We propose a phase-shifting interferometry technique using only two in-line phase-shifted self-interference holograms. There is no requirement for additional recording or estimation in the measurement. The proposed technique adopts a mathematical model for self-interference digital holography. The effectiveness of the proposed technique is demonstrated by experiments on incoherent digital holographic microscopy and color-multiplexed fluorescence digital holography with computational coherent superposition. Two-color-multiplexed four-step phase-shifting incoherent digital holography is realized for the first time, to the best of our knowledge, using the proposed technique. (C) 2021 Optical Society of America

We present color fluorescence imaging using an incoherent digital holographic technique in which holographic multiplexing of multiple wavelengths is exploited. Self-interference incoherent digital holography with a single-path in-line configuration and the computational coherent superposition scheme are adopted to obtain color holographic three-dimensional information of self-luminous objects with a monochrome image sensor and no mechanical scanning. We perform not only simultaneous color three-dimensional sensing of multiple self-luminous objects but also color fluorescence imaging of stained biological samples. Color fluorescence imaging with an improved point spread function is also demonstrated experimentally by adopting a Fresnel incoherent correlation holography system. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

In this research, organic-inorganic hybrid materials that enable the detection and manipulation of "invisible light"such as weak light, polarized light, and near-infrared (NIR) light are prepared and optoelectronic devices based on these materials are developed. The photoelectric conversion or energy transfer process resulting from light absorption is precisely controlled at the heterointerface of organic- inorganic hybrid structures, which enables the highly efficient amplification, conversion, and detection of invisible light under normal temperatures and pressures. Here, novel optical functions and devices based on organic-inorganic hybrid structures and interfaces are presented. For instance, in a hybrid structure in which organic molecules and inorganic semiconductors are chemically bonded, photocurrent was amplified more than 2000-fold at their heterointerface, resulting in highly sensitive photodetection at a low voltage (&lt
1 V). As a novel device structure for the direct detection of circularly polarized light with high sensitivity, an inorganic crystal thin film with a one-dimensional helical structure was fabricated via interaction with organic chiral molecules. For NIR light, dye-sensitized up-conversion nanoparticles that can convert NIR light as weak as sunlight into visible light with high efficiency were developed and incorporated into a perovskite-based visible-light detector. This device detected light in the NIR region through energy conversion from NIR to visible light. And also, NIR light was promoted as ultra-bright luminescence by one-photon absorption two-photon emission (quantum-cutting) process in heterometal hybridized crystal thin films. The light-emitting diode was fabricated and demonstrated 6% external conversion efficiency of field emission in the NIR region.

Surface modification of 3D hybrid perovskites using 2D perovskites, such as phenethylamine halides (PEAX), increases the overall power conversion efficiency (PCE) and stability of perovskite solar cells (PSCs). The effect is based on a surface passivation phenomenon where PEAX is in direct contact with the perovskite and hole transport layer (HTL). However, it is herein observed that the PCE of PSCs containing PEAX increases significantly when they are not in direct contact with either the bottom layers (perovskites) or top layers (HTLs). Moreover, the highest PCE (&gt
22%) is obtained for the PSCs when PEAX is not in contact with HTLs by using poly(methyl methacrylate) (PMMA). Photoemission measurements reveal that the shift of the highest occupied molecular orbital of the hole transporting material (a donor-acceptor-donor molecule synthesized for the study) to a deeper level results in an increased hole transfer at the perovskite/HTL interface leading to an improved device performance. It is proposed that PEAX acts as dipoles aligned between perovskite and HTL resulting in a shift in the energy levels. The combination of PEAX/PMMA at the interface enables high open-circuit voltage (1.19V) close to the Shockley–Queisser limit for the triple-cation (Cs-MA-FA) perovskites (bandgap, 1.51 eV).

We present phase-shifting interferometry techniques applied for multidimensional incoherent digital holography and toward ultimately low light-intensity sensing. Using incoherent holography with multiwavelength-multiplexed phaseshifting interferometry that is termed computational coherent superposition (CCS), full-color three-dimensional (3D) information of an incoherent object can be obtained from the recorded wavelength-multiplexed self-interference holograms. Furthermore, an optical setup of incoherent holography based on CCS is implemented as a palm-sized incoherent digital holographic sensing system, termed "Holosensor."Using incoherent holography with single-shot phase-shifting holography, high-speed 3D motion-picture imaging has been demonstrated. Phase-shifting interferometry is also a powerful 3D sensing technique for ultimately low light-intensity conditions.

Oligomeric-brush chains of helical lanthanide (Ln) complexes retain their structural and luminescent behavior after coating onto magnetic nanoparticles (MNPs) consisting of Fe3O4 covered with silicate. It is one of the type of bifunctional NPs exhibiting luminescence of Ln and superparamagnetism of Fe3O4. In comparison to a simple monolayer of complexes adsorbed on a modified surface, a layer made of luminescent chains allowed us to obtain a more intensive red/green luminescence originating from Eu3+/Tb3+ ions, and at the same time, no visible increase in particle size (compared to Fe3O4@silica particles) was observed. The luminescent properties of the Tb3+ complex were altered by MNPs; the decrease of the luminescence was not as large as expected, the excitation spectrum changed significantly, and the average luminescence lifetime was much longer at room temperature. Surprisingly, this phenomenon was not observed at 77 K and also did not occur for the Eu3+ complexes. The possibility to stack building blocks in a chain using complexes of different lanthanide ions can be used to design novel multifunctional nanosystems.

