B-Site Co-Doping Coupled with Additive Passivation Pushes the Efficiency of Pb-Sn Mixed Inorganic Perovskite Solar Cells to Over 17.

Pb-Sn mixed inorganic perovskite solar cells (PSCs) have garnered increasing interest as a viable solution to mitigate the thermal instability and lead toxicity of hybrid lead-based PSCs. However, the relatively poor structural stability and low device efficiency hinder its further development. Herein, high-performance manganese (Mn)-doped Pb-Sn-Mn-based inorganic perovskite solar cells (PSCs) are successfully developed by introducing Benzhydroxamic Acid (BHA) as multifunctional additive. The incorporation of smaller divalent Mn cations contributes to a contraction of the perovskite crystal, leading to an improvement in structural stability. The BHA additive containing a reductive hydroxamic acid group (O═C-NHOH) not only mitigates the notorious oxidation of Sn2+ but also interacts with metal ions at the B-site and passivates related defects. This results in films with high crystallinity and low defect density. Moreover, the BHA molecules tend to introduce a near-vertical dipole moment that parallels the built-in electric field, thus facilitating charge carrier extraction. Consequently, the resulting device delivers a champion PCE as high as 17.12%, which represents the highest reported efficiency for Pb-Sn-based inorganic PSCs thus far. Furthermore, the BHA molecule provides an in situ encapsulation of the perovskite grain boundary, resulting in significant enhancement of device air stability.

Pressure-induced polymerization and bandgap-adjustment of TPEPA.

Organic solar cells have become an important development direction in solar cell materials because of their low cost, light weight, and good flexibility. However, the size of their bandgap is difficult to continuously regulate, resulting in a low power conversion efficiency. In this work, an organic molecule TPEPA was synthesized, and its luminescence performance and polymerization under high pressure were studied by performing in situ Raman, IR, fluorescence, and UV-vis spectroscopy. The Raman and IR spectroscopic results show that single bonds (C-H, C-Ph) and long chains (C-C[triple bond, length as m-dash]C-C) are more unstable and prone to amorphization under high pressure. At 10 GPa, the TPEPA molecule undergoes a transition of amorphization accompanied by a few polymerizations in the C[triple bond, length as m-dash]C bond structure. After holding pressure at 20 GPa for one day and releasing to ambient pressure, the other peaks almost disappeared, while the new peak of C(sp3)-H from the polymerization of the benzene ring was observed, indicating that the irreversible amorphization and polymerization did occur. UV-vis spectra results show that the bandgap is reduced from 2.9 eV to 1.3 eV, which is just in the maximum conversion efficiency bandgap range (1.3-1.4 eV) of p-n junction solar cell materials. This pressure is within the working pressure range of a large volume press, which is favorable in applications of large-scale synthesis. Our strategy may provide a method for the large-scale synthesis of novel organic solar cell materials.

Oxalate Pushes Efficiency of CsPb0.7 Sn0.3 IBr2 Based All-Inorganic Perovskite Solar Cells to over 14.

All-inorganic CsPbIBr2 perovskite solar cells (PSCs) have recently gained growing attention as a promising template to solve the thermal instability of organic-inorganic PSCs. However, the relatively low device efficiency hinders its further development. Herein, highly efficient and stable CsPb0.7 Sn0.3 IBr2 compositional perovskite-based inorganic PSCs are fabricated by introducing appropriate amount of multifunctional zinc oxalate (ZnOX). In addition to offset Pb and Sn vacancies through Zn2+ ions incorporation, the oxalate group can strongly interact with undercoordinated metal ions to regulate film crystallization, delivering perovskite film with low defect density, high crystallinity, and superior electronic properties. Correspondingly, the resulting device delivers a champion efficiency of 14.1%, which presents the highest reported efficiency for bromine-rich inorganic PSCs thus far. More importantly, chemically reducing oxalate group can effectively suppress the notorious oxidation of Sn2+ , leading to significant enhancement on air stability.

C60(OH)12 and Its Nanocomposite for High-Performance Lithium Storage.

