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Today, silicon solar cells (amorphous films and wafer-based) are a main source of green energy. These cells and their components are produced by employing various technologies. Unfortunately, during the production process, chemicals that are harmful for the environment and for human life are used. For example, hydrofluoric acid is used to texture the top electrode to improve light harvesting. In this work, and also in recent ones, we report a way to obtain 3D textures on the top electrode by using zinc oxide nanorods. The efficiency of a textured solar cell structure is compared with the one obtained for a planar zinc oxide/silicon structure. The present results show the possibility to produce efficient solar cells on a relatively thin 50 μm thick silicon substrate. Solar cells with structured top electrodes were examined by numerous measuring techniques. Scanning electron microscopy revealed a grain-like morphology of the magnesium-doped zinc oxide film. The size of the grains is closely related to the structure of the nanorods. The external quantum efficiency of the cells was measured. The obtained solar cell shows response in a wide spectral range from ultraviolet to infrared. Current–voltage and current–voltage–temperature measurements were performed to evaluate basic photovoltaic parameters. At room temperature, the cells efficiency equals to 9.1% for textured structures and 5.4% for planar structures, respectively. The work, therefore, describes an environmentally friendly technology for PV architecture with surface textures increasing the efficiency of PV cells.

In order to effectively utilize the photovoltaic properties of gallium arsenide, its surface/interface needs to be properly prepared. In the experiments described here we examined eight different paths of GaAs surface treatment (cleaning, etching, passivation) which resulted in different external quantum efficiency (EQE) values of the tested photovoltaic (PV) cells. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) examinations were conducted to obtain structural details of the devices. X-ray photoelectron spectroscopy (XPS) with depth profiling was used to examine interface structure and changes in the elemental content and chemical bonds. The photoluminescence (PL) properties and bandgap measurements of the deposited layers were also reported. The highest EQE value was obtained for the samples initially etched with a citric acid-based etchant and, in the last preparation step, either passivated with ammonium sulfide aqueous solution or treated with ammonium hydroxide solution with no final passivation. Subsequent I–V measurements, however, confirmed that from these samples, only the sulfur-passivated ones provided the highest current density. The tested devices were fabricated by using the ALD method.

Aleksandra Seweryn,1 Ariadna Pielok,2 Krystyna Lawniczak-Jablonska,1 Rafal Pietruszka,1 Klaudia Marcinkowska,2 Mateusz Sikora,2 Bartlomiej S Witkowski,1 Marek Godlewski,1 Krzysztof Marycz,2,3 Agnieszka Smieszek2 1Institute of Physics, Polish Academy of Sciences, Warsaw PL-02668, Poland; 2Wroclaw University of Environmental and Life Sciences, Department of Experimental Biology, Wroclaw PL-50375, Poland; 3Cardinal Stefan Wyszynski University, Collegium Medicum, Warsaw PL-01938, PolandCorrespondence: Aleksandra SewerynPolish Academy of Sciences, Aleja Lotnikow 32/46, Warsaw PL-02668, PolandTel +48 22 116 33 99Fax +48 22 843 09 26Email aseweryn@ifpan.edu.plAgnieszka SmieszekWroclaw University of Environmental and Life Sciences, Norwida St. 27 B, Wroclaw PL-50-375, PolandTel +48 71 320 5229Fax +48 22 843 09 26Email agnieszka.smieszek@upwr.edu.plIntroduction: The development of the field of biomaterials engineering is rapid. Various bioactive coatings are created to improve the biocompatibility of substrates used for bone regeneration, which includes formulation of thin zirconia coatings with pro-osteogenic properties. The aim of this study was to assess the biological properties of ZrO2 thin films grown by Atomic Layer Deposition (ALD) technology (ZrO2ALD).Methodology: The cytocompatibility of the obtained layers was analysed using the mice pre-osteoblastic cell line (MC3T3) characterized by decreased expression of microRNA 21-5p (miR-21-5p) in order to evaluate the potential pro-osteogenic properties of the coatings. The in vitro experiments were designed to determine the effect of ZrO2ALD coatings on cell morphology (confocal microscope), proliferative activity (cell cycle analysis) and metabolism, reflected by mitochondrial membrane potential (cytometric-based measurement). Additionally, the influence of layers on the expression of genes associated with cell survival and osteogenesis was studied using RT-qPCR. The following genes were investigated: B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax), p53 and p21, as well as osteogenic markers, i.e. collagen type 1 (Coll-1), osteopontin (Opn), osteocalcin (Ocl) and runt-related transcription factor 2 (Runx-2). The levels of microRNA (miRNA/miR) involved in the regulation of osteogenic genes were determined, including miR-7, miR-21, miR-124 and miR-223.Results: The analysis revealed that the obtained coatings are cytocompatible and may increase the metabolism of pre-osteoblast, which was correlated with increased mitochondrial membrane potential and extensive development of the mitochondrial network. The obtained coatings affected the viability and proliferative status of cells, reducing the population of actively dividing cells. However, in cultures propagated on ZrO2ALD coatings, the up-regulation of genes essential for bone metabolism was noted.Discussion: The data obtained indicate that ZrO2 coatings created using the ALD method may have pro-osteogenic properties and may improve the metabolism of bone precursor cells. Given the above, further development of ZrO2ALD layers is essential in terms of their potential clinical application in bone regenerative medicine.Keywords: ALD, zirconia-based coatings, pro-osteogenic properties, cytocompatibility, osteoblasts precursors

