Search

Summary Although great progress is being made toward improving the power conversion efficiency (PCE) and the operational stability of perovskite solar cells (PSCs), little attention is being paid to their mechanical reliability, which is particularly important for flexible PSCs (f-PCSs). Here, we have grown low-dimensional (LD) metal-halide perovskite (MHP) thin capping layer over the 3D MHP light-absorber thin film in f-PSCs in situ to improve their mechanical reliability. This resulted in f-PSCs with unprecedented, simultaneous improvements in PCE (21.0%), operational stability (T90, retention of 90% of the initial PCE, >800 h), and bending durability (T80 = 20,000 tension-only bending cycles). These synergistic virtuous effects are attributed to the LD MHP capping layer enhancing photocarriers extraction, providing protection against the environment, and “sealing” surface flaws on the 3D MHP thin film. The latter reduces the propensity for cracking in bending, which results in improved environmental stability and bending durability.

Understanding the photoinduced carrier dynamics in Cs2AgBiBr6 double perovskites is essential for their application in optoelectronic devices. Herein, we report an investigation on the temperature-...

Currently, three-dimensional (3D) organic–inorganic hybrid metallic halide perovskites are emerging as optoelectronic materials, but they demonstrate poor stability against heat and moisture and are vulnerable to oxidation and photodegradation upon exposure to ultraviolet (UV) light. Herein, for the first time, 1,6-diaminohexane ammonium (HDAD+) is demonstrated to be a unique cation spacer to prepare a two-dimensional Dion–Jacobson phase (DJP) perovskite that is ultimately used to construct a 2D/3D stacking structure. Compared to 3D perovskites and Ruddlesden–Popper phase (RPP)-2D perovskites, the DJP-2D perovskite demonstrates superior UV stability and can efficiently protect the 3D layer underneath from being damaged by the UV light. Moreover, the DJP-2D perovskite can also act as an interfacial layer to passivate the defects located on top of the 3D perovskite, resulting in a notably increased photoluminescence lifetime and suppression of interfacial charge recombination. As a result, the power conversion efficiency (PCE) is enhanced from 19.22% (3D) to 20.31% (2D/3D) and is accompanied by improved moisture and thermal stabilities.

Manganese(II)-doped perovskite nanocrystals (NCs), because of their unique dual-color (from host excitons and Mn-dopants) emission property, are promising materials for various optical applications...

Low‐dimensional hybrid metal halides are emerging as a highly promising class of single‐component white‐emitting materials for their unique broadband emission from self‐trapped excitons (STEs). Despite substantial progress in the development of these metal halides, many challenges remain to be addressed to obtain a better fundamental understanding of the structure–property relationship and realize the full potentials of this class of materials. Here, via pressure regulation, a near 100% photoluminescence quantum yield (PLQY) of broadband emission is achieved in a corrugated 1D hybrid metal halide C5N2H16Pb2Br6, which possesses a highly distorted structure with an initial PLQY of 10%. Compression reduces the overlap between STE states and ground state, leading to a suppressed phonon‐assisted non‐radiative decay. The PL evolution is systematically demonstrated to be controlled by the pressure‐regulated exciton–phonon coupling which can be quantified using Huang–Rhys factor S. Detailed studies of the S‐PLQY relation for a series of 1D hybrid metal halides (C5N2H16Pb2Br6, C4N2H14PbBr4, C6N2H16PbBr4, and (C6N2H16)3Pb2Br10) reveal a quantitative structure–property relationship that regulating S factor toward 28 leads to the maximum emission., This work demonstrates a quantitative relationship between photoluminescence quantum yield (PLQY) and exciton–phonon coupling in a series of 1D hybrid metal halides. Using pressure to regulate the exciton–phonon interaction, a near 100% PLQY of broadband emission from self‐trapped excitons is achieved in a corrugated 1D compound C5N2H16Pb2Br6 whose initial PLQY is 10%.

The growth behavior and electrical transport properties of ZnO films was found to be strongly dependent on the deionized water soaking treatment of 0.7 wt% (111) SrTiO3:Nb substrates. Comparing the ZnO films on soaked SrTiO3:Nb substrates with those on unsoaked ones, the out-of-plane orientation of ZnO films are both along the c-axis, while there is an in-plane rotation of ZnO thin films. According to the variable frequency capacitance–voltage measurements, a much higher interface state density is found in the ZnO/soaked-SrTiO3:Nb heterojunction than that in the ZnO/unsoaked-SrTiO3:Nb heterojunction. Moreover, a rectification and bipolar resistive switching effect were observed in the ZnO/unsoaked-SrTiO3:Nb and ZnO/soaked-SrTiO3:Nb heterojunctions, respectively. The transition from rectification to a bipolar resistive switching effect can be ascribed to an increase of oxygen vacancies, the migration of which plays an important part in the resistive switching.

The continuous phase transformation from the layered structure to the spinel-like phase seriously degrades the electrochemical properties of Li-rich layered oxides in Lithium-ion batteries. Herein, heterostructured Li-rich cathode materials Li[Li 0.2 Ni 0.17 Co 0.07 Mn 0.56 ]O 2 in conjunction with different contents of Zr-containing phosphate (ZCP) coating layers were prepared. The structural and electrochemical characterizations reveal that the ZCP surface layer, which not only prevents electrolyte from eroding the Li-rich core and thus suppressing the fast growth of solid electrolyte interface film and charge transfer resistance on the surface of oxide particles, but also enhances the structural and thermal stabilities of the electrode. As a result, the 3 wt .% coated sample delivers an initial discharge capacity of 216 mAh g ⿿1 with a coulombic efficiency of 80%, compared to 202 mAh g ⿿1 and 71%, respectively, for the bare sample. Particularly, the coated sample demonstrates excellent cycling stability with a capacity retention of 91% within 100 cycles, and higher thermal stability.

Bi2MoO6/BiPO4 composites were successfully synthesized via a simple one-pot hydrothermal method. The samples were characterized by X-ray diffraction, field emission scanning electron microscope, transmission electron microscope and UV–Vis diffuse reflectance spectroscopy. The resulting Bi2MoO6/BiPO4 composites exhibit excellent photocatalytic activity and stability to methylene blue degradation under visible light (λ > 420 nm). The Mo:P = 3:4 sample shows the highest photocatalytic activity at different molar ratios. Different pH values have a considerable effect on the composites. When the pH value is 9, the sample shows the highest photocatalytic activity. The photocatalytic mechanism of Bi2MoO6/BiPO4 composites is mainly due to the higher separation efficiency of electron–hole pairs. A possible pathway of degradation of MB was proposed in this study. The effect of pH on the Bi2MoO6/BiPO4 composites is discussed.

A g-C3N4/bismuth oxychloride (BiOCl) heterojunction was prepared by ultrasonic method. The microstructure, morphology, properties, and photocatalytic activity of the heterojunction were characterized using X-ray diffraction, UV–Vis diffuse reflection spectroscopy, field emission scanning electron microscopy, Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy and electro-chemical experiments. After hybridized with g-C3N4, the absorption edge of g-C3N4/BiOCl showed a red shift that reached 440 nm, with a band gap (E g) calculated to be 2.82 eV. Under visible-light irradiation, the hybrid photocatalyst also showed activity for methylene-blue photodegradation that was approximately 6.3 times higher than the activity of pure BiOCl. The mechanism of photocatalytic activity enhancement involved increased separation of electrons and holes between g-C3N4 and BiOCl. This work significantly contributed to the improvement in photocatalytic activity of BiOCl.