Detection of circularly polarized light (CPL) has a high potential for development of various optical technologies. Conventional photodetectors require optical polarizers on the device to detect polarized light, and this causes substantial losses of sensitivity and resolution in light detection. Here, we report direct CPL detection by a photodiode using a helical one-dimensional (1D) structure of lead halide perovskites composed of naphthylethylamine-based chiral organic cations. The 1D structure with face-sharing (Pbl(6))(4-) octahedral chains whose helicity is largely affected by chiral cations shows intense circular dichroism (CD) signals over 3000 mdeg at 395 nm with the highly anisotropy factor (g(CD)) of 0.04. This high CD enables photocurrent detection with effective discrimination between left-handed and right-handed CPLs. The CPL detector based on this 1D perovskite achieved the highest polarization discrimination ratio of 25.4, which largely surpasses the direct detecting CPL devices (<4) using chiral plasmonic metamaterials and organic materials.

Quantum cutting is an attractive optical phenomenon where one high-energy photon is converted into two low-energy photons, resulting in photoluminescence quantum yields (PLQYs) above 100%. In this report, we demonstrate a novel approach to enhance the quantum cutting energy transfer from an all-inorganic perovskite (CsPbCl3) to ytterbium (Yb3+) and erbium (Er3+) ions as near-infrared (NIR) emitters by using the highly orientated crystalline film. Yb3+ ions are fixed in the neighborhood of the CsPbCl3 lattice by preparing a one-to-one layer arrangement consisting of quasi-2D CsPbCl3 perovskite and Yb3+ layers. The successful preparation of layer arrangements resulted in the highly sensitized luminescence of Yb3+ by CsPbCl3 with NIR PLQYs exceeding 130%, which is attributed to quantum cutting. In addition, Er3+ luminescence at 1540 nm is acquired by the co-existence of Er3+ with Yb3+ in a layer, which is a result of the intralayer metal-to-metal energy transfer from Yb3+ activated by CsPbCl3 via the interlayer quantum cutting process. The PLQY of Er3+ luminescence reaches to 12.6%, which is the highest value ever observed for Er3+ compounds, resulting from the efficient interlayer quantum cutting process over 100% and the following intralayer resonance metal to metal energy transfer with the efficiency over 80%.

Compositional engineering and interfacial modifications have played pivotal roles in the accomplishment of high-efficiency perovskite solar cells (PSCs). Different interfaces in the PSCs influence the performance remarkably either by altering the crystallization of the active material or shifting the energy levels or improving the electrical contact. This work reports how a thin layer of cesium acetate on the TiO2 electron transport layer (ETL) induces generation of a PbI2-rich methylammonium lead iodide (MAPbI(3)) composition at the ETL/MAPbI(3) interface, which downshifts the conduction band level of MAPbI(3) to create an energy level gradient favorable for carrier collection, resulting in higher photocurrent, fill factor, and overall power conversion efficiency.

We propose a holographic technique by which multiwavelength three-dimensional spatial information is obtained with both a single-shot exposure of a monochrome image sensor and an in-line holographic multiplexing scheme. We develop a specially designed monochrome image sensor with a wavelength-dependent phase-modulation array, which is used to obtain the holographic information required for the proposed technique. The proposed technique is applicable for not only laser holography but also spatially and temporally incoherent holography. Its validity is experimentally demonstrated by constructing a color-multiplexed fluorescence digital holographic microscope and a multicolor incoherent digital holography system with a white-light source. VC 2020 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

CsPbI2Br perovskite solar cells have attracted much attention because of the rapid development in their efficiency and their great potential as a top cell of tandem solar cells. However, the VOC outputs observed so far in most cases are far from that desired for a top cell. Up to now, with various kinds of treatments, the reported champion VOC is only 1.32 V, with a VOC deficit of 0.60 V. In this work, we found that aging of the SnCl2 precursor solution for the electron-transporting layer can promote the VOC of CsPbI2Br solar cells by employing a dopant-free-polymer hole transport material (HTM) over 1.40 V and efficiency over 15.5% with high reproducibility. With the champion VOC of 1.43 V, the VOC deficit was reduced to <0.50 V, which is achieved for the first time. This simple technique of SnCl2 solution aging forms a uniform and smooth amorphous SnO
x
film with pure Sn4+, elevates the conduction band of SnO
x
, and reduces the interfacial gaps and the trap state density of the device, resulting in enhancement in average VOC from ∼1.2 V in the nonaged case to ∼1.4 V in the aged case. Furthermore, the device using an aged SnCl2 solution also exhibits a much better long-term stability than that made of the fresh solution. These achievements in dopant/additive-free CsPbI2Br solar cells can be useful for future research on CsPbI2Br and tandem solar cells.