A near 1-keV photons from the Xe/He plasma produced by the interaction of laser beam with a double stream gas puff target were employed for studies of L absorption edges of period 4 transitional metals with atomic number Z from 26 to 30. The dual-channel, compact NEXAFS system was employed for the acquisition of the absorption spectra. L1–3 absorption edges of the samples were identified in transmission mode using broadband emission from the Xe/He plasma to show the applicability of such source and measurement system to the NEXAFS studies of the transition metals, including magnetic materials.

One of the important research directions in the field of photovoltaics is integration with construction. The integration of solar cell systems with a building can reduce installation costs and help optimize the used space. Among the few literature reports on photovoltaic roof tiles, solutions with silicon and thin film solar cells dominate. An interesting solution may be the application of dye-sensitized solar cells. In addition to their interesting properties, they also have aesthetic value. In the classic arrangement, they are constructed using glass with a transparent conductive layer (TCL). This article describes replacing a classic glass counter electrode with an electrode based on a ceramic tile and nickel foil. First, a continuous and homogeneous fluorine-doped tin oxide (FTO) thin film was developed so that the above-mentioned substrate could be applied. The atomization method was used for this purpose. Then, nanocolloidal platinum paste was deposited as a catalytic material using the screen printing method. The electrical parameters of the manufactured DSSCs with and without a counter electrode tile were characterized by measuring their current–voltage characteristics under standard AM 1.5 radiation. A dye-sensitized solar cell integrated with ceramic tiles and nickel foil was produced and displayed an efficiency of over 4%. This solution makes it possible to expand their construction applications. The advantage of this solution is full integration with construction, while simultaneously generating electricity. A dye-sensitized solar cell was built layer-by-layer on a ceramic tile and nickel foil.

ZnO nanorods (NRs) were synthesized by the hydrothermal method and coated by HfO2 sell layers by using the atomic layer deposition to form ZnO/HfO2 core/shell NRs arrays. XRD showed the hexagonal wurtzite structure of ZnO NRs and tetragonal phase of HfO2. Scanning electron microscope and atomic force microscopy analysis illustrated vertically well-aligned ZnO/HfO2 core/shell NRs structure. Optical property was studied by PL which revealed that the near band-edge emission of the ZnO NRs improved after coating by HfO2 shells. The band gap energy was estimated about 3.51 eV by UV–Vis. For the first time, the measurements of nonlinear optical (NLO) properties of ZnO/HfO2 core/shell NRs structures have been performed by using a continuous-wave (cw) Nd:YAG laser at 532 nm by the Z-scan technique. A negative nonlinear refractive index and a positive absorption coefficient were calculated equal to 8.6 × 10−6 cm2/W and 1.75 cm/W for ZnO/HfO2 core/shell NRs, respectively. A third-order NLO susceptibility of ZnO/HfO2 core/shell NRs was measured of the order of 10−2 esu which is a large value. The results suggest that ZnO/HfO2 core/shell NRs are promising candidates for NLO applications.

