We suggest a photoelectrochemical detector based on semiconductor bismuth thioiodide BiSI with the band gap energy Eg = 1.59 eV (direct optical transitions). The bismuth thioiodide was synthesized by the chemical bath deposition on a conductive FTO glass. The structure of BiSI film represents randomly oriented needle-like single crystals. The nucleation and growth of needle-like BiSI single crystals from a single center and the absence of inter-crystallite boundaries provide a high external quantum efficiency of photocurrent up to 52 % at 400 nm. It corresponds to ampere-watt responsivity of 0.16 A/W. BiSI photodetector possesses a high specific detectivity of 3.4 center dot 1011 cm center dot Hz1/2/W and an on/off time equal to 26/435 ms. In aqueous electrolyte containing both S2-and Ianions, the photodetector is characterized by a high temporal stability of photocurrent and cyclability (thousands of cycles) under visible light illumination.

Cu2O films were electrochemically deposited on FTO glasses, and the simplest solid-state structures were prepared by the formation of silver contact on the surface of Cu2O film. Addition of europium nitrate to the electrodeposition electrolyte results in a few time increase of the responsivity of FTO/Cu2O/Ag structures both in the photodiode (without application of an external bias voltage) and photoresistor (with an external bias voltage) operation modes. In particular, in the self-powered mode, the photodetector prepared with the addition of Eu(III) to the electrolyte demonstrates 4-fold increase in the ampere-watt responsivity reaching 6.7 mA/W at 589 nm. At an external bias of 2 V, the ampere-watt responsivity and specific detectivity under 525 nm illumination for the Eu-modified film-based photodetector are 87.2 A/W (18-fold increase) and 3.11∙1012 cm∙Hz0.5/W (6-fold increase), respectively. The increase in photosensitivity is explained by the suppression of charge carrier recombination in the films prepared with the addition of europium, which is confirmed by the photoluminescence spectroscopy.

Herein, we investigate the phase evolution and reactions of vanadium hexacyanoferrate (VHCF) cathode in aqueous Zn-ion battery. X-ray diffraction, in situ Raman spectroscopy, scanning electron microscopy, time-offlight secondary-ion mass spectrometry, and electrochemical methods reveal electrochemical activation of VHCF electrode in multiple charge-discharge cycles that eventually converts VHCF into zinc hexacyanoferrate and vanadium oxides (VOx). The emerging VOx redox behavior enhances the specific capacity of the electrode from 77 to 165 mAh g-1. Operando UV-vis absorption spectra of the electrolyte in the vicinity of the electrode during electrochemical reaction verifies the presence of decavanadate anion - the intermediate of VHCF transformation into the electrochemically active vanadium oxide. Analysis of the electrodes under various electrochemical conditions and experiments in aqueous and non-aqueous media demonstrate that vanadium of VHCF is redox inactive in the pristine material but products of VHCF transformation start to contribute to the specific capacity of the electrode upon the formation of vanadium oxide.

Bismuth oxysulfide (BOS) films were formed on dielectric glass substrates by the chemical bath deposition. They have a high sensitivity to moisture content and demonstrate the decrease in the electrical resistance up to three orders of magnitude when the relative humidity reaches 85% and more. The high sensitivity of resistive structure representing 0.65 & mu;m thick film between two Ag contacts is associated with randomly oriented thin nanoplate crystals. The presence of a great number of intergrain boundaries restricts electron transport (both in the dark and under illumination), which is desirable for resistive humidity sensors. The BOS films possess a high surface-to-volume ratio making them ultra-sensitive to adsorption of water. It is supposed that ionic conductivity in a thin layer of adsorbed water plays a crucial role in fast response of sensing structure (1-3 s) to adsorption-desorption cycles. High dark resistance and low photoconductivity of BOS films make them practically insensitive to processes of molecular oxygen adsorption and action of light when they are used as humidity sensing structure.

