Dual Function of the Third Component in Ternary Organic Solar Cells: Broaden the Spectrum and Optimize the Morphology.

Ternary organic solar cells (T-OSCs) have attracted significant attention as high-performance devices. In recent years, T-OSCs have achieved remarkable progress with power conversion efficiency (PCE) exceeding 19%. However, the introduction of the third component complicates the intermolecular interaction compared to the binary blend, resulting in poor controllability of active layer and limiting performance improvement. To address these issues, dual-functional third components have been developed that not only broaden the spectral range but also optimize morphology. In this review, the effect of the third component on expanding the absorption range of T-OSCs is first discussed. Second, the extra functions of the third component are introduced, including adjusting the crystallinity and molecular stack in active layer, regulating phase separation and purity, altering molecular orientation of the donor or acceptor. Finally, a summary of the current research progress is provided, followed by a discussion of future research directions.

Promoting Ruddlesden-Popper Perovskite Formation by Tailoring Spacer Intramolecular Interaction for Efficient and Stable Solar Cells.

Low-dimensional Ruddlesden-Popper phase (LDRP) perovskites are widely studied in the field of photovoltaics due to their tunable energy-band properties, enhanced photostability, and improved environmental stability compared to the 3D perovskites. However, the insulating spacers with weak intramolecular interaction used in LDRP materials limit the out-of-plane charge transport, leading to poor device performance of LDRP perovskite solar cells (PSCs). Here, a functional ligand, 3-guanidinopropanoic acid (GPA), which is capable of forming strong intramolecular hydrogen bonds through the carboxylic acid group, is employed as an organic spacer for LDRP PSCs. Owing to the strong interaction between GPA molecules, high-quality LDRP (GPA)2(MA)n-1PbnI3n+1 film with promoted formation of n = 5 phase, improved crystallinity, preferential vertical growth orientations, reduced trap-state density, and prolonged carrier lifetime is achieved using GPAI as the dimensionality regulator compared to butylamine hydroiodide (BAI). As a result, GPA-based LDRP PSC exhibits a champion power conversion efficiency of 18.16% that is much superior to the BA-based LDRP PSC (15.43%). Importantly, the optimized GPA-based LDRP PSCs without encapsulation show enhanced illumination, thermal, storage, and humidity stability compared to BA-based ones. This work provides new insights into producing high n value LDRP films and their efficient and stable PSCs.

Superior Circularly Polarized Luminescence Brightness Achieved with Chiral Heteroleptic Nine-Coordinate Coumarin-Based Tb3+ Complexes.

In order to facilitate the practical application of circularly polarized luminescence (CPL) active molecules, the CPL brightness (BCPL) must be optimized. We have applied a binary modular strategy to synthesize two chiral organo-Tb3+ complexes, [Tb(Coum)3(1R,2R-Ph-PyBox)] (2) and [Tb(Coum)3(1S,2S-Ph-PyBox)] (5), combining 3-acetyl-4-hydroxy-coumarin (Coum) and enantiopure 2,6-bis(4-phenyl-2-oxazolin-2-yl) pyridine (1R,2R/1S,2S-Ph-PyBox). The photophysical properties of these novel complexes have been fully characterized. The combined point-chiral induction capability of chiral bis(oxazoline) derivatives and the outstanding photophysical properties of the coumarin-derived ligand have resulted in an intense excited-state chiroptical activity (|glum| = 0.097-0.103) for both Tb3+ enantiomers, with a bright Tb3+-centered high-purity green emission (ΦPL = 74%) and enhanced antenna-centered absorption behavior (ε320 nm = 47820-47940 M-1 cm-1). A superior BCPL (1132.7-1205.8 M-1 cm-1 at 5D4 → 7F5) has been established for complexes 2 and 5. The strategy adopted in this work provides a new route to chiroptical organo-Tb3+ luminophores with outstanding comprehensive performance.