Zinc oxide is nowadays widely investigated in many different science areas. In particular, this wide band gap semiconductor is valued due to its possible use in transparent electronics as TCO (Transparent Conductive Oxide) and/or as ARC (Antireflective Coating). In other applications, ZnO can also play active role in light source devices, UV detectors, solar cells, etc. In this experiment we focused on zinc oxide applicability assessment in solar cell devices. ZnO as well as its Al-doped form AZO (Aluminum doped Zinc Oxide) were examined in view of their use both as TCO and the n-type partner for the p-type gallium arsenide (GaAs) substrate, that resulted in creation of the p-n heterojunction-based photovoltaic device. In order to deposit both ZnO as well as AZO layers, the ALD (Atomic Layer Deposition) method was applied.

The thin layers of ZnO and ZnO: Al (Al doped zinc oxide—AZO) were deposited by the atomic deposition layer (ALD) method on silicon and glass substrates. The structures were deposited using diethylzinc (DEZ) and deionized water as zinc and oxygen precursors. A precursor of trimethylaluminum (TMA) was used to introduce the aluminum dopant. The present study of ALD-deposited ZnO and AZO films was motivated by their applications in photovoltaics. We attempted to expose several properties of such films. Structural, optical (including ellipsometric measurements) and electrical investigations were performed. We discussed the relations between samples doped with different Al fractions and their properties.

In the last few years, perovskite-based solar cells have seen rapid improvements of their power conversion efficiencies (PCE) that have already reached silicon cell values. The commercial use of perovskite cell technology remains, however, a challenge due to durability issues. In fact, perovskite films when exposed to moisture and oxygen undergo degradation within a couple of hours or days. In order to address these problems, several strategies have been developed in recent years, including surface passivation and coating. Herein, we analyze and compare two perovskite stability improvement approaches, each aimed at the reduction of the oxygen diffusion, one by adding chlorine to perovskite precursors in order to block iodine vacancy sites, and the other by coating the perovskite layers with protective Al2O3 films using Atomic Layer Deposition (ALD). The study provides an experimental verification of the degradation mechanism linking it to oxygen diffusion into the perovskite films. As shown by X-ray photoelectron spectroscopy (XPS) analysis, the addition of chlorine into the iodine-based perovskite film slows down the oxygen diffusion, while X-ray diffraction (XRD) measurements show improved stability of such iodide perovskite with chlorine addition. Characteristic times for oxygen diffusion into subsurface region as well as for degradation process of film volume are provided and discussed. XRD measurements are also used to show that an additional significant stability improvement can also be achieved when the films are coated with a protective ALD Al2O3 layer.

Currently, the first generation of silicon solar cells is dominating the photovoltaic market. Silicon cells are produced by various methods, which employ either crystalline or multi-crystalline substrates. However, both these manufacturing processes are expensive and potentially harmful to the environment and health. One example of this is that the surface is given its texture in a highly corrosive water solution of nitric and hydrofluoric acid. Additionally, both the diffusion and manufacturing of p-n junction and of metal contacts are associated with very high temperatures. This prompted us in our search for cheaper and more environmental friendly technologies. In this work, we discuss the possibility of producing components of photovoltaic cells by employing atomic layer deposition and hydrothermal technologies. This does not require the use of hazardous chemicals and high temperatures. The maximum efficiency of zinc oxide/silicon solar cells is 14% and 10% for textured and planar structures, respectively. A environmentally-friendly and simple procedure is thus being proposed, which, together with its relative efficiency, makes it an attractive alternative to the present procedure.

