Large-Scale Ligand-Free Synthesis of Homogeneous Core-Shell Quantum-Dot-Modified CsPbBr Microcrystals.

An organic ligand-free solution method is developed for preparing homogeneous core-shell quantum-dot (QD)-modified pure CsPbBr microcrystals on a large scale (∼12 g) at room temperature. The ligand-free CsPbBr microcrystals show a high green photoluminescence quantum yield of 76% with 360 nm of excitation light, which is attributed to their unique microarchitecture, with several features including quantum confinement of the outer QDs, stability of the inner CsPbBr microcrystals, improved light trapping, and interfacial recombination. UV-vis-near-IR and photoluminescence analyses provide valued evidence to support the ligand-free CsPbBr with synergy between the QDs and microcrystals.

Effect of layer and stacking sequence in simultaneously grown 2H and 3R WS atomic layers.

In two-dimensional layered materials, layer number and stacking order have strong effects on the optical and electronic properties. Tungsten disulfide (WS) crystal, as one important member among transition metal dichalcogenides, has been usually prepared in a layered 2H prototype structure with space group P6/mmc ([Formula: see text]) in spite of many other expected ones such as 3R. Here, we report simultaneous growth of 2H and 3R stacked multilayer (ML) WS crystals in large scale by chemical vapor deposition and effects of layer number and stacking order on optical and electronic properties.

Microconcave MAPbBr Single Crystal for High-Performance Photodetector.

We present the first report of a new suspension method for obtaining cubic MAPbBr single crystal with a concave surface. The cubic MAPbBr crystal with microconcavity possesses good crystallinity and carrier lifetime. Excellent photoelectric performance was provided by the concavity-based MAPbBr photodetectors because of the good light trapping and shortened carrier pathway.

Low-Temperature In Situ Amino Functionalization of TiO Nanoparticles Sharpens Electron Management Achieving over 21% Efficient Planar Perovskite Solar Cells.

Titanium oxide (TiO ) has been commonly used as an electron transport layer (ETL) of regular-structure perovskite solar cells (PSCs), and so far the reported PSC devices with power conversion efficiencies (PCEs) over 21% are mostly based on mesoporous structures containing an indispensable mesoporous TiO layer. However, a high temperature annealing (over 450 °C) treatment is mandatory, which is incompatible with low-cost fabrication and flexible devices. Herein, a facile one-step, low-temperature, nonhydrolytic approach to in situ synthesizing amino-functionalized TiO nanoparticles (abbreviated as NH -TiO NPs) is developed by chemical bonding of amino (-NH ) groups, via TiN bonds, onto the surface of TiO NPs.

Anchoring Fullerene onto Perovskite Film via Grafting Pyridine toward Enhanced Electron Transport in High-Efficiency Solar Cells.

Fullerene derivatives have been popularly applied as electron transport layers (ETLs) of inverted (p-i-n) planar heterojunction perovskite solar cells (iPSCs) due to their strong electron-accepting abilities, and so far, [6,6]-phenyl-C-butyric acid methyl ester (PCBM) has been the most commonly used ETL, which suffers, however, from high cost due to the complicated synthetic route. Herein, novel pyridine-functionalized fullerene derivatives (abbreviated as C-Py) were synthesized facilely via a one-step 1,3-dipolar cycloaddition reaction and applied as ETLs superior to PCBM in iPSC devices. Three pyridine-functionalized fullerene derivatives with different alkyl groups, including methyl, n-butyl, and n-hexyl, grafted onto the pyrrolidine moiety (abbreviated as C-MPy, C-BPy, and C-HPy, respectively) were synthesized.

Phase Engineering of Perovskite Materials for High-Efficiency Solar Cells: Rapid Conversion of CHNHPbI to Phase-Pure CHNHPbCl via Hydrochloric Acid Vapor Annealing Post-Treatment.

Organometal halide CHNHPbI (MAPbI) has been commonly used as the light absorber layer of perovskite solar cells (PSCs), and, especially, another halide element chlorine (Cl) has been often incorporated to assist the crystallization of perovskite film. However, in most cases, a predominant MAPbI phase with trace of Cl is obtained ultimately and the role of Cl involvement remains unclear. Herein, we develop a low-cost and facile method, named hydrochloric acid vapor annealing (HAVA) post-treatment, and realize a rapid conversion of MAPbI to phase-pure MAPbCl, demonstrating a new concept of phase engineering of perovskite materials toward efficiency enhancement of PSCs for the first time.