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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.

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%.

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.