Scratches and constant abrasive wear can result in zinc oxide (ZnO) and aluminum doped zinc oxide (ZnO:Al) layers that render many devices impracticable to use. Currently, the ZnO and ZnO:Al layers are widely used as transparent conductivity oxide (TCO). The top and/or bottom electrodes based on ZnO and ZnO:Al were used in organic light-emitting diodes (OLED), organic and perovskite solar cells in order to replace expensive indium tin oxide (ITO). Consequently, knowledge of the frictional properties of the ZnO layer is a necessity for many scientists. In this study, the tribological properties of zinc oxide that was formed by the Low Temperature Atomic Layer Deposition (LT ALD) method were investigated. ALD-layers (ZnO and ZnO:Al) were deposited on a glass substrates in pre-selected conditions in order to achieve films appropriate for the application of photovoltaics. The results indicate a good adhesion of the films to the substrate. The layers were abraded during friction with Al 2 O 3 ball and their wear intensity depend on hardness of the film/substrate system. The friction coefficient of ZnO film reached value 0.1 and was higher than friction coefficient of ZnO:Al film equal 0.08. The tribological properties of these films are compared with those reported for bulk ZnO and those films deposited by sputtering.

Electric measurements were performed on solar cells composed of n-type ZnO nanorods grown by the hydrothermal method on p-type silicon substrate. The nanorods were covered with silver nanoparticles of sizes 20–30 nm and 50–60 nm. The diameters and density of the nanorods and nanoparticles were determined from scanning electron microscopy (SEM) and atomic force microscopy (AFM) images. On top of the structures the ZnO:Al (AZO) layer was deposited as a transparent electrode using the atomic layer deposition (ALD) method. The efficiency of the cells was found to be ∼3.4%, however the sample with larger nanoparticles exhibit better performance. The analysis of the current-voltage (I-V) measurements vs illumination intensity let us conclude that the surface recombination deteriorates their performance. The measurements of capacitance-voltage (C-V) characteristics allowed us to determine the concentration of donors in ZnO and built-in voltage at the ZnO/Si interface. The deep level transient spectroscopy (DLTS) measurements confirmed the presence of defects at the surface as well as deeper in the ZnO nanorods. Obtained results compared with the data reported elsewhere let us conclude that the defect density is much less than in the case of similar heterojunction ZnO/Si solar cells made by other technological methods.

In this work we discuss a method of preparation of a highly sensitive light detector based on ZnO nanorods. A photoresistor constructed by us is based on a heterojunction between high quality ZnO nanorods and high resistivity p-type Si used as a substrate for nanorods’ deposition. ZnO nanorods are grown by a modified version of a microwave assisted hydrothermal method which allows for growth of high quality ZnO nanorods in a few minutes. The obtained photoresistor responds to a wide spectral range of light starting from near infrared (IR) to ultraviolet (UV). Properties of the detector are evaluated. We propose the use of the detector as an optical switch.

The properties of transparent conductive materials based on wide-gap zinc oxide semiconductors are considered, which are promising in their application to photovoltaics and liquid crystal displays. The impact of aluminum doping on the conductivity of thin ZnO films is examined. Temperature studies of the concentration, mobility, and resistivity in the temperature range of 77–300 K are conducted, revealing the metal conductivity of highly doped films. The electroactivity of aluminum as a donor impurity in the ZnO lattice is studied for thin films grown using atomic layer deposition on glass and silicone, containing 1–7 at. % aluminum. The reasons behind the low electroactivity of Al in ZnO are discussed, as are the methods for its enhancement.