Studying the Thermodynamic Phase Stability of Organic-Inorganic Hybrid Perovskites Using Machine Learning.

As an important photovoltaic material, organic-inorganic hybrid perovskites have attracted much attention in the field of solar cells, but their instability is one of the main challenges limiting their commercial application. However, the search for stable perovskites among the thousands of perovskite materials still faces great challenges. In this work, the energy above the convex hull values of organic-inorganic hybrid perovskites was predicted based on four different machine learning algorithms, namely random forest regression (RFR), support vector machine regression (SVR), XGBoost regression, and LightGBM regression, to study the thermodynamic phase stability of organic-inorganic hybrid perovskites. The results show that the LightGBM algorithm has a low prediction error and can effectively capture the key features related to the thermodynamic phase stability of organic-inorganic hybrid perovskites. Meanwhile, the Shapley Additive Explanation (SHAP) method was used to analyze the prediction results based on the LightGBM algorithm. The third ionization energy of the B element is the most critical feature related to the thermodynamic phase stability, and the second key feature is the electron affinity of ions at the X site, which are significantly negatively correlated with the predicted values of energy above the convex hull (Ehull). In the screening of organic-inorganic perovskites with high stability, the third ionization energy of the B element and the electron affinity of ions at the X site is a worthy priority. The results of this study can help us to understand the correlation between the thermodynamic phase stability of organic-inorganic hybrid perovskites and the key features, which can assist with the rapid discovery of highly stable perovskite materials.

Reverse Mode Polymer Stabilized Cholesteric Liquid Crystal Flexible Films with Excellent Bending Resistance.

The reverse-mode smart windows, which usually fabricated by polymer stabilized liquid crystal (PSLC), are more practical for scenarios where high transparency is a priority for most of the time. However, the polymer stabilized cholesteric liquid crystal (PSCLC) film exhibits poor spacing stability due to the mobility of CLC molecules during the bending deformation. In this work, a reverse-mode PSCLC flexible film with excellent bending resistance was fabricated by the construction of polymer spacer columns. The effect of the concentration of the polymerizable monomer C6M and chiral dopant R811 on the electro-optical properties and polymer microstructure of the film were studied. The sample B2 containing 3 wt% of C6M and 3 wt% R811 presented the best electro-optical performance. The electrical switch between transparent and opaque state of the flexible PSCLC film after bending not only indicated the excellent electro-optical switching performance, but also demonstrated the outstanding bending resistance of the sample with polymer spacer columns, which makes the PSCLC film containing polymer spacer columns have a great potential to be applied in the field of flexible devices.

A Nickel/Organoboron-Catalyzed Coupling of Aryl Bromides with Sodium Sulfinates: The Synthesis of Sulfones under Visible Light.

An efficient cross-coupling of aryl bromides with sodium sulfinates, using an organoboron photocatalyst with nickel, is described herein. Under the irradiation of white light, this dually catalytic system enables the synthesis of a series of sulfone compounds in moderate to good yields. A broad range of functional groups and heteroaromatic compounds is tolerated under these reaction conditions. The use of an organoboron photocatalyst highlights a sustainable alternative to iridium or ruthenium complexes. These findings contribute to the field of photochemistry and provide a greener approach to sulfone synthesis.

Polymer-Dispersed Liquid Crystal Films on Flexible Substrates with Excellent Bending Resistance and Spacing Stability.

Polymer-dispersed liquid crystals (PDLCs) are very attractive due to their electrically switchable properties. However, current PDLC films still have problems such as high driving voltages, low contrast ratio (CR), and poor bending resistance and spacing stability. To solve these problems, a PDLC film with a system of coexisting polymer spacer columns and polymer network was proposed. First, based on the adhesive systems of IBMA and UV6301, the effects of IBMA concentration and LC content on the morphology of the polymer network and the electro-optical properties of PDLC were investigated, respectively. Then, the effects of the process conditions of mask polymerization such as temperature, time, and UV light intensity on the morphology and electro-optical properties of the polymer spacer columns were systematically investigated. It was found that PDLC films with the coexistence system exhibit both excellent electro-optical properties and outstanding bending resistance and spacing stability. Thus, it provides new practical possibilities for the preparation of high-performance PDLC films used in flexible devices.