Organic carbon materials, such as graphene and nanotubes, with a high specific capacity show promise in improving the energy density for lithium ion batteries (LiBs). Here, we report on the synthesis and characterization of C60(OH)12 and the C60(OH)12/graphene oxide (GO) composite and demonstrate their use as anode materials in LiBs. We find that the C60(OH)12/GO composite forms due to the chemical reactions between the carboxyl and epoxy groups of GO and the hydroxyl of C60(OH)12 nanoparticles and that C60(OH)12 uniformly grows on the surface of GO nanosheets. Using a suite of spectroscopy probes, we unequivocally show the mixing between C60(OH)12 and GO at the molecular level, which leads to superior battery performances. This composite has a reversible capacity of 1596 mAh g-1 at 0.2 A g-1, higher than the capacities of C60(OH)12 and GO. This composite has a superior cycling stability and excellent rate performance, making it a promising organic anode material for high-performance LiBs.

Biomimetic Synchronized Motion of Two Interacting Macrocycles in [3]Rotaxane-Based Molecular Shuttles.

Noncovalent interactions between all the neighboring components in biomolecular machines are responsible for their synchronized motion and thus complex functions. This strategy has rarely been used in multicomponent molecular machines. Here, we report four [3]rotaxane-based molecular shuttles. Noncovalent interactions among the three components (two interacting macrocycles and one axle) not only cause a "systems-level" effect on the relative positions of the two macrocycles along the axle, but also result in a synchronized motion of the two macrocycles when adding partial amount of stimuli. Moreover, the intermediate state with one shuttled macrocycle even exist predominantly in the solution during the titration of stimuli, which is theoretically unexpected for the [3]rotaxane with two non-interacting rings. This biomimetic strategy may provide a method for constructing highly complex molecular machines.

Multiphotoluminescence from a Triphenylamine Derivative and Its Application in White Organic Light-Emitting Diodes Based on a Single Emissive Layer.

White organic light-emitting diode (WOLED) technology has attracted considerable attention because of its potential use as a next-generation solid-state lighting source. However, most of the reported WOLEDs that employ the combination of multi-emissive materials to generate white emission may suffer from color instability, high material cost, and a complex fabrication procedure which can be diminished by the single-emitter-based WOLED. Herein, a color-tunable material, tris(4-(phenylethynyl)phenyl)amine (TPEPA), is reported, whose photoluminescence (PL) spectrum is altered by adjusting the thermal annealing temperature nearly encompassing the entire visible spectra. Density functional theory calculations and transmission electron microscopy results offer mechanistic understanding of the PL redshift resulting from thermally activated rotation of benzene rings and rotation of 4-(phenylethynyl) phenyl)amine connected to the central nitrogen atom that lead to formation of ordered molecular packing which improves the π-π stacking degree and increases electronic coupling. Further, by precisely controlling the annealing time and temperature, a white-light OLED is fabricated with the maximum external quantum efficiency of 3.4% with TPEPA as the only emissive molecule. As far as it is known, thus far, this is the best performance achieved for single small organic molecule based WOLED devices.

Directional Shuttling of a Stimuli-Responsive Cone-Like Macrocycle on a Single-State Symmetric Dumbbell Axle.

Rotaxane-based molecular shuttles are often operated using low-symmetry axles and changing the states of the binding stations. A molecular shuttle capable of directional shuttling of an acid-responsive cone-like macrocycle on a single-state symmetric dumbbell axle is now presented. The axle contains three binding stations: one symmetric di(quaternary ammonium) station and two nonsymmetric phenyl triazole stations arranged in opposite orientations. Upon addition of an acid, the protonated macrocycle shuttles from the di(quaternary ammonium) station to the phenyl triazole binding station closer to its butyl groups. This directional shuttling presumably originates from charge repulsion and an orientational binding preference between the cone-like cavity and the nonsymmetric phenyl triazole station. This mechanism for achieving directional shuttling by manipulating only the wheels instead of the tracks is new for artificial molecular machines.

Light-Controlled Switching of a Non-photoresponsive Molecular Shuttle.

In this research, we report that the acid/base-switchable molecular shuttle without any photoresponsive group can be controlled photochemically by coupling to the indazole-based photoacid via an intermolecular proton-transfer process. The photocontrolled shuttling of the wheel can be conveniently monitored by following the fluorescent evolution during the photoirradiation.

In situ production of silver nanoparticles on an aldehyde-equipped conjugated porous polymer and subsequent heterogeneous reduction of aromatic nitro groups at room temperature.

In a metal-free procedure, chelating thiol groups and an electrophile react to assemble a robust, conjugated porous polymer with pendant aldehyde functionalities. These groups are able to reduce Ag(i) ions to generate, in situ, Ag(0) nanoparticles evenly dispersed in the polymer matrix. The Ag(0)-polymer composite enables selective reduction of aromatic nitro compounds as a heterogeneous catalyst, and can be conveniently recycled multiple times.

