The efficiency of a perovskite solar cell is highly affected by the crystal quality and morphology of its perovskite layer. A facile strategy of using blended organic additives to regulate the film's crystallinity and coverage is studied in this work. The coordination behavior and sublimation temperature of the additives are the essential characteristics which determine the quality of the perovskite films. By introducing a certain amount of MACl, a kind of crystallinity-preferred additive, to partially replace MAAc, a coverage-preferred additive, the film's crystallinity has been obviously improved at no expense of coverage, which results in a lower trap density, higher efficiency and better stability.

The spiropyran-contained nanomicelles with excellent fluorescence emission in colloidal dispersion are fabricated by grafting spiropyran onto a PAA–PS diblock copolymer followed by self-assembling under ultraviolet irradiation in nonpolar solvent of toluene. The spiropyran species is embedded in interior high polar cores of the micelles that can promote the concentration of the merocyanine form of spiropyran. Meanwhile, the embedding of spiropyran inside the micelles produces effects of conformational constraint and uncontact to solvent. The synergy of the above three effects significantly enhances the fluorescence emission of the micelles in colloidal dispersion whereas in the case of the pure spiropyran it shows virtually no emission in toluene. With the aid of ultraviolet and daylight, the fluorescent micelles dramatically shows light-induced size tunability and excellent recyclability, corresponding to the significant change in polarity of the copolymer chain that is caused by the reversible transformation between weak polar spiropyran and zwitterionic merocyanine. Loading and controlled release of rhodamine 6G as a typical polar drug substance is successfully achieved with the micelles. These experimental results may bring about more promising applications of spiropyran species beyond their photochromic properties in microscopic fields such as nanocarrier for drug delivery or micro detector for biosensor.

•Solvent effect on photochromism and solvatochromism of spiropyran is investigated.•A more appropriate definition of positive and negative photochromism is suggested.•A generalized definition of chromism is raised as a reference.•Hansen solubility parameter is employed to analyze solvatochromism.•The irregular stepwise kinetics of spiropyran in nonpolar solvents was observed.The solvent effect on photochromism and solvatochromism of the SP (1′-ethyl-3′, 3′-dimethyl-6-nitrospiro [chromene-2, 2′-indoline]) is investigated in details. The photochromic phenomena indicate that the change of solvents can reverse the thermodynamic equilibrium between the ring-close Spiropyran and ring-open Merocyanine. Therefore, a more appropriate definition is suggested to emphasize the thermodynamic nature of the positive and negative photochromism; furthermore, a generalized definition of chromism is raised as a reference. Hansen solubility parameter is originally employed to analyze the roles of different intermolecular interactions in the solvatochromism of SP in diverse solvents. The kinetics of spiropyran in nonpolar solvents exhibits stepwise first order of reaction that does not follow the regular situation.The photochromic loops of spiropyran in different solvents and the corresponding absorption variation.

•Amine addition during the synthesis of CdSe nanocrystals is investigated.•The particle growth is strikingly accelerated by the in situ amine addition.•OA addition at high temperature leads to the nanoparticles with high quality.•OA addition at low temperature shows also good quality improvement.•ODA might be inappropriate for quality improvement of the nanocrystals.The effect of n-octylamine (OA) and octadecylamine (ODA) addition on the synthesis of CdSe nanocrystals in liquid paraffin via one-pot method is investigated via the measurements of their ultraviolet–visible absorption and fluorescence emission spectra. Our results showed that the in situ added amines can activate the formation reaction of Cd precursor and, as a result, substantially decrease the initial reaction temperature and accelerate the particle growth. By adding OA at high temperature of 200 °C, remarkable improvement on particle quality is achieved, giving relatively narrow size distribution of 33.1 nm and high photoluminescence quantum yield (PLQY) of 81.9% for the CdSe nanoparticles. OA addition at low temperature shows also good quality improvement for the nanoparticles. With regard to the primary amine of ODA, it may be inappropriate for quality improvement of the CdSe nanoparticles from liquid paraffin via one-pot method.

The ternary alloy CdSexS1−x nanocrystals are synthesized in liquid paraffin via one-pot method. The fluorescence emission of the nanocrystals can be altered from violet to green by adjusting the ratio of Se to S without particle size change. By applying subsequent surface modification of the nanocrystals with amine, the fluorescence emission from yellow to red is successfully obtained that is achieved from trap emission enhancement. As a result, the combination of these two approaches makes the fluorescence emission of the ternary alloy CdSexS1−x nanocrystals covering entire visible region from violet to red while their sizes are similar and keep constant.

An excellent fluorescent material derived from spiropyran species was facilely fabricated by appending spiropyran onto the cellulose matrix via a covalent link of an ester carbonyl group. The interior high-polar environment in the porous cellulose matrix can promote the concentration of the merocyanine form; the conformational constraint of cellulose cavities and the elimination of solvent influence can sufficiently develop the quantum yield of merocyanine. In contrast with other spiropyran materials, the synergy of the three different effects can significantly enhance the fluorescent intensity of the spiropyran compound by 1 order of magnitude approximately. These experimental results may bring about more promising applications of spiropyran species beyond their photochromic properties.

