluminescence quantum yield (PLQYs) for the as-resulted four micro/nanococrystals are enhanced by 254%, 235%, 474 and 582%, respectively. Protection from hydrophilic polymer chains (P123 (PEO
-PPO
-PEO
)) endows the cocrystals with superb dispersibility in water. More importantly, profiting from the above-mentioned highly improved properties, nano-cocrystals present good biocompatibility and considerable cell imaging performance. This research provides a simple method to enhance the emission, biocompatibility and cellular permeability of common chromophores, which may open more avenues for the applications of originally non- or poor fluorescent PAHs.
The electrochemical application of metal–organic frameworks and their derived materials for electrocatalytic applications have been briefly discussed in this mini-review.
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•The ...mechanism of HER, OER, ORR, CO2RR, and NRR are simply expounded.•The latest electrochemical application of MOF-based materials are briefly discussed.•The challenges and perspectives for MOF-based electrocatalysts have been provided.
Oxygen evolution reaction (OER), hydrogen evolution reaction (HER), oxygen reduction reaction (ORR), nitrogen reduction reaction (NRR), and carbon dioxide reduction reaction (CO2RR) are five major reactions in the progress, conversion, and storage of clean energy.Efficient electrocatalysts can be used to decrease the overpotential of these reactions and elevate practical applications of energy-related systems.Metal–organic frameworks (MOFs), via the modification of electrodes, provide new opportunities to develop green and sustainable energy systems and conduct fundamental research on electrocatalytic applications. Benefitting from the versatility of engineering and construction strategies, compositional/structural modification, high electrical conductivity, various high-density active sites, and the capability as precursors, MOFs and the derived materials are considered as efficient electrocatalysts. Based on those merits, the electrochemical application of MOFs and their derived materials for the five mentioned reactions are briefly discussed in this mini review. Furthermore, the challenges and perspectives for engineering MOF-based electrocatalysts are also provided.
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