Interfacial engineering, grain boundary, and surface passivation in organic-inorganic hybrid perovskite solar cells (HyPSCs) are effective in achieving high performance and enhanced durability. Organic additives and inorganic doping are generally used to chemically modify the surface contacting charge transport layers, and/or grain boundaries so as to reduce the defect density. Here, a simple but tricky one-step method to dope organic-inorganic hybrid perovskite with Ge for the first time is reported. Unlike Ge doping to all-inorganic perovskites, application of GeI2 in organic-inorganic perovskite precursors is challenging due to the extremely poor solubility of GeI2 in hybrid perovskite ink, leading to failure in the formation of uniform films. However, it is found that addition of methylammonium chloride (MACl) into the precursor remarkably increases the solubility of GeI2. This MACl-assisted Ge doping of hybrid perovskites produces high-quality crystalline film with its surface passivated with nonvolatile GeI2 (GeO2) and the volatile MACl additive also improves the uniformity of GeO2 distribution in the perovskite films. The resulting Ge-doped mixed cation and mixed halide perovskite films with composition FA(0.83)MA(0.17)Ge(0.03)Pb(0.97)(I0.9Br0.1)(3) show superior photoluminescence lifetime, power conversion efficiency above 22%, and greater stability toward illumination and humidity, outperforming photovoltaic properties of HyPSCs prepared without the Ge doping.

Near-infrared (NIR) light emitting diodes (LEDs) with the emission wavelength over 900 nm are useful in a wide range of optical applications. Narrow bandgap NIR emitters have been widely investigated using organic compounds and colloidal quantum dots. However, intrinsically low charge mobility and luminescence efficiency of these materials limit improvement of the external quantum efficiency (EQE) of NIR LEDs, which is far from practical applications. Herein, a highly efficient NIR LED is demonstrated, which is based on an energy transfer from wide bandgap all inorganic perovskite (CsPbCl3) to ytterbium ions (Yb3+) as an NIR emitter doped in the perovskite crystalline film. High mobility of electrically excited carriers in the perovskite crystalline film provides a long carrier diffusion and enhances radiative recombination of an emission center due to minimized charge trapping losses, resulting in high EQE value in LEDs. The NIR emission of Yb3+ at around 1000 nm is found to be sensitized by CsPbCl3 thin film with a photoluminescence quantum yield over 60%. The LED based on Yb3+-doped CsPbCl3 film exhibits a high EQE of 5.9% with a peak wavelength of 984 nm, achieved by high carrier transporting ability and effective sensitized emission property in the solid-film structure.

© 2020 SPIE. Phase-shifting interferometry selectively extracting wavelength information, which is termed the computational coherent superposition (CCS) of multiple wavelengths, was first proposed in 2013. In this proceeding, phase-shifting interferometry and its application to digital holography are described. We apply CCS to self-interference incoherent color holography and construct single-path, mechanical-motion-free, wavelength-multiplexed, incoherent color digital holographic microscopy systems. Also, we numerically investigate quantum fluctuation in phase-shifting interferometry with the aim of recording weak light such as natural light and nonlinear light. After that, we briefly discuss the difference between color digital holography with single-shot CCS and color digital holography with single-shot phase-shifting interferometry and a Bayer color image sensor.

<p>Several aspects for the control of luminescence intensity, selectivity and sharpness of the bands were discussed by using helicate Eu, Pr and Gd complexes with a series of hexadentate ligands.</p>

© 2019 American Chemical Society. Lanthanide (Ln) based luminescent materials are experiencing an increasing interest in their applications in several fields. In this study, we report a series of new lanthanide-oligomeric brush films, supported on quartz substrates and prepared using a layer-by-layer method (LbL). Oligomeric brush films are composed of small oligomers from our previously reported coordination polymers [x-EuL] and [x-TbL] (with x = 1, 3, and 5 generations of Ln complexes), which are grown perpendicularly from a carboxylate self-assembled monolayer. Oligomers composed of our previously described helical lanthanide complex LnL (Ln: Eu and Tb) as a luminescent moiety and benzene-1,4-dicarboxylate acid (bdc) used as a linker. Mixed films having the fifth-generation Ln complexes composed of equimolar mixture of Eu and Tb ions were prepared. Oligomeric brush films are highly transparent and exhibited a colored emission under UV irradiation. Pure Ln (Eu or Tb) films showed a strong luminescence from the Ln ions. Their luminescent properties depended on the number of lanthanide layers in the films composed of the first to third generations of lanthanide complexes. Then, the increase of the complex layers induced no difference in the luminescent properties. An energy transfer from Tb to Eu ions in the mixed films indicated a short distance between lanthanide ions of a fifth layer. The structural analysis together with the observed luminescent properties and some previous studies allowed to clarify the disposition of the oligomers in the films.