•Superhydrophobicity does not definitely mean better anti-corrosion.•Superhydrophobicity works well on anti-corrosion when rolling character maintains.•The application of superhydrophobic surface as anti-corrosion material is limited.This work investigates the anti-corrosion performance of several composite coatings with superhydrophobic and hydrophobic surfaces. The results show that superhydrophobicity does not definitely mean better anti-corrosion than hydrophobicity. The Lotus experiment demonstrates that the advantage of the superhydrophobicity is effective when its rolling characteristic maintains. The analysis on anti-corrosion mechanism reveals that the rough surface may play a double-acting role. This study thus shows that superhydrophobic surface is not always anti-corrosion and its use as anti-corrosion material may therefore be limited.The SEM image of the sample of molar ratio of Ti to CTAB is 1:1 and the profile of the water contact angle is (156°).

•The CdTe NCs are synthesized in aqueous solution with thioglycollic acid.•Zn2+ addition can greatly enhance the fluorescence emission of the NCs.•Zn2+ addition can also make the NCs settle rapidly.•Dissolution in NaOH solution reveals a good reuse of the NCs in a colloid state.The CdTe nanocrystals are synthesized in aqueous solution with a capping ligand of thioglycollic acid. The optical properties of the nanocrystals are investigated by the measurements of ultraviolet–visible absorption and fluorescence emission. Our results show that the addition of Zn2+ can greatly enhance the fluorescence emission of the colloid nanocrystals by one order of magnitude. Meanwhile, it can make the nanocrystals settle rapidly. Thus, the CdTe powder nanocrystals with high fluorescence emission can be easily obtained via a simple centrifugation and subsequent drying process. In addition, the successful dissolution of the powder in NaOH solution reveals a good reuse of the nanocrystals in a colloid state.

The corrosion resistance of the three-layer superhydrophobic composite coating on carbon steel in sterilized seawater is investigated using electrochemical and contact angle measurements. The composite coating consists of Ni–P, TiO2/ZnO and octadecyltrimethoxysilane (ODS) molecules. The corrosion resistance of the composite coating is estimated by electrochemical impedance spectroscopy (EIS) and polarization curves. The results show that forming a bi-layer or three-layer composite coating on carbon steel considerably improves the corrosion resistant in sterilized seawater. The corrosion mechanism of the composite coating on carbon steel is proposed through the equivalent circuit.

In this paper a comparative study is carried out on the CdSe QDs synthesized from water and ethanol. Our purpose is to present an insight understanding on how hydrogen bonds affect particle agglomeration and consequently photoluminescence (PL) behavior of the QDs. In comparison with those from water, the CdSe QDs from ethanol show super PL with high brightness. Detailed characterization gives the only difference of large agglomerates presented in the QDs from ethanol. The TEM and HRTEM observations reveal a tri-level microstructure for the QDs from ethanol while in the case of those from water it is bi-level. With these direct evidences weak hydrogen bond of TGA with ethanol is proposed to be responsible for these large agglomerates and consequently super PL behavior. Additional investigations on some other alcohols of methanol, n-propanol, and i-butanol yield positive results and confirm the truth of our proposal.

Luminescent CdSe quantum dots are synthesized using ethanol as a solvent instead of commonly-used water or organic compounds with long alkyl chains. The strong fluorescent emission of the quantum dots is expectedly related to particle agglomeration that dramatically form a tri-level microstructural characteristic.Highlights► Luminescent CdSe QDs are synthesized using ethanol as a solvent. ► The QDs agglomerate to form a tri-level microstructural characteristic. ► The strong fluorescent emissions are expectedly related to such microstructure.

The Ni–P and Ni–P–polytetrafluoroethylene (PTFE) coatings with various PTFE contents were electroless deposited on carbon steel and characterized through X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The microstructural morphologies of the coatings significantly varied with the PTFE content. As a result, the electrochemical anticorrosion capabilities were seriously decreased with the increase of the PTFE content. The coating with a trace PTFE (PTFE emulsion concentration of 0.2 mL/L in the plating bath) possessed excellent anticorrosion both in sterilized and unsterilized seawater which has been attributed to the absence of nano pores blocked by the incorporated trace PTFE nano particles.

The microstructural effect on the crack propagation was investigated using two kinds of micro–nano ZTA composites made of micro-Al2O3 and nano-ZrO2 particles. The results indicated that with low ZrO2 content (10 vol.%) in the composite the presence of both large ZrO2 particles located along Al2O3 grain boundary and very fine ZrO2 particles embedded inside of Al2O3 grains was responsible for the appearance of transgranular fracture. Consequently, the composite showed a typical R-curve of rising up more quickly and better toughness than the composite with high ZrO2 content (20 vol.%). The crack propagation inside of Al2O3 grains, depending on the nature of residual stress produced due to the thermal mismatch of Al2O3 and ZrO2 as well as the phase transformation of ZrO2 from tetragonal to monoclinic, was found to be in the way of either bypassing or splitting ZrO2 particles.