In order to improve the efficiency of a solar cell based on silicon, one must find a compromise between its price and crystalline quality. That is precisely why the knowledge of defects present in the material is of primary importance. This paper studies the defects in commercially available cheap Schottky titanium/gold silicon wafers. The electrical properties of the diodes were defined by using current–voltage and capacitance–voltage measurements. Low series resistance and ideality factor are proofs of the good quality of the sample. The concentration of the acceptors is in accordance with the manufacturer’s specifications. Deep level transient spectroscopy measurements were used to identify the defects. Three hole traps were found with activation energies equal to 0.093 eV, 0.379 eV, and 0.535 eV. Comparing the values with the available literature, the defects were determined as connected to the presence of iron interstitials in the silicon. The quality of the silicon wafer seems good enough to use it as a substrate for the solar cell heterojunctions.

Low temperature (at 100 °C and below) growth of ZnO thin films by atomic layer deposition (ALD) is demonstrated. Properties of the layers grown with two different oxygen reagents: ozone and water are compared. Diethylzinc (DEZ) was used as metal precursor. Electrical and structural properties of films obtained at several different growth temperatures, ranging from 50 °C to 250 °C were analyzed. It turned out that the film grown in the water-based process at 250 °C and all films grown with ozone have more ordered crystallographic structure with the privileged growth direction (001) perpendicular to the substrate than water-based samples grown in temperatures 100−200 °C. Higher free electron concentration at room temperature was observed for ozone-based samples grown at 100 °C and 150 °C in comparison to water-based samples obtained at the same growth temperature. Low value of resistivity in case of ozone-based samples grown at 100 °C is a promising result, however lower electron mobility requires further optimization.

The use of plasmonic inclusions in heterojunction solar cells promises increase of solar-to-electric energy conversion efficiency. Recently, solar cells with ZnO nanorods attracted a lot of attention due to improved efficiency provided by highly scattering ZnO nanostructures on silicon or perovskite. N-type ZnO nanorods are grown on p-Si monocrystalline 180 μm thick substrates among others by means of a hydrothermal technique which requires prior seeding by deposition of thin film of ZnO or noble metals. In the latter case, naturally formed metal islands can also act as plasmonic nanoparticles (NPs). Excitation of plasmonic resonance on the NPs leads to directional scattering of light towards Si layer and electromagnetic field enhancement at their vicinity, close to the ZnO-Si junction, what results in improved energy absorption in the semiconductor layer and thus energy conversion efficiency. In this study, we investigate optimal conditions at which plasmonic phenomenon further improves light trapping in the Si-ZnO solar cells. In simulations performed by means of 3D FDTD method, we calculate light absorption enhancement in the system due to plasmonic NPs used as a seed layer at the ZnO/Si. In the calculations Ag, and Al NPs of different size and geometry close to that achievable in the experiment are analyzed. Finally, numerical results taking into account the granulometry of metal NPs achieved in the experiment are compared with the efficiency of fabricated cells.

Our studies focus on test structures for photovoltaic applications based on zinc oxide nanorods grown using a low-temperature hydrothermal method on a p-type silicon substrate. The nanorods were covered with silver nanoparticles of two diameters – 20–30 nm and 50–60 nm – using a sputtering method. Scanning electron microscopy (SEM) micrographs showed that the deposited nanoparticles had the same diameters. The densities of the nanorods were obtained by means of atomic force microscope (AFM) images. SEM images and Raman spectroscopy confirmed the hexagonal wurtzite structure of the nanorods. Photoluminescence measurements proved the good quality of the samples. Afterwards an atomic layer deposition (ALD) method was used to grow ZnO:Al (AZO) layer on top of the nanorods as a transparent electrode and ohmic Au contacts were deposited onto the silicon substrate. For the solar cells prepared in that manner the current-voltage (I-V) characteristics before and after the illumination were measured and their basic performance parameters were determined. It was found that the spectral characteristics of a quantum efficiency exhibit an increase for short wavelengths and this behavior has been linked with the plasmonic effect.