Strong room temperature exciton photoluminescence (PL) has been observed in copper (I) oxide films electrochemically deposited in a tartrate electrolyte. The PL intensity of these films is two orders of magnitude higher than that of films deposited from the classical lactate electrolyte. X-ray diffraction (XRD) and Raman spectroscopy analyses demonstrate that the films prepared using tartrate electrolyte are characterized by higher grain size, which reduces a non-radiative recombination of charge carriers. Better optical quality of the Cu2O films prepared using tartrate electrolyte is explained taking into account stronger tartrate-copper complexes, which results in lower density of grain boundaries in such films. Moreover, higher buffering capacity of the tartrate complex provides stability of pH value in the diffusion layer of the near-electrode space preventing defect formation. Our study demonstrates the promise of using Cu2O films deposited from tartrate solution for solar energy applications like photoelectric energy conversion, hydrogen production, and photocatalysis.

In this work, different MnO2 polymorphs are applied as cathodes in zinc-ion batteries (ZIBs). All the polymorphs result in similar electrochemical behavior in weak acidic (1 М) ZnSO4 aqueous solutions at comparable specific capacity (200–225 mAh g−1), similar charge–discharge curves, and temporal stability owing to an irreversible modification of the pristine positive electrode during battery charge and discharge. This irreversibility stems from the dissolution and re-deposition of MnO2 and the formation of new manganese and zinc compounds (basic salt deposits such as ZnMn2O4, Mn2O3, and MnOOH). The additional (new) MnO2 phase is formed via two routes: disproportionation of Mn+3 ions formed during the discharge process and anodic oxidation of Mn2+ ions in a solution. According to X-ray diffraction and Raman spectroscopy analyses, the re-deposited MnO2 is in an amorphous state. The amorphous MnO2 covers the surface of the initial crystalline particles and affects the electrochemical behavior of the ZIBs. The strong pH dependence of the electrochemical response of the MnO2 electrodes is related to the H+ concentration effect on ionic equilibria in this system, such as the formation of basic zinc and manganese salts and hydroxides as well as the disproportionation of Mn+3 and anodic oxidation of Mn+2.

Strong photoluminescence (PL) of ND1 radiation center with zero-phonon line (ZPL) at 393.5 nm has been excited in irradiated diamonds with a laser working at a wavelength of 355 nm. Emission of the ND1 center consists of ZPL and vibrational replicas related to quasilocal vibrations of an energy 76 meV. PL and absorption spectra of ND1 center exhibit very close mirror symmetry. The energies of the quasilocal vibrations are the same in luminescence and absorption. The interaction with the lattice phonons at the ND1 center is very weak. In luminescence of the irradiated diamonds, ND1 center behaves like one related to simple primary radiation defects in negative charge state. PL of the ND1 center is stimulated by nitrogen donors and suppressed by boron acceptors. It is assumed that the luminescence of the ND1 center is effectively excited only in the spectral range of its intrinsic absorption from 340 to 390 nm.

A method for studying photosensitive structures using the example of studying the photodegradation and dark recovery of organic-inorganic perovskite solar cells is present. The method is based on the use of a confocal spectrometer to measure Raman spectra, photo- and electroluminescence spectra and kinetics, the kinetics of the short-circuit current and the open-circuit voltage under local exposure to monochromatic radiation. Raman spectra make it possible to establish the presence or absence of secondary phases, the formation of which is possible in photosensitive layers under the influence of light. The photoluminescence spectra enable to reveal the single-phase nature of the object under study. Mapping the intensity and position of the center of mass of the photoluminescence band in the plane of the object makes it possible to judge the spatial arrangement of the centers of non-radiative recombination of charge carriers, the distribution of the regions with the highest and lowest efficiency of the extraction of charge carriers by transport-acceptor layers and the spatial homogeneity of the chemical composition. Comparison of the electroluminescence spectra before and after light exposure allows revealing the formation of non-radiative recombination centers in the photoabsorbing layer and at interfaces with the transport layers. Analysis of the kinetics of changes in the parameters of the photoluminescence band obtained by measuring the short-circuit current and the open-circuit voltage makes it possible to establish the dominant photoinduced processes leading to a change in the intensity of the photoluminescence band.