<p>The complexation in LB films induces the linearly polarized luminescence of europium by the excited 1-naphtoate ligand.</p>

We fabricated luminescent chemical vapor deposition-grown monolayer graphene sheets with an adsorbed europium complex, EuLC18, and characterized their luminescence properties. The EuLC18/graphene sheets clearly showed several photoluminescence peaks in a wavelength region from 580 to 694 nm, which were attributed to the ff transitions of the Eu ion. Luminescence was obtained via a photo-antenna effect, in which the ligands of EuLC18 absorbed the photo-excitation energy and transported it to the Eu excitation. Although the absolute luminescence quantum yield of the EuLC18/graphene sheet was as low as 0.5% due to the interaction between graphene and EuLC18, we demonstrated that graphene sheets can be made luminescent simply through adsorption of the luminescent Eu complex on the graphene surface.

A simple device structure composed of an interfacial Eu2+/3+ complex on a mesoporous TiO2 film is developed by a solution process and acts as the high-performance photodetector with photomultiplication phenomena. The electron transfer from the photoexcited organic ligand, 2,2′:6′,2″-terpyridine (terpy), as a photosensitizer to TiO2 is accelerated by the reduction level of Eu3+/2+ ions chemically bonding among terpy and TiO2, resulting in the generation of a large photocurrent. It is worth noting that its external quantum efficiency is in excess of 105% under applied reverse bias. The corresponding responsivity of the device is also determined to be 464 A/W at an irradiation light intensity of 0.7 mW/cm2 (365 nm), which is more than 3 orders of magnitude larger than those of inorganic photodetectors. A dark current of the device can be reduced to 10-9 A/cm2 by introducing a Eu oxide thin-film layer as a carrier blocking layer at the interface between transparent conducting oxide (TCO) and the TiO2 layer, and the specific detectivity reaches 5.2 × 1015 jones at 365 nm with -3 V. The performance of our organic-inorganic hybrid photodetector surpasses those of existing ultraviolet photodetectors.

© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim A [7]helicene bis-ruthenium complex, with one ruthenium atom bound to the cyclopentadienyl (Cp) ring and the other coordinated to the arene ring at the edge of the helicene, was synthesized. This complex showed phosphorescence both in butyronitrile (Φ=31 %, 77 K) and in the solid state (Φ=18 %, 77 K). The two non-equivalent ruthenium metal atoms, attached to the helicene ligand, interact with each other upon photoabsorption and emission.

The luminescence of a Eu complex (EuL) is enhanced by stabilization of the coordination structure in highly viscous ionic liquids. The EuL was found to maintain a stable single helical structure both in organic solvents and in the ionic liquids [BMIM][PF6] and [EMIM][PF6]. A colorless solution of EuL dissolved in [BMIM][PF6] exhibits bright red luminescence with a quantum yield of 32.3%, a value that is much higher than that in acetonitrile (12%). Estimated rate constants for the energy relaxation pathway indicate that the energy transfer efficiency is enhanced in [BMIM][PF6] as a result of the suppression of molecular fluctuations in the ligands. Additionally, a highly luminescent helical structure is preserved in [EMIM][PF6] up to 120-C.

Five Eu complexes with long alkyl chain groups, abbreviated as EuLCx ("x" indicates the number of methylene groups: x = 8, 12, 14, 18, and 22), were synthesized to evaluate their structural and luminescence properties in chloroform. The mother helicate Eu complex, EuL, which has two bipyridine moieties bridged by an ethylenediamine, has been previously reported. A reduced form in which the azomethine groups of L also coordinated to the Eu ion, EuLH, was newly prepared. EuLH also adopts a helicate molecular structure based on single crystal X-ray structural analysis. The amine hydrogens of the bridging ethylenediamine of LH are active sites for substitution and were exchanged with five different alkyl chains to form EuLCx. Luminescence band positions and shapes of EuLCx in chloroform were completely identical, with a quantum yield of 37.1 ± 1.2 and a lifetime of around 1.25 ms. This indicates that the environments surrounding the Eu ion in the various complexes are all similar. Luminescence quantum yields of TbLH and TbLC18 are also strengthened, 48.7% in acetonitrile and 55% in chloroform, respectively. Potential energy surfaces were also described by using density functional theory, suggesting the possibility of a 1:2 complex of Eu and the ligand as a main luminescent species in solutions. This 1:2 complexation forms Eu-oxygen coordination using acyl groups. It indicates that the acyl group modification results in a different structure from the mother complexes.

Deuteration and/or polymorphism effects on the ff emission of lanthanide complexes were discussed by using phenanthroline (phen) and deuterated phenanthroline (phen-d(8)) complexes with Eu, Tb, Gd and Tm ion as a center metal. Lanthanide complexes with phen or phen-d(8) form polymorphism such as phase Ha and I. The ratio of polymorphism IIa to I of Gd or Tm complexes with phen was newly estimated by a synchrotron XRPD. From the measurement of luminescence spectra, lifetimes and absolute quantum yields at room temperature and 77 K, it was found that the ff emissions of above lanthanide complexes were explained by their energy relaxation process through intermolecular energy transfer and the polymorphism effects. Luminescence of Eu was intensified by the deuteration of phen, due to deactivation with the overtones of C-H/D vibrations, and each luminescence quantum yield of two phase was theoretically estimated. Tb had no influence clearly by the deuteration in phen, but did by the polymorphisin formation. Blue luminescence of Tm was observed in both phen/phen-d(8) complexes. Furthermore, the luminescence component ratios of lanthanide complexes with phen corresponded to the ratios from the observation of XRD. (C) 2016 Elsevier B.V. All rights reserved.

