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Electrochromic devices (ECDs) have attracted substantial attention on account of their unique characteristics and prosperous applications. However, their monotonous color modification remains a momentous challenge that significantly restricts their application scope. Integrating structural colors that arise from the interaction between light and periodic micro/nanostructures with electrochromic materials (ECMs) turns out to be an effective approach to enhancing the comprehensive performance of ECDs more than the coloration effectiveness. This review provides an overview on the recent burgeoning development of structural color ECDs regarding strategies and applications. The performance parameters of ECDs and physical principles regarding the generation of structural colors are introduced. Then, strategies that introduce structural colors into ECDs are discussed according to the category of chromogenic micro/nanostructures, namely, gratings, (single‐layer and multilayer) thin films, photonic crystals, plasmonic metasurfaces, and composite structures. The current state‐of‐the‐art research activities of structural color ECDs for display application including segmented and pixelated devices are also presented. Additionally, the future perspective of structural color ECDs with respect of major challenges and potential solutions is proposed. [ABSTRACT FROM AUTHOR]

2D organic semiconductor crystals (2D OSCs) are vital for high‐performance electronic and optoelectronic devices owing to their unique material merits. However, it is still challenging to fabricate high‐quality and large‐scale ultrathin 2D OSCs with controllable molecular layers due to the disordered molecular deposition and uncontrollable mass transport in solution‐processing fabrication. Here, a vapor‐induced meniscus modulating strategy for preparing unidirectional and stable Marangoni flow to guide contactless meniscus evolution is reported, which ensures uniform mass transport and ordered molecular deposition to achieve high‐quality ultrathin 2D OSCs. Both the surface tension difference and the substrate wettability are critical to meniscus formation, which results in various meniscus deformation states and film morphologies. Based on the optimized vapor‐solvent system, ultrathin 2D OSCs of C8‐BTBT with precise layer definition are prepared controllably. The discrepancies in liquid film height and solute concentration are decisive in controlling the molecular scale thickness ranging from mono to a few layers. Moreover, the layer‐dependent electronic and optoelectronic properties of the ultrathin films are systematically investigated. Notably, high‐performance polarization‐sensitive solar‐blind photodetectors are achieved with a dichroic ratio of photocurrent up to 2.26, and the corresponding polarimetric image sensor exhibits superior solar‐blind polarization imaging capability thanks to the high crystalline quality. [ABSTRACT FROM AUTHOR]

A new crystal form of 1D perovskite (pyrrolidinium)PbI3 (orthorhombic phase) is synthesized and characterized. The 1D perovskite has a good film formability by solution spin coating and is in situ transformed to 3D CH3NH3PbI3 via the organic cation exchange approach in CH3NH2 atmosphere, which is dense and uniform. The converted 3D perovskite film is used as a light absorber, and the corresponding perovskite solar cell shows a power conversion efficiency of up to 19.2% under simulated 1 sun AM1.5G illumination (100 mW cm−2). [ABSTRACT FROM AUTHOR]

Tin‐based halide perovskite materials have been successfully employed in lead‐free perovskite solar cells, but the overall power conversion efficiencies (PCEs) have been limited by the high carrier concentration from the facile oxidation of Sn2+ to Sn4+. Now a chemical route is developed for fabrication of high‐quality methylammonium tin iodide perovskite (MASnI3) films: hydrazinium tin iodide (HASnI3) perovskite film is first solution‐deposited using presursors hydrazinium iodide (HAI) and tin iodide (SnI2), and then transformed into MASnI3 via a cation displacement approach. With the two‐step process, a dense and uniform MASnI3 film is obtained with large grain sizes and high crystallization. Detrimental oxidation is suppressed by the hydrazine released from the film during the transformation. With the MASnI3 as light harvester, mesoporous perovskite solar cells were prepared, and a maximum power conversion efficiency (PCE) of 7.13 % is delivered with good reproducibility. [ABSTRACT FROM AUTHOR]

