The all-inorganic α-CsPbI3 perovskite with the most suitable band gap faces serious challenges of low phase stability and high moisture sensitivity. We discover that a simple phenyltrimethylammonium bromide (PTABr) post-treatment could achieve a bifunctional stabilization including both gradient Br doping (or alloying) and surface passivation. The PTABr treatment on CsPbI3 only induces less than 5 nm blue shift in UV–vis absorbance but significantly stabilize the perovskite phase with much better stability. Finally, the highly stable PTABr treated CsPbI3 based perovskite solar cells exhibit a reproducible photovoltaic performance with a champion efficiency up to 17.06% and stable output of 16.3%. Therefore, this one-step bifunctional stabilization of perovskite through gradient halide doping and surface organic cation passivation presents a novel and promising strategy to design stable and high performance all-inorganic lead halide.
Understanding the mechanism of nanoparticle self-assembly is of critical significance for developing synthetic strategies for complex nanostructures. By encapsulating aggregates of Au nanospheres in shells of polystyrene-block-poly(acrylic acid), we prevent the dissociation and aggregation typically associated with the drying of solution samples on TEM/SEM substrates. In our study of the salt-induced aggregation of 2-naphthalenethiol-functionalized Au nanospheres in DMF, the trapping of the solution species under various experimental conditions permits new insights in the mechanism thereof. We provide evidence that the spontaneous linear aggregation in this system is a kinetically controlled process and hence the long-range charge repulsion at the "transition state" before the actual contact of the Au nanospheres is the key factor. Thus, the charge repulsion potential (i.e. the activation energy) a nanosphere must overcome before attaching to either end of a nanochain is smaller than attaching on its sides, which has been previously established. This factor alone could give rise to the selective end-on attachment and lead to the linear assembly of originally isotropic Au nanospheres.
A central theme in nanotechnology is to advance the fundamental understanding of nanoscale component assembly, thereby allowing rational structural design that may lead to materials with novel properties and functions. nanoparticles (nPs) are often regarded as 'artificial atoms', but their 'reactions' are not readily controllable. Here, we demonstrate a complete nanoreaction system whereby colloidal nPs are rationally assembled and purified. Two types of functionalized gold nPs (A and B) are bonded to give specific products AB, AB 2 , AB 3 and AB 4 . The stoichiometry control is realized by fine-tuning the charge repulsion among the B-nPs. The products are protected by a polymer, which allows their isolation in high purity. The integration of hetero-assembly, stoichiometry control, protection scheme and separation method may provide a scalable way to fabricate sophisticated nanostructures.
All-inorganic lead halide perovskites α-CsPbI 2 Br with higher thermal stability and phase stability are promising candidate for optoelectronic application such as photovoltaics. However, the >250 C high temperature annealing is required to obtain the desired photovoltaic active perovskite phase of α-CsPbI 2 Br, which makes it difficult for fabrication and application based on flexible polymer substrate. Here, a facile formation of high performance allinorganic CsPbI 2 Br perovskite solar cell is reported, through a one-step method and a 100-130 C low temperature annealing process. The faciledeposited CsPbI 2 Br film demonstrates long-term phase stability at room temperature for a month and exhibits the thermal stability under 100 C annealing for more than a week. Consequently, the CsPbI 2 Br-based allinorganic perovskite solar cells (PSCs) exhibit power conversion efficiencies (PCE) of up to a record value of 10.56%. This low temperature crystallization of all-inorganic CsPbI 2 Br perovskite is a promising approach for scalable, convenient, and inexpensive fabrication in the future.Organic-inorganic hybrid lead halide perovskites have emerged as one class of most promising optoelectronic materials for various application due to their excellent optical absorption, good carrier mobility, and lifetime. [1][2][3][4] The power conversion efficiency (PCE) of organic-inorganic hybrid halide perovskite solar cells has progressed rapidly from unstable 3.8% to a certified 22.1% and their stability has also been significantly improved in a relatively short