The plasmonic photovoltaic effect of mediation by surface plasmons in the harvesting of solar light energy in metallically surface-nanomodified photodiodes or solar cells is described in the microscopic manner. The experimentally observed increase in the efficiency of the photo-effect due to plasmons is explained by the competition between two opposing effects: that of the field concentration in plasmon oscillations and that of the admittance of indirect inter-band transitions in a semiconductor substrate induced by dipole coupling to plasmons at the nanoscale without translational invariance. The former effect favors larger metallic nanocomponents, whereas the latter effect prefers smaller nanocomponents. Both factors are quantitatively addressed within the quantum Fermi golden rule scheme, which allows for the size analysis of the plasmon effect and for its optimization. Experimental verification of the theoretical predictions is presented, including the demonstration of the proximity and size effect in double-layer photo-active substrate. The experiment reveals that the plasmon effect is still present if metallic nanoparticles are separated from substrate by the distance of order of 1 μm.

The theoretical approach towards improving the photovoltaic response of n-ZnO/p-Si heterojunctions proposed by Knutsen et al. [Phys. Status Solidi A 210 (2013) 585–588] has been experimentally tested. AZO/n-Zn(1−x)MgxO layers were deposited at 160 °C on p-Si substrates by atomic layer deposition (ALD) with magnesium concentration in the 0–4 at% range. The examined devices showed a reduction of the conduction band offset from (0.63±0.03) eV to (0.48±0.03) eV. This decrease leads to a diminishing impact of recombination centers at the interface between zinc oxide based layers and silicon substrate, when the Mg content is below ~1.6 at%. In this range, the overall photovoltaic efficiency increased from ~3.7% to ~6.0%. As a next step, we tested solar cells with similar magnesium concentration in the Zn(1−x)MgxO layer, but deposited at 300 °C. Due to the higher deposition temperature, a further 1.1% increase in efficiency has been obtained. So far, this is the highest reported efficiency for a ZnO/Si heterojunction grown by ALD method, thus experimentally confirming the validity of the approache s here studied for raising the efficiency of heterojunctions solar cells based on n-ZnO/p-Si, while significantly reducing the fabrication complexity respect to conventional Si based devices as emphasized by Hussain et al. [Sol. Energy Mater. Sol. Cells 139 (2015) 95–100].

This paper is devoted to the development of standard and inverted polymer solar cells based on polyazomethine (PAZ-Car-TPA), poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C 61 butyric acid methyl ester (PCBM). We analyzed the influence of: (i) PEDOT:PSS or MoO 3 as a hole transporting layer in standard devices, (ii) aluminum doping level (from 0 to 3.7%) in ZnO (obtained by atomic layer deposition, ALD) applied as an electron transporting layer in inverted solar cells and (iii) the method applied to obtain ZnO layer (ALD or sol-gel) on its photovoltaic properties. The best device configuration is ITO/AZO (3% Al)/P3HT:PCBM/MoO 3 /Ag which exhibits a power conversion efficiency of 1.51% under about 100 mW/cm 2 AM 1.5 G simulated solar emission. Devices were additionally tested by electrochemical impedance spectroscopy. HOMO-LUMO levels of PAZ-Car-TPA and its mixture with HCl, H 2 SO 4 , p-toluenesulfonic acid, PEDOT:PSS and water were analyzed by cyclic voltammetry and quantum mechanical calculations using Density Functional Theory method.

Over recent years, the use and development of surfactants and biopolymers has been increased. The interactions between oppositely charged polymers and surfactants lead to the formation of the polymer-surfactant complexes. In this work we focused on studying if different types of cationic surfactants such as hydrocarbon, fluorinated and silicone ones can interact with natural polysaccharide - κ-carrageenan. The conducted tensiometric studies have proven that carrageenan forms the complexes with all of the studied surfactants. In the following part we have studied if and how the pre-formed complexes adsorb on the alumina surface. The conducted adsorption experiments indicated that the polymer-surfactant complexes adsorb on the alumina surface via polymer part, and that the process is governed by the electrostatic and non-electrostatic interactions. The results show that the adsorption of carrageenan increased in the presence of the studied surfactants, likewise the adsorption of the surfactants increased in the presence of carrageenan. Moreover, the influence of the hydrocarbon, fluorinated and silicone surfactants on stability and the zeta potential of the carrageenan/alumina suspensions were studied. The addition of carrageenan to the alumina suspensions leads to the increased stability due to the combination of the electrosteric and depletion stabilizations, whereas the presence of surfactants influenced stability only to a small extent. The obtained results have important implications for stabilization of colloidal systems and preparation of different functionalized materials. The findings of our research are very important in the field of preparation of different colloidal dispersions such as cosmetics, pharmaceuticals, and other useful (bio-)materials.

