Different approaches are under elaboration aimed at the cost reduction of solar electricity. 3D penetrating emitter solar cells are expected to offer performance enhancement at lower costs, using low carrier lifetime cheaper silicon. Using laser ablation, we have prepared indium-fluorine-oxide/(n þ pp þ )Cz-Si/ indium-tin-oxide bifacial silicon solar cells with deep (110-120 mm) penetrating V-shaped emitter with aspect ratio of 3-4 (height to half-width of the V-grooves). Compared with the reference cell textured with conventional random pyramids and thus not damaged by laser action, which showed front/rear active area photocurrents of 41.1/33.3 mA cm À2 , V-grooved solar cells showed only slightly less front photocurrent of 40.1-40.7 mA cm À2 , whereas the superior rear photocurrent of 34.2 mA cm À2 . The latter indicates that deep penetrating emitter is especially useful in the case of bifacial solar cells. The best pseudo-efficiency for V-grooved cell of 19.5% with estimated bifaciality of $80% was obtained for the cell that has been subjected to the smallest laser action during Vgrooving. In addition, ray-tracing model was applied to calculate efficiency of light absorption by a V-grooved silicon solar cell for wavelengths in the range from 400 to 1200 nm. The depth of the grooves was varied from 0.05t to wafer's thickness t. The obtained experimental and computational results confirm that the design of crystalline silicon solar cell based on deep penetrating V-shaped emitter makes possible to obtain high-efficiency solar cells even in the case of low-quality silicon wafers.Silicon wafer with deep penetrating V-grooved emitter.

The demand for the development of local laser sintering of nanoparticle arrays is explained by the expanding needs for printed electronics for functional microstructure formation, on heat-sensitive substrates in particular. This work is based on the research into the sintering of arrays of silver nanoparticles synthesized in a spark discharge and deposited on a substrate by focused aerosol flow. The sintering was done by continuous and pulsed lasers with wavelengths 527, 980 and 1054 nm. Sintered samples were studied by measuring the resistivity, cross-section profile area and microstructure features. The highest average conductivity, equal to the half of the bulk silver conductivity, was achieved when sintering by continuous radiation with a wavelength 980 nm. The results showed that when using pulsed radiation the direct heating of nanoparticles in the sample surface layer dominates with the formation of a pore-free conductive layer of around 0.5 μm thick and crystallite of 70–80 nm size. It was found that laser sintering by radiation with a wavelength 527 nm required an order of magnitude lower specific energy costs as compared to the longwave laser radiation. The high energy efficiency of laser sintering is explained by special conditions for radiation absorption at plasmon resonance.

This work is devoted to the sintering of silver nanoparticle arrays in the form of lines by the local treatment with laser radiation with wavelengths of 527, 1054 and 1064 nm in pulsed and continuous laser modes. The silver nanoparticle lines were formed by the dry aerosol printing, free from organic solvents and surfactants. To form the lines with a width of 25–300 μm and a thickness of 0.1–15 μm a focused stream of nanoparticles with an average size of about 60 nm was used. It is shown that when using continuous laser radiation with a wavelength of 1064 nm, the minimal specific resistance of silver nanoparticle lines was achieved 3 times higher than that for the bulk material was reached.

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