Selective electrochemical transformations of bismuth interlayers in (Bi2)m(Bi2Te3)n superlattices can be of interest as a means of thermoelectric materials design based on bismuth telluride. In this work, the interlayers in the electrodeposited (Bi2)m(Bi2Te3)n superlattice structures formed by pulse potential controlled electrodeposition were characterized with electrochemical microgravimetry on quartz crystal electrodes, cyclic voltammetry, potentiodynamic electrochemical impedance spectroscopy (PDEIS), and in situ Raman spectroscopy. The oxidation potential of bismuth in the interlayers is in between the potentials of metallic bismuth and bismuth telluride anodic oxidation, which allows electrochemical detection and selective anodic dissolution of the interlayer bismuth. Microgravimetry and cyclic voltammetry have provided monitoring of bismuth interlayer dissolution and the subsequent underpotential deposition (upd) of bismuth adatoms onto Bi2Te3 layers in the electrochemically created slits. PDEIS provided separate monitoring of the interfacial charge transfer, spatially restricted diffusion, capacitance of faradaic origin, and double-layer capacitance, which disclosed different variations of the electrochemical interface area in the superlattices with initial bismuth content below and above that of Bi4Te3. In situ Raman spectroscopy has monitored the removal of bismuth interlayers and distinguished different locations of Bi adatoms in two stages of Bi upd. The electrochemically created slits of molecular dimension have a potential of being used as sieves, e.g., to provide selective accessibility of the electrochemically created centers inside them to molecules and ions in multi-component solutions.

Selective electrochemical transformations of bismuth interlayers in (Bi 2 ) m (Bi 2 Te 3 ) n superlattices can be of interest as a means of thermoelectric materials design based on bismuth telluride. In this work, the interlayers in the electrodeposited (Bi 2 ) m (Bi 2 Te 3 ) n superlattice structures formed by pulse potential controlled electrodeposition were characterized with electrochemical microgravimetry on quartz crystal electrodes, cyclic voltammetry, potentiodynamic electrochemical impedance spectroscopy (PDEIS), and in situ Raman spectroscopy. The oxidation potential of bismuth in the interlayers is in between the potentials of metallic bismuth and bismuth telluride anodic oxidation, which allows electrochemical detection and selective anodic dissolution of the interlayer bismuth. Microgravimetry and cyclic voltammetry have provided monitoring of bismuth interlayer dissolution and the subsequent underpotential deposition (upd) of bismuth adatoms onto Bi 2 Te 3 layers in the electrochemically created slits. PDEIS provided separate monitoring of the interfacial charge transfer, spatially restricted diffusion, capacitance of faradaic origin, and double-layer capacitance, which disclosed different variations of the electrochemical interface area in the superlattices with initial bismuth content below and above that of Bi 4 Te 3 . In situ Raman spectroscopy has monitored the removal of bismuth interlayers and distinguished different locations of Bi adatoms in two stages of Bi upd. The electrochemically created slits of molecular dimension have a potential of being used as sieves, e.g., to provide selective accessibility of the electrochemically created centers inside them to molecules and ions in multi-component solutions.

The effect of Al2O3 – CuI oxide films on the photoelectric parameters of silicon solar cells (SCs) has been studied. The largest increase in the external quantum efficiency of photoelectric conversion of SCs in the near UV range is observed for monolayer films of the 50Al2O3 – 50CuI composition, heat-treated at 280 °C for 30 min, which corresponds to a relative increase in the photocurrent upon exposure to radiation of spectral composition AM1.5 (1000 W/m2 ) by more than 35 %. This confirms the efficiency of using re-emitting Al2O3 – CuI films to increase the efficiency of silicon SCs.

An optical pump–probe technique was used to detect spatial distribution of carrier lifetimes across the thickness of a high-quality diamond device structure. Two samples with as-received and boron implanted surfaces were compared to assess the role of implantation and related processing on carrier recombination mechanisms. It was found that the two implanted surfaces show very different behaviors despite undergoing the same treatment. At one of the surfaces, carrier lifetimes remained relatively unchanged, indicating surface recombination rates in the 102–103 cm/s range. At the other surface, carrier lifetimes were almost a magnitude lower and correlated with the locally detected nitrogen vacancy defect that was attributed to the elevated concentration of residual nitrogen.