The formation and control of a room-temperature magnetic order in two-dimensional (2D) materials is a challenging quest for the advent of innovative magnetic- and spintronic-based technologies. To date, edge magnetism in 2D materials has been experimentally observed in hydrogen (H)-terminated graphene nanoribbons (GNRs) and graphene nanomeshes (GNMs), but the measured magnetization remains far too small to allow envisioning practical applications. Herein, we report experimental evidences of large room-temperature edge ferromagnetism (FM) obtained from oxygen (O)-terminated zigzag pore edges of few-layer black phosphorus (P) nanomeshes (BPNMs). The magnetization values per unit area are similar to 100 times larger than those reported for H-terminated GNMs, while the magnetism is absent for H-terminated BPNMs. The magnetization measurements and the first-principles simulations suggest that the origin of such a magnetic order could stem from ferromagnetic spin coupling between edge P with O atoms, resulting in a strong spin localization at the edge valence band, and from uniform oxidation of full pore edges over a large area and interlayer spin interaction. Our findings pave the way for realizing high-efficiency 2D flexible magnetic and spintronic devices without the use of rare magnetic elements.

An interfacial coordination nanoparticle successfully exhibited an upconversion blue emission excited by very low-power light irradiation, such as sunlight. The interfacial complex was composed of Yb ions and indigo dye, which formed a nano-ordered thin shell layer on a Tm2O3 nanoparticle. At the surface of the Tm2O3 particle, the indigo dye can be excited by non-laser excitation at 640 nm, following the intramolecular energy transfer from the indigo dye to the Yb ions. Additionally, the excitation energy of the Yb ion was upconverted to the blue emission of the Tm ion at 475 nm. This upconversion blue emission was achieved by excitation with a CW Xe lamp at an excitation power of 0.14 mW/cm(2), which is significantly lower than the solar irradiation power of 1.4 mW/cm(2) at 640 +/- 5 nm.

The luminescence and structure of a water-soluble helicate Eu complex with L-COOH, which is a hexadentate ligand with COOH groups, were examined in solutions of various pH. The Eu complex EuLCOOH is more than eight-coordinated around Eu, and one of the two carboxylate groups is not bound, even in the powdered state, based on the FT-IR measurement. The synchrotron X-ray powder diffraction peaks of EuLCOOH broadened because of amorphous-like aggregation. EuLCOOH retains the ff emission of Eu in a wide pH range of 2.6-9.7 and shows spectral reversibility at pH = 1.9-11.9. From Horrocks' equation, the number of coordinated water molecules to Eu of EuLCOOH in the initial condition (3.0 x 10(-5) mol cm(-3); pH 2.6-9.7) was estimated to be 1, but it increased in both strongly alkaline and acidic solutions. Molecular structural changes in these solutions were assumed from the quantum yields and electrospray ionization-mass spectrometry measurements. For instance, one carboxyl group of EuLCOOH could provide hydrophilicity in the initial condition, and the other would be released from Eu at pH 2.1-2.6. Furthermore, EuLCOOH decomposes below pH 1.9, but recovers with adjustments toward the initial pH. The ff emission of TbLCOOH with a coordinated water molecule also appears in the green wavelength region in the initial condition. The luminescence ability of TbLCOOH in water is higher than that in its powder. The luminescence processes of these complexes are discussed as an energy relaxation through the excited triplet state of L-COOH assigned from the phosphorescence band of GdLCOOH.

The development of an effective adsorbent for cleansing polluted water is required for environmental purification. In this respect, a supramolecular hydrogel constructed by the self-assembly of small molecules could be a strong candidate. Adsorption experiments of organic dyes were performed using supramolecular hydrogels of amphiphilic tris-urea 1. Cationic organic dyes were adsorbed efficiently; indeed, the adsorption of methylene blue was as high as 4.19 mol equivalents relative to 1. Two luminescence peaks were observed in the rhodamine 6G-adsorbed supramolecular hydrogels, and their ratios varied with the amount of dye adsorbed. Fluorescence microscopy images of the supramolecular hydrogel at lower dye levels exhibited fibrous fluorescence consistent with the fibrous aggregates of 1. According to these results, adsorption may proceed gradually, that is, occurring initially on the fibers and later in the aqueous spaces of the supramolecular hydrogel.