In the present work we studied the mechanical properties of hafnium dioxide (HfO2) and aluminium oxide (Al2O3) thin films deposited on glass at low temperature by means of atomic layer deposition method. The scratch resistance and tribological properties of HfO2 and Al2O3 were investigated. During scratch tests the first small cracks in the films were detected with a relatively low load of 3.4–4.9 N. However, up to a load of 30 N, crushing, cracking, and delamination of the Al2O3/glass system not occurs. The tribological experiments revealed a significant difference in the wear between the HfO2 and Al2O3 films. The microcrystalline structure observed for HfO2 resulted in better tribological properties than the Al2O3 film. The addition of a thin zinc oxide interlayer significantly improved the mechanical properties of the system with HfO2 film.

In this work, well-aligned vertical ZnO nanorod (ZnO NRs) on p-type Si substrate was fabricated by a microwave-assisted hydrothermal reactor to study the coal mine methane (CMM) gas sensing properties. The XRD diffraction peaks and Raman spectra of the ZnO NRs confirmed the hexagonal wurtzite structure with strong preferential orientation along the c axis and well crystal quality. SEM analysis showed NRs with 100 nm average diameter and ~600 nm length. The variations of the sensor electrical resistance in the presence of CMM were investigated at different gas concentrations and various temperatures in the dark and under UV light. The selectivity and response time of the sensor to CMM gas were improved under UV irradiation. The optimal operating temperatures were 225 °C and 100 °C in dark and exposing UV-irradiation, respectively. Also the response of ZnO NRs sensor under UV excitation in humid condition was higher. The sensor was more selective to CMM than CO2. The sensor stability was considered by repeating CMM detection for 90 days.

Structured Silicon layers are used to improve light harvesting by Si-based solar cells. Microstructure of Si is obtained by a selective Si etching using aggressive solvents (acids like HF). In the approach discussed in this work a simplified architecture of solar cells is discussed. A structured electrode is formed by deposition of ZnO nanorods on top of p-type Si. This modification eliminates energy consuming and environmental unfriendly technological steps, as discussed. The so-obtained 3D top electrode consists of n-type ZnO:Al (AZO) layer grown on ZnMgO coated zinc oxide nanorods. AZO and ZnMgO films are deposited by Atomic Layer Deposition method (ALD). Advantages of this technique are first discussed. Several possible applications of the ALD are reviewed.

In this paper, cheap and efficient photovoltaic cells based on ZnO/Si heterostructure are discussed. These cells contain zinc oxide nanorods (ZnONR) grown by a low temperature hydrothermal method on a p-type silicon surface. The hydrothermal method applied in the present work uses cheap precursors and allows reproducible and controllable growth of 3D systems. As-grown ZnONR on Si surface are uniformly covered by a zinc oxide (ZnO) layer followed by an aluminum doped zinc oxide (AZO) layer. The latter is deposited on top of the cell as transparent conductive oxide (TCO). Both zinc oxide and aluminum doped zinc oxide layers are grown by a low temperature atomic layer deposition (LT ALD) method. Thickness of ZnO layers is optimized to increase significantly the light-trapping effect and thus the photovoltaic (PV) response. We evaluate impact of ZnO thickness on the PV devices operation. It is found that PV efficiency increases when thickness of the ZnO layer changes from 50 nm to 500 nm. The best response of solar cells is achieved for a sample containing ZnO layer with a thickness equal to 500 nm. The overall photovoltaic response is 10.9% and can be further improved by contact and Si layer optimization.