Herein, the promising properties of open‐structured NaV3O8 as a cathode material for Zn‐ion batteries (ZIBs) are investigated. First‐principles calculations predict the insertion of Zn2+ (0.74 Å) in NaV3O8 with an interlayer distance of ≈7 Å, enabling delivery of a high discharge capacity of 353 mAh g−1 at 70 mA g−1 (0.2 C) for 300 cycles in the operating window of 0.3−1.5 V in 1 m Zn(CF3SO3)2 aqueous solution. Operando synchrotron X‐ray diffraction, X‐ray absorption near edge structure spectroscopy, and first‐principles calculations validate the insertion of Zn2+ into the NaV3O8 structure within the operation range. Moreover, operando synchrotron X‐ray diffraction and operando Raman spectroscopy reveal the formation of layered zinc hydroxytriflate (Zn5(OH)8(CF3SO3)2∙xH2O) as a side reaction below 0.8 V on discharge (reduction) and its dissolution into the electrolyte above 0.8 V on charge (oxidation). The formation of the Zn hydroxytriflate interfacial layer increases the charge‐transfer activation energy from 15.5 to 48 kJ mol−1, leading to kinetics fade below 0.8 V. The findings reveal the charge‐storage mechanism for NaV3O8, which may also be applicable to other vanadate cathodes, providing new insights for the investigation and design of ZIBs.

Carrier-transport mechanisms are studied in high-purity diamond irradiated with 6 MeV electrons in the dose range of 1012–1016 cm−2 and annealed at different temperatures up to 1450 °C. Lifetimes and diffusion coefficients are extracted using two pump–probe techniques based on free-carrier absorption and transient-grating principles and then correlated with the corresponding defect evolution from spectroscopic measurements. The neutral monovacancy is revealed as the main carrier recombination center in the as-irradiated diamond, providing bipolar carrier lifetimes of a few nanoseconds at the highest irradiation dose. Carrier-capture cross sections are reduced during annealing as vacancies aggregate into divacancies at ≤1000 °C and extended vacancy clusters at 1450 °C.

Numerical simulations of current–voltage curves in electron-only devices are used to discuss the influence of charged defects on the information derived from fitting space-charge-limited current models to the data. Charged, acceptor-like defects lead to barriers impeding the flow of electrons in electron-only devices and therefore lead to a reduced current that is similar to the situation where the device has a built-in voltage. This reduced current will lead to an underestimation of the mobilities and an overestimation of characteristic tail slopes if analytical equations are used to analyze the data. Correcting for the barrier created by the charged defects can, however, be a successful way to still be able to obtain reasonably accurate mobility values. Introduction A frequently used method to analyze charge carrier transport in organic semiconductors is based on space-charge-limited current measurements performed on single carrier devices [1-14]. These devices consist of two contacts that are either both electron-injecting or both hole-injecting, meaning that the current–voltage curve of these devices is not determined by the recombination of electrons and holes in the volume of the device [15] but instead by the mobility and concentration of carriers and the electric field in the device. If a device with two electron injecting contacts were doped to be sufficiently n-type that the electron concentration were determined by the doping and not by the injected charges in a certain range of voltages, the current–voltage curve in that range would be essentially ohmic, and the conductivity of the system would depend on mobility and electron concentration [16,17]. If the electron-only device were, however, undoped and the injection at the contacts efficient, the current density J would to a first approximation not depend on the equilibrium electron concentration anymore. Instead J would just depend on the mobility μ, which is typically the only unknown parameter, as well as the voltage V, the device thickness d and the permittivity ε = ε0εr and would ideally follow the Mott–Gurney law [18,19] Beilstein J. Nanotechnol. 2013, 4, 180–188.