Among atomically thin two-dimensional (2D) materials, molybdenum disulfide (MoS2) is attracting considerable attention because of its direct bandgap in the 2H semiconducting phase. On the other hand, a 1T-metallic phase has been revealed, bringing complementary application. Recently, thanks to top-down fabrication using electron beam (EB) irradiation techniques, in-plane 1T-metal/2H-semiconductor lateral (Schottky) MoS2 junctions were demonstrated, opening a path toward the co-integration of active and passive two-dimensional devices. Here, we report the first transport measurements evidencing the formation of a MoS2 Schottky barrier (SB) junction with barrier height of 0.13-0.18 eV created at the interface between EB-irradiated (1T)/nonirradiated (2H) regions. Our experimental findings, supported by state-of-the-art simulation, reveal unique device fingerprint of SB-based field-effect transistors made from atom-thin 1T layers.

The interfacial reduction of a Eu complex with phenanthroline on SiO2 nanoparticles was elucidated by investigating the surface reaction with various adsorbed solvents. A change in the emission color of Eu ions as a consequence of reduction was successfully induced by a thermally activated reaction with ethanol on the SiO2 surface.

Polymeric chain-structured complexes were prepared with helical lanthanide complexes (LnL; Ln = Eu-III, Tb-III, Gd-III) and benzene-dicarboxylate derivatives (benzene-1,4-dicarboxylate (bdc), 2-aminoterephtalate (atpa) and 2-hydoloxyterephtalate (htpa)), which show some noteworthy physicochemical properties, photoluminescence and thermal stabilities. The complex EuL-bdc shows bright luminescence originating from Eu-III by UV excitation. The emission color can be tuned by mixing with TbL. The structures of these chain complexes were clarified with synchrotron X-ray powder diffraction measurements. The derivation of the linker moiety (bdc, atpa or htpa) was found to affect the intermetal energy transfer from Tb-III to Eu-III.

Hierarchical self-assembly of an amphiphilic tris-urea in aqueous media is shown. A mixture of the amphiphilic tris-urea and an alkaline solution gave a viscous solution composed of fibrous aggregates. This viscous solution transformed into supramolecular hydrogels, which are capable of hierarchically organizing into higher-order aggregates in response to several cationic triggers. The resulting supramolecular hydrogels were relatively stiff and their storage moduli attained over 10(3)Pa. The stimuli-responsive and optical properties of the resulting hydrogels were influenced by the cationic trigger. Proton and calcium ion triggers gave pH- and chemical stimuli-responsive hydrogels, respectively. A terbium ion trigger also provided a highly luminescent hydrogel through energy transfer from the tris-urea to terbium.

In this study, Eu-coated SiO2 nanoparticles have been prepared, consisting of an interfacial complex of Eu and 1,10-phenanthroline (phen) at the solid surfaces of the SiO2/Eu nanostructures. The asprepared SiO2/Eu/phen nanoparticles exhibits sharp red emission via energy transfer from the phen to the EuIII. After sintering at 200 degrees C in air, the emission is tuned from red to blue. The blue emission is originated from EuII. This reduction-induced emissive phenomenon resulted from the electron-donating environment created by the surrounding phen and SiO2, which is the first reported fabrication of a stable EuII-based emissive material using mild conditions (reaction in air and at low temperature) and an organic-inorganic hybrid nanostructure. The existence of two different stable oxidation states with characteristic emissions, blue emissive EuII and red emissive EuIII, suggests significant potential applications as novel luminescent materials with inorganic-organic hybrid structures.

Luminescence mechanisms of Eu-III, Tb-III, Gd-III and Nd-III complexes with a hexadentate ligand (abbreviated to EuL, TbL, GdL, and NdL, respectively), which have two bipyridine moieties bridged by an ethylenediamine unit, have been examined. Our molecular design is that each complex forms a single helical polar structure based on the chelate ring to retain solubility in solutions. EuL and NdL show comparably bright emission from ff transitions both in acetonitrile solution and in the solid state. To understand the mechanism of the emission in detail, the energy level of the triplet (T) state of the ligand L has been estimated based on the phosphorescence measurements of GdL, because Gd-III shows no ff emission. The donor level of the T state of L and the acceptor level of Eu-III or Nd-III can overlap, indicating that the excited photon localized on L has been used for the efficient ff emission, while not for pi pi* emission. For TbL, the luminescence quantum yield is significantly dependent on temperature and the state: in the solid state of TbL, the quantum yield of ff emission is over 90% at 77 K, while no luminescence is observed at room temperature, and in solution TbL shows no emission. This observation suggests that the emissive f-level of Tb-III and the energy donor level of the excited T state of L are in thermal equilibrium. The described lanthanide complexes are stable and retain their molecular structure even in solutions and show characteristic luminescence behaviour based on the energy relaxation process of each lanthanide ion. Furthermore the Ho-III complex with L (HoL) has been prepared and its structure has been analyzed. HoL has a twisted arrangement of the bipyridine moiety surrounding Ho-III due to the small ionic radius of Ho-III.