Pd uptake and H2S sensing by an amphoteric metal-organic framework with a soft core and rigid side arms.

Molecular components of opposite character are often incorporated within a single system, with a rigid core and flexible side arms being a common design choice. Herein, molecule L has been designed and prepared featuring the reverse design, with rigid side arms (arylalkynyl) serving to calibrate the mobility of the flexible polyether links in the core. Crystallization of this molecule with Pb(II)  ions led to a dynamic metal-organic framework (MOF) system that not only exhibits dramatic, reversible single-crystal-to-single-crystal transformations, but combines distinct donor and acceptor characteristics, allowing for substantial uptake of PdCl2 and colorimetric sensing of H2 S in water.

An electroactive porous network from covalent metal-dithiolene links.

Simple synthesis and versatile functions: by directly reacting a triphenylene hexathiol molecule (HTT) with PtCl2, a covalent metal-organic framework (CMOF) has been prepared that features substantial porosity, redox activity and ion exchange capability.

Convenient detection of Pd(II) by a metal-organic framework with sulfur and olefin functions.

A highly specific, distinct color change in the crystals of a metal-organic framework with pendant allyl thioether units in response to Pd species was discovered. The color change (from light yellow to orange/brick red) can be triggered by Pd species at concentrations of a few parts per million and points to the potential use of these crystals in colorimetric detection and quantification of Pd(II) ions. The swift color change is likely due to the combined effects of the multiple functions built into the porous framework: the carboxyl groups for bonding with Zn(II) ions to assemble the host network and the thioether and alkene functions for effective uptake of the Pd(II) analytes (e.g., via the alkene-Pd interaction). The resultant loading of Pd (and other noble metal) species into the porous solid also offers rich potential for catalysis applications, and the alkene side chains are amenable to wide-ranging chemical transformations (e.g., bromination and polymerization), enabling further functionalization of the porous networks.

Synthesis and DNA-binding affinities of protoberberine-based multivalent agents.

Three novel berberine derivatives bearing two, three, and four primary amino groups at C(9), respectively, were synthesized and characterized on the basis of ¹H- and ¹³C-NMR, MS, and HR-MS data. Their non-covalent binding with calf thymus (CT) DNA was investigated by means of spectrophotometric titration and ethidium bromide (EB) displacement experiments. The results indicated that these multivalent berberine derivatives exhibited up to 130-fold enhanced binding affinities relative to berberine, and thus, may be exploitable as potent DNA-binding agents.

Design, synthesis, and biological evaluation of novel water-soluble triptolide derivatives: Antineoplastic activity against imatinib-resistant CML cells bearing T315I mutant Bcr-Abl.

Imatinib (STI571) is the frontline targeted-therapeutic agent for patients with chronic myelogenous leukemia (CML). However, resistance to imatinib due to point mutations in Bcr-Abl kinase domain is an emerging problem. We recently reported that triptolide (compound 1) could effectively kill CML cells including those harboring T315I mutant Bcr-Abl. In the present study, we designed a series of C-14 triptolide derivatives with C-14-hydroxyl substituted by different amine esters (3-18): 3-6 and 13 (by aliphatic chain amine esters); 7-9, 11, 12 and 15-18 (by alicyclic amine esters with different size), and 10 and 14 (by aralkylamine esters).The compounds were examined for their antineoplastic activity against CML cells (including KBM5-T315I cells) in terms of proliferation inhibition, apoptosis and signal transduction. Nude mouse xenograft model was also used to evaluate the in vivo activity. Compounds 2-9, 11-14, 17 and 18 exhibited a potent inhibitory activity against KBM5 and KBM5-T315I cells. This series of derivatives down-regulated Bcr-Abl mRNA. Compounds 4, 5, 8 and 9 were further examined for their impact on signaling and apoptosis with immunoblotting. Compound 5 was chosen for evaluation in a nude mouse xenograft model. The stereo-hindrance of C-14 group appeared to be responsible for the antitumor effect. The computational small molecule-protein docking analysis illustrated the possible interaction between compound 9 and RNA polymerase II. Our results suggest that this series of derivatives may be promising agents to overcome imatinib-resistance caused by the Bcr-Abl-T315I mutation.