span of time, which make them promising for commercialization. [5][6][7][8] With the progress of these organic-inorganic hybrid perovskite, all-inorganic halide perovskite has demonstrated to be another promising novel alternative candidate for various optoelectronic applications. [9][10][11][12][13][14][15] These allinorganic lead halide perovskites of CsPbX 3 (X ¼ I, Br, Cl) have advantage of higher thermal stability over the well-studied organic-inorganic hybrid lead halide perovskites, such as MAPbX 3 (X ¼ I, Br, Cl). [16][17][18] The excellent thermal stability of all-inorganic lead halide perovskites can be ascribed to the absence of volatile organic component and the higher formation energy. [19] The high formation or crystallization energy helps enhance the thermal stability of CsPbX 3 perovskite but also induces the difficulty for fabrication. Now, CsPbX 3 -based perovskite can be either fabricated via a generally solution-process similar to the hybrid lead halide perovskites or advanced vacuum deposition. [20] Regarding on the solution-process, most reported CsPbX 3 exhibits a yellow orthorhombic phase upon formation at low temperature, which is unsuitable for solar cell applications. [21,22] Followed by a second-high temperature annealing, these yellow phases can form a black cubic perovskite phase. Generally, the yellow-to-black phase transformation occurs at temperatures of above 300 C. [23][24][25][26] A recent investigation on the crystal behavior of CsPb...
Here, we demonstrate that a single biochemical assay is able to predict the tissue-selective pharmacology of an array of selective estrogen receptor modulators (SERMs). We describe an approach to classify estrogen receptor (ER) modulators based on dynamics of the receptor-ligand complex as probed with hydrogen/deuterium exchange (HDX) mass spectrometry. Differential HDX mapping coupled with cluster and discriminate analysis effectively predicted tissue-selective function in most, but not all, cases tested. We demonstrate that analysis of dynamics of the receptor-ligand complex facilitates binning of ER modulators into distinct groups based on structural dynamics. Importantly, we were able to differentiate small structural changes within ER ligands of the same chemotype. In addition, HDX revealed differentially stabilized regions within the ligand-binding pocket that may contribute to the different pharmacology phenotypes of the compounds independent of helix 12 positioning. In summary, HDX provides a sensitive and rapid approach to classify modulators of the estrogen receptor that correlates with their pharmacological profile. discriminate analysis ͉ hydrogen/deuterium exchange ͉ mass spectrometry T he estrogen receptors (ER␣ and ER) are important transcriptional regulators that mediate a number of fundamental processes including regulation of the reproductive system and the maintenance of skeletal and cardiovascular tone. As such, these receptors are the molecular targets of drugs used to treat diseases such as breast cancer and osteoporosis. Both beneficial and detrimental effects of ER ligands have been demonstrated in target tissues, thus tissue-selective ER ligands have been developed and are termed selective estrogen receptor modulators (SERMs). Traditional drug discovery programs for ER modulators most often involve the use of a receptor-binding assay as a primary screen to identify high-affinity ligands, followed by the use of in vitro cellbased assays to determine the functional activity of a given ligand (1). Compounds with the desired intrinsic properties for affinity and selective functional response are then evaluated for in vivo efficacy in animal models of the targeted disease. Although this drugdiscovery paradigm has been used successfully to identify most of the clinically-relevant SERMs discovered to date, the ability of in vitro biochemical and cell-based functional assays to translate to in vivo tissue selectivity has been limited. Cofactor recruitment assays have proven to be a useful tool to detect ligand-induced conformational changes for many nuclear receptors but can be less effective for profiling SERMs because the key coactivator interaction surface (AF-2) has been blocked by the ligand-induced repositioning of helix 12.Classical approaches for structural analysis of receptor-ligand interaction involve the use of x-ray crystallography or NMR spectroscopy. The importance of studying changes to protein dynamics during ER modulation has been demonstrated by Tamrazi et al. (2). In a serie...
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