A bistable cholesteric liquid crystal film stabilized by a liquid-crystalline epoxy/thiol compound-based polymer.

Bistable cholesteric liquid crystals have promising application prospects in various fields, such as smart windows and displays. However, the long-term stability of two individual states is not easy to achieve, hindering their practical use. In this research, the bistable feature was enhanced by constructing a microsphere-type polymer with a liquid-crystalline epoxy/thiol monomer in negative dielectric anisotropic cholesteric liquid crystals. Spectroscopic and optical examinations revealed that either the transparent planar state or the opaque focal conic state can be maintained without the aid of an external field. Moreover, they can be switched to each other by applying a high- or low-frequency electric field. Further, factors such as the chemical structure of thiol compounds, curing temperature and curing time were investigated to explore their influences on the micro morphology of the polymer and thereby the electro-optical properties. In addition, the frequency-dependent driving scheme was analysed. Finally, bistable switching was demonstrated using an optimized sample. This energy-efficient bistable film shines light on future applications in smart windows, photonic paper and other electro-optical devices.

Research Progress on Intrinsically Conductive Polymers and Conductive Polymer-Based Composites for Electromagnetic Shielding.

Electromagnetic shielding materials are special materials that can effectively absorb and shield electromagnetic waves and protect electronic devices and electronic circuits from interference and damage by electromagnetic radiation. This paper presents the research progress of intrinsically conductive polymer materials and conductive polymer-based composites for electromagnetic shielding as well as an introduction to lightweight polymer composites with multicomponent systems. These materials have excellent electromagnetic interference shielding properties and have the advantages of electromagnetic wave absorption and higher electromagnetic shielding effectiveness compared with conventional electromagnetic shielding materials, but these materials still have their own shortcomings. Finally, the paper also discusses the future opportunities and challenges of intrinsically conductive polymers and composites containing a conductive polymer matrix for electromagnetic shielding applications.

CeO2-Supported TiO2-Pt Nanorod Composites as Efficient Catalysts for CO Oxidation.

Supported Pt-based catalysts have been identified as highly selective catalysts for CO oxidation, but their potential for applications has been hampered by the high cost and scarcity of Pt metals as well as aggregation problems at relatively high temperatures. In this work, nanorod structured (TiO2-Pt)/CeO2 catalysts with the addition of 0.3 at% Pt and different atomic ratios of Ti were prepared through a combined dealloying and calcination method. XRD, XPS, SEM, TEM, and STEM measurements were used to confirm the phase composition, surface morphology, and structure of synthesized samples. After calcination treatment, Pt nanoparticles were semi-inlayed on the surface of the CeO2 nanorod, and TiO2 was highly dispersed into the catalyst system, resulting in the formation of (TiO2-Pt)/CeO2 with high specific surface area and large pore volume. The unique structure can provide more reaction path and active sites for catalytic CO oxidation, thus contributing to the generation of catalysts with high catalytic activity. The outstanding catalytic performance is ascribed to the stable structure and proper TiO2 doping as well as the combined effect of Pt, TiO2, and CeO2. The research results are of importance for further development of high catalytic performance nanoporous catalytic materials.

Effect of Electrospinning Network Instead of Polymer Network on the Properties of PDLCs.

In this study, polymer-dispersed liquid crystal (PDLC) membranes were prepared by combining prepolymer, liquid crystal, and nanofiber mesh membranes under UV irradiation. EM, POM, and electro-optic curves were then used to examine the modified polymer network structure and the electro-optical properties of these samples. As a result, the PDLCs with a specific amount of reticular nanofiber films had considerably improved electro-optical characteristics and antiaging capabilities. The advancement of PDLC incorporated with reticulated nanofiber films, which exhibited a faster response time and superior electro-optical properties, would greatly enhance the technological application prospects of PDLC-based smart windows, displays, power storage, and flexible gadgets.

