Structure and properties of electrodeposited films and film stacks for precursors of chalcopyrite and kesterite solar cells

A comparative analysis of the structure and surface morphology of copper, indium, tin, and zinc films and their layered compositions fabricated by electrochemical deposition in the galvanostatic steady-state mode, galvanostatic mode with the ultrasonic agitation of electrolytes, and forward and reverse pulsed modes with rectangular potential pulses is made. The effect of the electrodeposition modes on the structure, optical properties, and surface morphology of amorphous and crystalline selenium films is studied. Cu/In/Se and Cu/Sn/Zn/Se film compositions, which are model precursors of, respectively, chalcopyrite CuInSe₂ and kesterite, are fabricated by successive electrochemical deposition. Upon being converted by subsequent annealings to CuInSe₂ and Cu₂ZnSnSe₄ semiconductor materials, these precursors will be used as the base layers for a new generation of inexpensive high-efficiency thin-film solar cells.     

The influence of prolonged storage and forward-polarity voltage on the efficiency of CdS/CdTe-based film solar cells

The influence of storage for 48 months and subsequent effect of the forward-polarity voltage on the operational efficiency of film solar cells with the starting layered structure n ⁺-ITO/n-CdS/p-CdTe/Cu/Au is investigated by the methods of the current-voltage and capacitance-voltage characteristics. A physical model of degradation of this type of solar cells under the influence of the mentioned factors is improved based on the obtained results. The conditions are determined under which partial efficiency restoration of these cells after their degradation is possible via holding at room temperature under a forward bias voltage of the p-n heterojunction lower that the open-circuit voltage.     

Effect of interfacial reactions on the photoelectric performance of In/CdTe/ITO and CrOxCdTe/ITO heterostructures

By evaporating undoped CdTe layers onto indium tin oxide (ITO), followed by a layer of In or CrO_x, back-effect photovoltaic cells In/CdTe/ITO and CrO_x/CdTe/ITO were prepared. It was shown that reducing the area of grain boundaries in CdTe, bringing the space-charge region farther away from the defect-rich region at the CdTe/ITO interface, and employing CrO_x instead of In back contacts raise the quantum efficiency of the devices to 6%.     

Structure and properties of nanostructured ZnO arrays and ZnO/Ag nanocomposites fabricated by pulsed electrodeposition

We investigate the structure, surface morphology, and optical properties of nanostructured ZnO arrays fabricated by pulsed electrodeposition, Ag nanoparticles precipitated from colloidal solutions, and a ZnO/Ag nanocomposite based on them. The electronic and electrical parameters of the ZnO arrays and ZnO/Ag nanocomposites are analyzed by studying the I–V and C–V characteristics. Optimal modes for fabricating the ZnO/Ag heterostructures with the high stability and sensitivity to ultraviolet radiation as promising materials for use in photodetectors, gas sensors, and photocatalysts are determined.     

Electrodeposited zinc oxide arrays with the moth-eye effect

The materials of modern photovoltaic cells exhibit significant light reflection which is avoided using antireflective coatings. The possibility of fabricating antireflective coatings such as nanoscale zinc oxide arrays with a parabolic profile by pulsed electrochemical deposition from aqueous electrolytes is shown for the first time. The effect of the deposition conditions on the optical properties of oxide arrays is studied using spectrophotometry. The structural characteristics are analyzed by X-ray diffraction data. The morphology of the grown arrays is determined by atomic-force microscopy. Optimization of the pulsed electrodeposition conditions allows correction of the parabolic nanonipple sizes, thus providing the fabrication of antireflective coatings based on electrodeposited zinc oxide arrays with the moth-eye effect, applicable to photovoltaic cells.     

Confined Catalytic Janus Swimmers in a Crowded Channel: Geometry‐Driven Rectification Transients and Directional Locking

Self‐propelled Janus particles, acting as microscopic vehicles, have the potential to perform complex tasks on a microscopic scale, suitable, e.g., for environmental applications, on‐chip chemical information processing, or in vivo drug delivery. Development of these smart nanodevices requires a better understanding of how synthetic swimmers move in crowded and confined environments that mimic actual biosystems, e.g., network of blood vessels. Here, the dynamics of self‐propelled Janus particles interacting with catalytically passive silica beads in a narrow channel is studied both experimentally and through numerical simulations. Upon varying the area density of the silica beads and the width of the channel, active transport reveals a number of intriguing properties, which range from distinct bulk and boundary‐free diffusivity at low densities, to directional “locking” and channel “unclogging” at higher densities, whereby a Janus swimmer is capable of transporting large clusters of passive particles.     

On Controlling the Hydrophobicity of Nanostructured Zinc-Oxide Layers Grown by Pulsed Electrodeposition

The possibility of fabricating highly hydrophobic nanostructured zinc-oxide layers by the inexpensive method of pulsed electrodeposition from aqueous solutions without water-repellent coatings, adapted for large-scale production, is shown. The conditions of the deposition of highly hydrophobic nanostructured zinc-oxide layers exhibiting the “rose-petal” effect with specific morphology, optical properties, crystal structure and texture are determined. The grown ZnO nanostructures are promising for micro- and nanoelectronics as an adaptive material able to reversibly transform to the hydrophilic state upon exposure to ultraviolet radiation.