Thin films of wide band-gap oxides grown by Atomic Layer Deposition (ALD) are suitable for a range of applications. Some of these applications will be presented. First of all, ALD-grown high-k HfO2 is used as a gate oxide in the electronic devices. Moreover, ALD-grown oxides can be used in memory devices, in transparent transistors, or as elements of solar cells. Regarding photovoltaics (PV), ALD-grown thin films of Al2O3 are already used as anti-reflection layers. In addition, thin films of ZnO are tested as replacement of ITO in PV devices. New applications in organic photovoltaics, electronics and optoelectronics are also demonstrated Considering new applications, the same layers, as used in electronics, can also find applications in biology, medicine and in a food industry. This is because layers of high-k oxides show antibacterial activity, as discussed in this work.

Zinc oxide (ZnO) films were used in silicon-based photovoltaic (PV) structures both as an n-type partner to p-type Si and (on top) as a transparent electrode (as a so-called TCO film). Photovoltaic response of such PV structures depends on the electrical properties of n-ZnO films as well as p-Si (100) substrates. The ZnO-based TCO films were deposited by an Atomic Layer Deposition (ALD) method. The films show a high electron concentration (~10 20 cm −3 ) and a relatively high electron mobility (>10 cm 2 /V s). Considering Si, we used fairly cheap commercial substrates with 360 µm thickness, i.e., not optimized for PV cells applications. The best results were obtained for Si substrates with a moderate hole concentration (~10 15 cm −3 ) and resistivity of 10 Ω cm. The photovoltaic efficiency achieved is 4.4%, with the possibility of further improvement.

We report on the properties of photovoltaic (PV) structures based on thin films of n-type zinc oxide grown by atomic layer deposition method on a cheap silicon substrate. Thin films of ZnO are used as n-type partner to p-type Si (110) and, when doped with Al, as a transparent electrode. PV structures with different thicknesses of ZnO layers (from 600 nm to 1600 nm) were deposited to determine the optimal performance of PV structures. The best response we obtained for the structure with ZnO layer thickness of 800 nm. The so-obtained PV structures show 6% efficiency.

Selected properties of photovoltaic (PV) structures based on n-type zinc oxide nanorods grown by a low temperature hydrothermal method on p-type silicon substrates (100) are investigated. PV structures were covered with thin films of Al doped ZnO grown by atomic layer deposition acting as transparent electrodes. The investigated PV structures differ in terms of the shapes and densities of their nanorods. The best response is observed for the structure containing closely-spaced nanorods, which show light conversion efficiency of 3.6%.

ZnO films with high conductivity are obtained by atomic layer deposition for the application in solar cells based on CdS/CdTe/Cu2S films. The parameters of solar cells with ZnO electrode are compared with the ones with Mo. The advantages of ZnO electrode are discussed.

The test structures for photovoltaic (PV) applications based on zinc oxide nanorods (NRs) that were grown using a low-temperature hydrothermal method on p-type silicon substrates (100) covered with Ag nanoparticles (NPs) were studied. The NPs of three different diameters, i.e., 5–10 nm, 20-30 nm, and 50–60 nm, were deposited using a sputtering method. The morphology and crystallinity of the structures were confirmed by scanning electron microscopy and Raman spectroscopy. It was found that the nanorods have a hexagonal wurtzite structure. An analysis of the Raman and photoluminescence spectra permitted the identification of the surface modes at 476 cm−1 and 561 cm−1. The presence of these modes is evidence of nanorods oriented along the wurtzite c-axis. The NRs with Ag NPs were covered with a ZnO:Al (AZO) layer that was grown using the low-temperature atomic layer deposition technique. The AZO layer served as a transparent ohmic contact to the ZnO nanorods. The applicability of the AZO layer for this purpo...