Preparation of transmittance-switchable composites from a coexistent system of polymer-dispersed and polymer-stabilized cholesteric liquid crystals.

Polymer-dispersed and polymer-stabilized liquid crystals (PD&PSLCs) are the coexistent systems of PDLCs and PSLCs, in which a mesogenic polymer network forms in the LC droplets to construct the PSLC system and the combination of the LC domains and the isotropic polymer matrix makes up the PDLC system. In this work, a PD&PS cholesteric LC (PD&PSCLC) system, where the isotropic polymer walls make up the PDCLC microstructure and the liquid crystalline polymer network in the CLC droplets constructs the PSCLC system, is fabricated successfully. The CLCs are composed of a negative dielectric anisotropy nematic LC and a chiral dopant. Owing to the stabilizing effect of the liquid crystalline polymer network, the planar texture of the CLCs can be retained after the preparation process, and the PD&PSCLC sample is in a large-transmittance state. The action of a low-frequency electric field induces the disordered texture of the CLCs and the light-scattering (low-transmittance) state because of the electro-hydrodynamic effect and dynamic scattering effects. After the removal of the low-frequency electric field, the stabilizing effect of the liquid crystalline polymer network induces the CLC molecules to return to the homogeneous orientation state, and the sample also re-obtains the large transmittance. This work may provide a facile approach to fabricating polymer/CLC composites with switchable transmittance for reverse-mode smart windows.

An Electrically and Thermally Erasable Liquid Crystal Film Containing NIR Absorbent Carbon Nanotube.

Carbon nanotubes (CNTs) coated by a poly(vinylpyrrolidone) (PVP) layer were doped in bistable cholesteric liquid crystal (ChLC) film to provide electric, thermal, or optical erasability controllable films. The CNT/PVP formed a compatible NIR-absorbing film that can generate heat to switch ChLC film from a planar texture to a focal conic texture. The appropriate content of CNT/PVP is provided to achieve a fast thermal response, satisfactory dispersion, and clear display brightness. The ChLC film containing CNT/PVP @ 0.8 (wt.%) saves 51% time at thermal erasing, compared to the ChLC mixture without NIR absorbent. The hybrid organic-inorganic bistable ChLC material reported here extends and offers new applications of ChLC writing tablets.

Photoacoustic Effect of Near-Infrared Absorbing Organic Molecules via Click Chemistry.

Near-infrared dyes were developed to be contrast agents due to their ability to improve the productivity of photoacoustic (PA) imaging and photothermal therapy (PTT) treatments. During the article, we described in detail the PA and PT effects of a category of organic molecules. F4-TCNQ could potentially cause a red-shift in the peak PA intensity. The results show that the PTT intensity of the near-infrared dyes with phenyl groups were higher than near-infrared dyes with thiophene groups. We also investigated the photodynamic treatment effect of C1b to demonstrate that these dyes are highly desirable in biochemistry. The high photoacoustic intensity of the organic molecules and the good yield of reactive oxygen species could indicate that these dyes have good potential for a wide range of imaging applications. Finally, we embedded the dye (C1b) in a liposomal hydrophobic phospholipid bilayer (C1b⊂L) to facilitate the application of hydrophobic dyes in biomedical applications, which can be absorbed by cells with good compatible and high stability for the imaging of cellular PA.

Silicon nanostructure-doped polymer/nematic liquid crystal composites for low voltage-driven smart windows.

