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Introduction. PECVD enables fabrication of wide range of advanced materials with various structure such as amorphous, polymorphous, nano-crystalline, nanostructured, microcrystalline etc. and with various electronic properties. The latter can be also changed by different dopingl. PECVD silicon materials are commercially employed in multi-layered PV structures (including ones on flexible substrates). Combining these materials with crystalline silicon active substrate resulted in significant improvement of PCE in hetero junction technology PV structures. Existence of new organic semiconductors (OS) together with understanding of physical properties resulted in fast development of OC PV devicesAim. To consider both PECVD and OS materials and to present description of fabrication, structure and electronic properties for device application.Materials and methods. Devices based on non-crystalline materials, devices based on OS, hybrid devices. PECVD and Spin coating technique was used to deposit materials with tunable properties enabling device engineering possibilities.Results. PECVD and OS materials were analyzed. These materials have different levels of characterization (data volume, interpretation of the results etc.) and of understanding of physics determining device performance. Some examples of these materials in PV including structures with crystalline silicon were considered.Conclusion. Important advantage of both PECVD and OS materials is that fabrication methods are compatible and allow fabrication of great variety of hybrid device structures on crystalline semiconductors. Advantages of such devices are difficult to predict because of lack of data in scientific literature. However a new area in material science and related devices for further exploring and exploiting has appeared.

Electrochemical capacitance–voltage profiling has been used to examine heterojunction solar cells based on single-crystal silicon. Specific features of the electrochemical capacitance–voltage profiling of modern multilayer heterojunction solar cells have been analyzed. The distribution profiles of majority carriers across the whole thickness of the samples were obtained, including, for the first time, those in layers of conducting indium tin oxide.

The operating characteristics of heterojunction solar cells based on single-crystal silicon wafers with a reduced thickness are investigated experimentally. It is found that a decrease in the wafer thickness by 40% as compared to the standard values leads to degradation of the photoelectric-conversion efficiency to 5%. The obtained results could be used for estimating the commercial feasibility of the production of solar cells with a reduced wafer thickness.

Solar cells made of silicon wafers have dominated the terrestrial photovoltaic (PV) market since the beginning of industrial commercialization of PV.

The photoinduced degradation of photovoltaic converters based on an a-Si:H/µc-Si:H tandem structure under a standard illuminance of 1000 W/m2 is studied. The spectral and current–voltage characteristics of specially fabricated samples with various degrees of crystallinity of the intrinsic layer in the lower (microcrystalline) cascade are measured in the course of the tests.

The spectral characteristics of the photoresponse of heterostructures with layers of densely packed amorphous silicon nanoparticles produced by laser electrodispersion are studied. The structures exhibit rectifying properties. Annealing in air results in the appearance of silicon oxide nanoparticles in the layers and, in addition, there occurs partial crystallization of the nanoparticles. The spectral characteristics of the photoresponse of the heterostructures have a number of specific features. Compared with standard silicon photodiodes, the sensitivity spectra of the structures under study are shifted to shorter wavelengths, with the shift becoming more pronounced upon annealing. The structures with an annealed layer of nanoparticles exhibit sensitivity in the spectral range 350–600 nm, which exceeds by more than an order of magnitude the sensitivity of unannealed structures. This effect can be attributed to a transistor-like effect in the structure.

The study of films consisting of amorphous close-packed silicon nanoparticles grown by laser electrodispersion is continued. The optical transmission and reflection spectra of films fabricated in vacuum and at various pressures of oxygen introduced into the chamber to passivate the nanoparticle surface are measured. The spectra of the refractive index and extinction coefficient are calculated. The shape of the spectra of the optical constants correlates with that of the spectra of bulk amorphous silicon; however, the values obtained differ from the parameters of bulk amorphous silicon. The differences are caused by the significant volume of voids between nanoparticles and a large number of dangling bonds (defects) on the nanoparticle surface. The optical constants decrease with increasing oxygen content in the films, which is indicative of the passivation of dangling bonds by oxygen.

Portable power source based on air-hydrogen fuel cells (FCs) operating in a free-breathing cathode regime has been developed. At a volume of 100 cm3, the source has a power capacity of 8.5 W h and generates a power of 2 W that is independent of the temperature within 5–40°C and the relative humidity of the ambient air within 40–98%. With respect to the specific energy characteristics, the proposed PTI type device exceeds other air-hydrogen FCs and in some respects is even superior to power sources based on air-methanol FCs.