A thin solid-state dye-sensitized photovoltaic cell is fabricated by composing organic and inorganic heterojunctions in which the visible-light sensitizers are cyclopentadiene derivatives (Cp*) coordinated to a metal oxide, typically TiO2. The coordination bonds of the metallocene molecular complex (Ti-Cp*) create a new LMCT (ligand-to-metal charge transfer) absorption band and induce a rectified charge transfer from the organic ligands to TiO2, leading to photocurrent generation. Photovoltaic junctions are completed by coating crystalline organic molecules (perylene) as a hole-transport layer on the Cp*-coordinated TiO2 surface by using the vapor deposition method. The molecular plane of Cp* on the TiO2 surfaces seems to help the hole-transport layer to form ordered structures, which effectively improve carrier conductivities and minimize interfacial resistance. The organic-inorganic hybrid thin-film photocell with metallocene molecular complexes is capable of generating high open-circuit voltages exceeding 1.2 V.

A frilly crystalline heterojunction of organo-metal-halide perovskite, CH3NH3PbI3_ Clx (X &lt; 0.24), and perylene constitutes a planar photovoltaic cell that yields a photovoltage exceeding 1.2 V with a single junction cell absorbing up to 800 nm. Here, perylene not only works as a hole conductor but also contributes to photovoltage as a photoconductor. The crystalline plane orientation of perovskite prepared on TiO2 was controlled by thermal annealing such that the lead halide (110) plane that participates in carrier conduction is highly oriented to enhance the photovoltaic performance The crystal orientation improves the heterojunction structure with perylene. For the best cell with high crystalline orientation, a total voltage loss is significantly minimized to 0.32 V with respect to the absorption band gap of 1.55 eV. The planar crystal cells generate high open-circuit voltages of 1.15-1.22 V, which is close to a theoretical maximal voltage (1.25-1.3 V) described by the Shockley-Queisser efficiency limit. The cell yielded energy conversion efficiency up to 4.96%. 0 2014 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.

A thin solid-state photovoltaic cell of organic-inorganic hetero junctions was fabricated by forming a dye-metal charge-transfer complex as the sensitizer monolayer at the interface of crystalline state organic and inorganic semiconductors. The organic-inorganic hybrid thin-film photocell generates a high photovoltage of 1.2 V, yielding an energy conversion efficiency of up to 1.5%.

A Eu-III cryptate complex constructed from a Cu-II cryptand with an L-tBu ligand, [(EuCu2II)-Cu-III(L-tBu)(2)(NO3)(3) (MeOH)], and the corresponding Ca-II and Na-I cryptates, [(CaCu2II)-Cu-II(L-tBu)(2)(NO3)(2)(MeOH)(2)] and[(NaCu2II)-Cu-I(L-tBu)(2)(Me2CO)] (BPh4), have been synthesized and characterized in order to shed light on the essential role of Cu-II in the luminescence of a Eu-III cryptate. The unprecedented role of a Cu-II cryptand makes it possible to produce lanthanide luminescence in a Eu-III cryptate complex and is successfully elucidated by comparison with the corresponding Ca-II and Na-I cryptates.

In the model system [Ln(phen/phen-d(8))(2)(NO3)(3)] (Ln = Eu3+, Tb3+) the assignment of a new modification, based on the unit cell volumes, demonstrates the superior angular accuracy of synchrotron powder diffraction and the value of the lattice parameters refined thereof.

The structural and spectroscopic properties of a Cu(I) complex bearing a methylene-linked bis(N-heterocyclic carbene) ligand, [Cu-2(mu-Me-mbim)(2)](PF6)(2) were investigated. X-ray single crystal structure analysis revealed that the complex is binuclear similar to the corresponding silver(I) complex. In [Cu-2(mu-Me-mbim)(2)](PF6)(2), cation-p interaction between copper and the adjacent carbene carbon is observed. On the other hand, the copper-copper interaction is very weak in the crystal and almost negligible in solution. The absorption spectrum of [Cu-2(mu-Me-mbim)(2)](PF6)(2) in methanol shows a strong absorption band (epsilon = 23 000 dm(3) mol(-1) cm(-1)) and a weaker shoulder (epsilon = 6200 dm(3) mol(-1) cm(-1)) at 261 nm and 300 nm, respectively. From molecular orbital calculations using TD-DFT, these absorption bands are assigned to the metal-centered transitions with some contribution from the NHC orbitals. The powdered sample of [Cu-2(mu-Me-mbim)(2)](PF6)(2) shows bright blue-green phosphorescence with a high quantum yield (43%). The phosphorescence is of dual-emission character at room temperature with peak maxima at 374 nm and 482 nm whereas it changes to a single emission band centered around 500 nm at 77 K. Molecular orbital calculations indicate that the luminescence derives from the triplet MC and MLCT mixed excited states. A methanolic solution of [Cu-2(mu-Me-mbim)(2)]-(PF6)(2) shows yellow-green phosphorescence with a peak maximum at 542 nm. Unlike in the solid state, no dual-emission was observed. These results suggest that the dual emission is caused by differences in the contribution of metal-metal interactions at room temperature in the solid state. The differences in the absorption and emission properties between [Cu-2(mu-Me-mbim)(2)](PF6)(2) and the related Cu(I)-diphosphine complex, [Cu-2(mu-dcpm)(2)](BF4)(2) are discussed.