In this work, two silicon nanostructures were doped into polymer/nematic liquid crystal composites to regulate the electric-optical performance. Commercial SiO2nanoparticles and synthesized thiol polyhedral oligomeric silsesquioxane (POSS-SH) were chosen as the dopants to afford the silicon nanostructures. SiO2nanoparticles were physically dispersed in the composites and the nanostructure from POSS-SH was implanted into the polymer matrix of the composites via photoinduced thiol-ene crosslinking. Scanning electron microscopy results indicated that the implantation of POSS microstructure into the polymer matrix was conducive to obtaining the uniform porous polymer microstructures in the composites while the introduction of SiO2nanoparticles led to the loose and heterogeneous polymer morphologies. The electric-optical performance test results also demonstrated that the electric-optical performance regulation effect of POSS microstructure was more obvious than that of SiO2nanoparticles. The driving voltage was reduced by almost 80% if the concentration of POSS-SH in the composite was nearly 8 wt% and the sample could be completely driven by the electric field whose voltage was lower than the safe voltage for continuous contact (24 V). This work could provide a creative approach for the regulation of electric-optical performance for polymer/nematic liquid crystal composites and the fabrication of low voltage-driven PDLC films for smart windows.

Unsymmetrical Diboron Reagents: Application in Borylation Reactions of Unsaturated Bonds.

In the past decades, borylation reactions have received extensive research interest and have developed into effective tools in the synthesis of versatile organoboron compounds. Boranes and symmetrical diboron compounds are commonly utilized as borylating reagents in these transformations, especially in the borylation reactions of unsaturated bonds. More recently, several types of unsymmetrical diboron reagents have been synthesized and applied in these borylation reactions, allowing for complementary chemo- and regioselectivity. This review aimed to highlight the recent development in this rising research field, focusing on new reactivity and selectivity that originates from the use of these unsymmetrical diboron reagents.

Correction: Ding, S., et al. NNB-Type Tridentate Boryl Ligands Enabling a Highly Active Iridium Catalyst for C⁻H Borylation. Molecules 2019, 24, 1434.

The authors wish to make the following corrections to this paper [...].

NNB-Type Tridentate Boryl Ligands Enabling a Highly Active Iridium Catalyst for C⁻H Borylation.

Boryl ligands play a very important role in catalysis because of their very high electron-donating property. In this paper, NNB-type boryl anions were designed as tridentate ligands to promote aryl C-H borylation. In combination with [IrCl(COD)]2, they generate a highly active catalyst for a broad range of (hetero)arene substrates, including highly electron-rich and/or sterically hindered ones. This work provides a new NNB-type tridentate boryl ligand to support homogeneous organometallic catalysis.

Direct Transformation from Arylamines to Aryl Naphthalene-1,8-diamino Boronamides: A Metal-Free Sandmeyer-Type Process.

A direct metal-free transformation from arylamines to aryl naphthalene-1,8-diamino boronamides, a type of masked boronic acid, has been developed based on Sandmeyer-type reactions. A nonsymmetrical diboron reagent, B(pin)-B(dan), was utilized as the borylating reagent, and the B(dan) moiety was transferred to the aim products selectively. This conversion tolerated a series of functional groups, including chloro, bromo, fluoro, ester, hydroxy, cyano and amide.

Nanocomposite Materials for the Sodium-Ion Battery: A Review.

Clean energy has become an important topic in recent decades because of the serious global issues related to the development of energy, such as environmental contamination, and the intermittence of the traditional energy sources. Creating new battery-related energy storage facilities is an urgent subject for human beings to address and for solutions for the future. Compared with lithium-based batteries, sodium-ion batteries have become the new focal point in the competition for clean energy solutions and have more potential for commercialization due to the huge natural abundance of sodium. Nevertheless, sodium-ion batteries still exhibit some challenges, like inferior electrochemical performance caused by the bigger ionic size of Na+ ions, the detrimental volume expansion, and the low conductivity of the active materials. To solve these issues, nanocomposites have recently been applied as a new class of electrodes to enhance the electrochemical performance in sodium batteries based on advantages that include the size effect, high stability, and excellent conductivity. In this Review, the recent development of nanocomposite materials applied in sodium-ion batteries is summarized, and the existing challenges and the potential solutions are presented.