We have studied the characteristics of small-scale air-hydrogen fuel cells (FCs) operating in a free-breathing cathode regime. The cells are provided with a new gas-distributing element on the cathode side, which is based on a silicon plate with narrow through slots (slotted Si plate). It is shown that the use of a slotted Si plate significantly weakens the dependence of the FC characteristics on the humidity of environment in a broad temperature range. Indeed, at a fixed temperature, the FC power only changed within 10% when the relative humidity of the ambient air varied between 50 and 98%.

Modulation-doped CdTe/Cd0.7Mg0.3Te quantum well structures with a two dimensional electron gas of low and moderate density (from ne = 3 × 1010 cm–2 up to ne ≈ 1012 cm–2) have been studied. Photoluminescence spectra taken from the quantum well in magnetic fields from 0 T to 45 T at different electron densities were studied. The observed spectra were analyzed in terms of combined exciton-electron processes. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The temperature-induced variations in the photoluminescence spectra measured in a magnetic field of trions and excitons in CdTe/CdMgTe quantum wells with modulated doping are studied. It is found that the temperature-induced redistribution of the intensity between the exciton and trion emission lines in a magnetic field is opposite to that expected from the simple Boltzmann distribution model. Coupled rate equations for the trion-exciton system are solved to construct the temperature dependences of the exciton and trion emission line intensities. The relations thus calculated are in good agreement with experiment.

Modifications of photoluminescence (PL) spectra taken from modulation doped CdTe/CdMgTe quantum well (QW) structures have been studied in magnetic fields up to 45T as a function of 2D electron concentration.

Photoluminescence (PL) spectra of modulation-doped CdTe/CdMgTe quantum-well structures containing two dimensional electron gases with electron concentrations around 1010 cm–2 have been recorded under a high magnetic field up to 45 T. Radiative recombination lines of dark and bright triplet trion states were found in the spectra at magnetic field strengths larger than 20 T. A model that takes into account the full symmetry of the structure under the magnetic field fits all the experimental results. Recording reflectivity spectra confirms the proposed model and the results from PL experiments. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Modifications of photoluminescence (PL) and Reflectivity (Ref) spectra taken from modulation doped CdTe/CdMgTe quantum well (QW) structures have been studied in magnetic fields up to 45T as a function of 2D electron concentration.

Combined exciton–electron processes were found and studied in reflectivity and photoluminescence spectra taken from modulation-doped quantum well structures with different 2DEG densities. At low magnetic fields a Stokes shift between reflectivity and PL exciton and trion peaks due to the renormalization of the exciton and trion self-energy have been found. This shift disappears at high magnetic fields.

Surface effects, in particular oxygen passivation, are known to have drastic influence on emission spectra of semiconductor nanoclusters. The goal of this work was to obtain light emission from amorphous silicon nanoclusters by means of oxygen passivation. Granulated films of amorphous silicon nanoclusters were fabricated by the laser electrodispersion technique, which allows obtaining nanoclusters of uniform sizes. Two methods were applied in order to incorporate oxygen into the films, and both result in improvement of the luminescent properties of the films. The role of oxygen passivation as well as the effect of thermal annealing is considered. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Photo-induced degradation of tandem α-Si: H/μc-Si: H photoconverters under standard light flux densities of 1000 W/m2 (AM1.5G) have been investigated. Spectral and current-voltage characteristics of solar modules produced with standard and modified recipes are presented and analyzed. This research is dedicated to the optimization of crystallization level in intrinsic layer of lower (microcrystalline) cascade.

Silicon heterojunction solar cells (HJSC) with the efficiency of about 20% are manufactured. Their short-circuit current, open-circuit voltage, photoconversion efficiency, and fill factor of the current–voltage curve are measured in a broad temperature range from 80 to 420 K. It is established that the open-circuit voltage, the fill factor, and the photoconversion efficiency are non-monotonic functions of temperature, having a maximum in the vicinity of 200 K. A new approach to modeling of HJSCs is proposed, which allows one to obtain quantitative agreement with the experimental results at temperatures above 200 K, as well as to describe the results published in the literature on the solar cells under AM1.5 conditions. The temperature coefficient of photoconversion efficiency in HJSCs is discussed, and its low value is shown to be related to the low surface and volume recombination rates. Finally, a theoretical expression for the SC's temperature under natural working conditions is derived.

Modifications of photoluminescence (PL) spectra taken from modulation doped CdTe/CdMgTe quantum well (QW) structures have been studied in magnetic fields up to 45T as a function of 2D electron concentration.