Defects from grain interiors and boundaries of perovskite films cause significant nonradiative recombination energy loss, and thus perovskite films with controlled crystallinity and large grains is critical for improvement of both photovoltaic performance and stability for perovskite-based solar cells. Here, a methylamine (MA0) gas-assisted crystallization method is developed for fabrication of methylammonium lead iodide (MAPbI3) perovskite films. In the process, the perovskite film is formed via controlled release of MA0 gas molecules from a liquid intermediate phase MAPbI3·xMA0. The resulting perovskite film comprises millimeter-sized grains with (110)-uniaxial crystallographic orientation, exhibiting much low trap density, long carrier lifetime, and excellent environmental stability. The corresponding perovskite solar cell exhibits a power conversion efficiency (PCE) of ~ 21.36%, which is among the highest reported for MAPbI3-based devices. This method provides important progress towards the fabrication of high-quality perovskite thin films for low-cost, highly efficient and stable perovskite solar cells. Suppressing grain boundaries and defects in perovskite solar cells remains a quest to address the efficiency and stability issues. Here, the authors use methylamine gas for assisting the growth of uniaxial-oriented perovskite thin films with millimeter-sized grains. [ABSTRACT FROM AUTHOR]

A spiropyran molecule bonded with ferrocene (SPFc) was synthesized as data storage medium. Optical recording pattern was obtained through the reversible modulation of UV and visible light on the SPFc film, which exhibited good reversibility compared with the spiropyran without ferrocene moiety. In addition, the SPFc thin film also possessed reversible electrical switching property with high ON/OFF ratio, low threshold voltage, and long retention time. Accordingly, reliable, stable, and reversible nanoscale data storage was achieved on the SPFc thin film by scanning tunneling microscopy. The results will be significant to develop multifunctional molecule and reversible multimode data storage. [ABSTRACT FROM AUTHOR]

To improve the stability of organic multifunctional materials and enhance the ON/OFF ratio, a donor-π-acceptor molecule with the triphenylamine (TPA) unit is designed and synthesized. The TPA unit can effectively stabilize the charge transferred state, and the thin film shows excellent bistable electronic switching behavior with high ON/OFF current ratio of about 105. Meanwhile, reversible and stable nanometer-scale data storage is realized on the thin film by applying pulsed voltages, and optical information storage is achieved simultaneously by utilizing fluorescence changes under UV irradiation. [ABSTRACT FROM AUTHOR]

An active plasmonic device is fabricated by introducing a photonic crystal structure into an energy transfer system across a metal film. It is demonstrated that the stopband of the photonic crystal plays a key role in improving the efficiency of the energy transfer. A well-designed stopband can enhance the emission intensity of the device by over ten times compared with that of a similar planar device. Active plasmonic devices based on photonic crystal structure will provide promising materials for highly efficient optic devices. [ABSTRACT FROM AUTHOR]

This letter reports the synthesis of an organic molecule N,N′-bis (salicylidene)-1,6-hexanaphthenediamine (BSH) and the study of its electrical properties. Reversible electrical bistable behavior was observed both in BSH organic thin film on indium tin oxide substrate and in a crossbar device fabricated via standard integrated circuit processing with this thin film. The proton transfer model, induced by a bias higher than the switch threshold voltage, was employed to explain the electrical bistable phenomenon. This electrical bistability of BSH molecules is a key property for potential applications in organic nonvolatile memories and programable switches. [ABSTRACT FROM AUTHOR]

A systematic understanding of perovskite single crystal is critical for the development of high-performance functional devices. We outline the synthesis strategies, unique characteristics, and optoelectronic applications of perovskite single crystals with diverse dimensions, including 0D perovskite QDs, 1D micro/nanowires arrays, 2D micro/nanoplates arrays and single-crystal films, and 3D micro/nanoscale single-crystal structures, providing guidelines for the application of integrated devices. [Display omitted] Lead halide perovskite single crystals have emerged as promising candidates for high-performance optoelectronic devices because of their superior optoelectronic properties. To date, much literature has reported the fabrication of various perovskite single-crystal structures. However, it still lacks effective rationalization and a comprehensive understanding of the relationship between the structural characteristics and functional properties of the perovskite single crystals, which is of great significance for fabricating perovskite single crystals-based high-performance optoelectronic devices. In this review, we give a comprehensive overview of the synthesis of perovskite single crystals with diverse dimensions, including 0D perovskite quantum dots (QDs), 1D micro/nanowires, 2D micro/nanoplates and single-crystal thin films (SCTFs), and 3D micro/nanoscale single-crystal structures. The relationship between the dimensional structure and properties of the perovskite single crystals is discussed in detail. Dimensional requirements for different optoelectronic applications are systematically summarized. Finally, perspectives on remaining challenges and future opportunities are highlighted. [ABSTRACT FROM AUTHOR]