Dense and mesoporous titanium dioxide films have been obtained on titanium substrate by means of thermal oxidation, hydrolysis of polybutyltitanate, deposition of titanium dioxide sol, ultrasonic treatment and anodic oxidation and characterized by scanning electron microscopy, transmission electron microscopy and Raman spectroscopy. Electrochemical activity of titanium dioxide films, initial and modified by gold nanoparticles, in oxygen reduction reaction (ORR) in alkaline medium has been studied by cyclic voltammetry. It has been demonstrated that the efficiency of the dense and mesoporous titanium dioxide films in ORR is determined by their morphology, structure and pore ordering degree. Modification of titanium dioxide films by gold nanoparticles results in the decrease in overpotential of the ORR. It has been found that the electrodes consisted of highly ordered layers of titania nanotubes with deposited gold nanoparticles demonstrate sufficiently higher electrocatalytic activity toward the oxygen electroreduction in comparison with TiO2/Au systems based on dense films and mesoporous films with disordered pore structure. Features of electrochemical behavior of TiO2/Au (nanotubes/nanoparticles) system are explained by the peculiarities of electron transport to the electrode surface and structure of space charge layer in the mesoporous oxide film.

Nanostructured n-Bi2O3/p-CuBi2O4/p-CuO photocathodes with incident photon-to-current conversion efficiency IPCEmax = 70% (λ = 400 nm) have been prepared using electrochemical and chemical methods. Platelet-like BiOI nanocrystals electrochemically deposited on FTO substrate were used as precursors. CuI nanoparticles were deposited on the BiOI surface by successive ionic layer adsorption and reaction technique. Oxidative heat treatment of BiOI/CuI heterostructure in air leads to the formation of the Bi2O3/CuBi2O4/CuO composite. Binary oxide was formed as a result of solid-state interaction between bismuth and copper oxides at their interface. Spectral sensitization of wide-gap n-Bi2O3 (band gap Eg = 2.80 eV) with narrow-gap p-CuBi2O4 (Eg = 1.80 eV) and p-CuO (Eg = 1.45 eV) extends spectral sensitivity range up to 800 nm by Z-scheme implementation: cathodic photocurrent is associated with the transition of photoelectrons from p-CuBi2O4 and p-CuO to the solution, while photoholes recombine with electrons of n-Bi2O3 conduction band. High quantum efficiency of photocurrent was achieved due to band-edge correlation in a three-component oxide heterostructure, combined with an internal electric field in p-CuBi2O4 and effective photon absorption by two narrow-band-gap p-CuBi2O4 and p-CuO semiconductors.

The operational stability of perovskite solar cells (PSCs) remains a limiting factor in their commercial implementation. We studied the long-term outdoor stability of ITO/SnO2/Cs0.05((CH3NH3)0.15(CH-(NH2)2)0.85)0.95PbI2.55Br0.45/spiro-OMeTAD/Au cells, as well as the dynamics of their degradation, under simulated sunlight indoors and their recovery in the dark. The extent of overall degradation was found to depend on processes occurring both under illumination and in the dark, i.e., during the daytime and nighttime, with the dynamics varying with cell aging. Full recovery of efficiency in the dark was observed for cells at early degradation stages. Further cell degradation resulted in recovery times much longer than one night, appearing as irreversible degradation under real operational conditions. At later degradation stages, very different dynamics were observed: short-circuit current density and fill factor exhibited a pronounced drop upon light turn-off but strong improvement under subsequent illumination. The interplay of reversible and irreversible degradation processes with different recovery dynamics was demonstrated to result in changes in the cell’s diurnal PCE dependence during its operational lifespan under real sunlight conditions.

A rapid progress in the development of solar cells based on hybrid organic-inorganic perovskites CH3NH3PbI3 (MAPbI(3)) is observed in recent years, and power conversion efficiency as high as 22.1 % has been reported. However, a low stability is the main drawback of these materials, which impedes their practical use for solar energy conversion. This work is devoted to the synthesis of CH3NH3PbI3 films from CH3NH3I and PbI2 precursors and spectroscopic investigation of their stability under high-intensity laser illumination.

Исследованы обработанные парами пиридина пленки органо-неорганических перовскитов составов CH3NH3PbI3 и CH3NH3Pb(I0,57Cl0,43)3. Анализ измеренных спектров пропускания, фотолюминесценции, а также кинетик интенсивности и центра масс полосы фотолюминесценции в процессе непрерывного освещения показал, что влияние пиридина на органо-неорганические перовскиты неоднозначно: наряду с фотостабилизацией (уменьшением скорости изменения параметров полосы фотолюминесценции при освещении) возникает нежелательный эффект, проявляющийся в резком снижении темновой стабильности (изменении фазового состава в процессе хранения).