A diterbium(III) complex was synthesized by using p-tert-butylsulfonylcalix[4]arene, which adopts a 1,2-alternate conformation, acts as a sensitive optical-antenna chromophore for UV and near-UV light and causes easy-axis magnetic anisotropy in the Tb(III) ions. The complex showed efficient If emission with a corrected quantum yield of ca. 85% even at room temperature. In addition, it showed superparamagnetic behaviour due to slow magnetic relaxation at low temperatures. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

A Novel coordination system with ff-emission of Tb(III) was obtained on a polyvinyl alcohol (PVA) film surface. On this film the ff-emission is polarized, and is intensified by polymer stretching. XAFS spectra show that the mean bond distances between Tb(III) and the nearest neighbour atoms of the 1,10,-phenanthroline ligand on the film are close to those in [Tb(SA)3], Tb(NO(3))(3)H(2)O and [Tb(phen)(2)(NO(3))(3)].

The electronic and structural behaviour of a Pr(III) complex with 4,7-diphenyl-1,10-phenanthroline, [Pr(bathophen),(NO), is investigated with respect to the effect of configuration changes on the Pr(III) centre. [Pr(bathophen)(2)(NO3)(3)] luminesces from the excited states of the ligand and the metal ion. The fluorescence, ff-emission (D-1(2) -&gt; H-3(4)), and phosphorescence bonds appear at 394, 608.2 and 482 nm, respectively, in the solid state. In acetonitrile, the complex also shows multiple emissions. From the time-resolved emission and the lifetime measurements, the excitation energy-transfer in [Pr(bathophen)(2)(NO3)(3)] is clarified, that is, the upper excited triplet level of the ligand acts as on energy donor, while the D-1(2), levels of Pr(III)) is the acceptor. Additionally, the emission phenomena of the complex can be modified by molecular distortion, particularly by rotation of the phenyl groups in the ligand.

A novel emissive molecular system is constructed by the intercalation of the. fluorophore melem (triamino-tri-s-triazine) within a Langmuir-Blodgett (LB). film of stearic acid with the periodic arrangement of lanthanides (Ln(III)), mainly Pr(III) with supporting of Eu(III). From emission spectra, decay curves, quantum yields and XPS measurements, it is clarified that the external heavy metal effect of Pr(III) on melem is much stronger in the film than in the bulk solid state, resulting in producing an unusual triplet state of melem. The triplet state of melem in the LB film donates the excitation energy to Pr(III) in the LB film, which is completely different from the energy transfer pathway of Pr-melem complex in the solid state through the singlet state of melem.

The long-chain alkyl groups of new bidentate ligands make it possible to generate nickel MX-chain complexes exhibiting the shortest Ni-III-Ni-III distance among all MX-chain compounds reported. Dissolution in organic solvents occurs with-out dissociation of the MX-chain units, and the successful fabrication of thin films is reported. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007).

The intramolecular excitation energy transfer from the fluorophore ligand (phens) to Pr(III) in the complexes on the basis of the picosecond time-resolved luminescence spectra is discussed. These complexes exhibit sequentially multiplex emissions from the energy levels on the ligand as (1)pi pi(1)* in the UV region, and from those on Pr(III) as ff in the visible region. From the decay curve analysis of these emissions, the intramolecular energy transfer pathway was clarified quantitatively following the spin-selection rule. The rate constants of energy transfer from the ligand to Pr(III) were estimated, from the (1)pi pi(1)* of phen to the I-1(6) state of Pr(III) via the triplet state. This mechanism can be applied to control the emission properties of Pr(III) complexes by changing the emissive f-levels due to ligand variations. (c) 2005 Published by Elsevier B.V.

Melamine or melem forms a coordination compound with Pr(III). From detailed measurements of electronic absorption and luminescence spectra reported here, it can be concluded that the excitation energy transfer of the Pr(III)-melamine complex occurs via an electron exchange mechanism, whereas the Pr(III)-melem follows a Coulomb mechanism. (c) 2006 Elsevier Ltd. All rights reserved.

Dinuclear and cubane-shaped lanthanide cluster complexes containing Eu-III and Tb-III were synthesized by step-by-step construction using p-tert-butylsulfonylcalix[4]arene as a cluster-forming ligand. The sulfonylcalixarene adopts a pinched-cone conformation in the dinuclear complexes and a cone conformation in the cubane complexes. Because the calixarene has a large pi-conjugate system expanding over the entire molecule, it behaves as a good antenna chromophore for UV and near-UV light, and a slight conformational change of the calixarene ( from cone to pinched-cone and vice versa) has an effect on the energy levels of excited S-1 and T-1 states. As a result, selectivity is observed in the luminescent properties of dinuclear and cubane-shaped systems of Eu-III and Tb-III.

From the measurement of the picosecond time-resolved luminescence spectra of a Pr(III) complex with phenanthroline in the solid state, an intramolecular energy-transfer mechanism from the ligand to the center metal has been discussed. The rate constant of the energy transfer can be estimated as 3.3 x 10(9) s(-1), and it is necessary the excited triplet state of the ligand and a singlet of the metal ion to pass the energy transfer.