Highlights • In-situ gas-solid reaction for fabrication of AgSbS 2 thin films. • Phase-pure AgSbS 2 was obtained without impurities. • AgSbS 2 films with excellent photoresponse and photostability. Abstract This work reports the fabrication of AgSbS 2 semiconductor films via in-situ gas-solid reaction approach, including sequential solution-deposition of AgNO 3 and SbCl 3 percursor solutions on mesoporous TiO 2 substrates, and subsequent sulfurization of the prepared films at H 2 S atmosphere. The resultant TiO 2 /AgSbS 2 films show broad spectral absorption ranged from 350 nm to 800 nm with a band gap of 2.01 eV. X-ray photoelectron spectroscopy (XPS) spectra confirm the fabrication of phase-pure AgSbS 2 without any impurity. Furthermore, the devices with a structure of fluorine-doped SnO 2 (FTO)/TiO 2 /AgSbS 2 /Au have been prepared, exhibiting quick interfacial charge transfer and electron injection process with excellent photoresponse and high photostability. [ABSTRACT FROM AUTHOR]

In this report, a facile, low-cost, in situ gas-solid reaction method has been successfully employed for the deposition of copper antimony sulfide (CuSbS 2 ) semiconductor film, where copper and antimony metal precursor is first spin-coated on the TiO 2 substrate, followed by reaction with H 2 S gas and further thermal annealing. The CuSbS 2 film shows broad absorption ranged from 400 nm to 830 nm with a band gap of 1.57 eV. X-ray photoelectron spectroscopy (XPS) analysis confirms valence states of the synthetic samples for Cu + , Sb 3+ and S 2− , verifying phase-pure CuSbS 2 . Besides, the CuSbS 2 films made by one-step method show good photoelectric property with a high potential as photovoltaic absorber. [ABSTRACT FROM AUTHOR]

Thoughpatterned ultrathin polymer films (<100 nm) are of greatimportance in the fields of sensors and nanoelectronic devices, thefabrication of patterned ultrathin polymer films remains a great challenge.Herein, patterned ultrathin polymer films are fabricated facilelyon hydrophobic substrates with different hydrophilic outline patternsby the pinning of three-phase contact lines of polymer solution onthe hydrophilic outlines. This method is universal for most of thewater-soluble polymers, and poly(vinyl alcohol) (PVA) has been selectedas a model polymer due to its biocompatibility and good film-formingproperty. The results indicate that the morphologies of ultrathinpolymer films can be precisely adjusted by the size of the hydrophilicoutline pattern. Specifically, patterned hydrophilic outlines withsizes of 100, 60, and 40 μm lead to the formation of concave-shapedultrathin PVA films, whereas uniform ultrathin PVA films are formedon 20 and 10 μm patterned substrates. The controllabilitiesof morphologies can be interpreted through the influences of the sliplength and coffee ring effect. Theoretical analysis shows that whenthe size of the hydrophilic outline patterns is smaller than a criticalvalue, the coffee ring effect disappears and uniform patterned ultrathinpolymer films can be formed for all polymer concentrations. Theseresults provide an effective methodology for the fabrication of patternedultrathin polymer films and enhance the understanding of the coffeering effect. [ABSTRACT FROM AUTHOR]

Highlights: [•] A surface-mediated buckling process via thermal annealing for fabricating morphology-controllable particles was reported. [•] Dimple-like particles and back-rest chair-like particles were obtained, and the indentation depth of these particles could be tuned. [•] Water adhesion-tunable films were built by the morphology-controllable particles. [ABSTRACT FROM AUTHOR]

Abstract: In this work, we present a facile approach on the remarkable enhancement of fluorescent signal by heterostructure colloidal photonic crystals (PCs) with dual stopbands. The intensity of fluorescent medium on heterostructure PCs with dual stopbands overlapping the excitation wavelength and the emission wavelength of fluorescent medium can be up to 162-fold enhancement in comparison to that on the control sample. Otherwise, parameters of heterostructure PC films such as film thickness or stacking order have important effects on fluorescent signals. The method will be of great significance for developing the highly sensitive fluorescence-based detection. [Copyright &y& Elsevier]