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The presently studied substrates for manufacturing freestanding silicon epitaxial layers contained two porous layers with different porosities. The upper layers of significantly lower porosity after annealing provided smooth surfaces for deposition of epitaxial layers and the deeper layers of greater porosity enabling easier exfoliation epitaxial foil. The layered structures have been studied by means of synchrotron diffraction topography and by recording of rocking curves from small local area. The most effective method of revealing defects in freestanding exfoliated layers were Bragg-case projection topographs and ‘zebra’ pattern monochromatic beam topographs providing a map of sample curvature. The samples have been additionally examined by means of high-resolution diffractometry and reflectometry.The porous layers without epitaxial deposition provided strong narrow maximum at low angle side of the substrate maximum common for both of the porous layers. The most probable effect of the deposition of epitaxial layer is the decrease of lattice parameter in the upper layer with lower porosity, which provided the maxima in the diffraction curves located on low angle side of the substrate maximum. The topographic investigations revealed some defects in deposited epitaxial layers, connected with some irregularities of the annealed porous layer. Very characteristic common defects were large caverns, overgrown in the epitaxial process with the diameters of several tenths of micrometers and defects (possibly the overgrown submicron caverns), associated with some bundles of dislocations resolved in the topographs. In layers of large thickness, the characteristic long black and white stripes along have also been observed, which most probably were stacking faults with dislocation loops.

25th European Photovoltaic Solar Energy Conference and Exhibition / 5th World Conference on Photovoltaic Energy Conversion, 6-10 September 2010, Valencia, Spain; 587-590, Aim of this work is to develop Luminescent Solar Concentrator (LSC) matrix material suitable to absorb NIR and visible part of solar spectrum and emit light within Si absorption range. The synthesis of transparent material by the incorporation of clusters of Nd:Yb:YAG; Nd:Yb:GGG and Nd:Yb:Y2O3 nanocrystals into polymethyl mathacrylate (PMMA) polymer matrix and their subsequent characterization are presented. The redispersion of nanocrystals was done by ultrasonification directly in methyl methacrylate monomer (MMA). The influence of surface active agents has been analyzed in selected samples. Agglomerate sizes after redispersion process were in the range of 10 nm to 100nm. The good optical quality samples has been obtained by using UV polymerization process. Strong fluorescence signal from Yb3+ ions with main peak centered at 1026 nm was observed by direct excitation of Yb3+ ions at 970 nm as well as by excitation of Nd3+ ions at 808 nm. Spectral characteristics are presented and discussed. The results indicate that investigated polymer materials with rare earth contained oxide nanocrystals can be used for NIR conversion for silicon PV application.

25th European Photovoltaic Solar Energy Conference and Exhibition / 5th World Conference on Photovoltaic Energy Conversion, 6-10 September 2010, Valencia, Spain; 599-602, The nanocrystals of Y3Al5O12 (YAG), Gd3Ga5O12 (GGG) and Y2O3 (YO) compounds were prepared via (Pechini) modified sol-gel method. Mentioned oxides were co-doped by 3% Nd and 15% Yb rare ions. Structure and optical properties of nanopowders were investigated and compared. The crystal structures of samples were characterized by X-ray diffraction (XRD) method. The size and morphology of nanopowders were analyzed by scanning electron microscopy (SEM). The obtained nanopowders had crystalline structure as confirmed by XRD and were single phase. The mean size of the crystallites was evaluated using Scherrer formula. It varied from 10 to 70 nm. Spectroscopic properties of YAG, GGG and YO nanopowders were compared with their single crystal counterparts. The results of spectroscopic and emission dynamic studies prove the usefulness of co-doped nanocrystals for application in Luminescent Solar Concentrators. Recently, the YAG, GGG, YO nanocrystals codoped by Nd and Yb ions were dispersed in polymer matrix in order to obtain luminescent composites which may compete with polymers doped by organic dyes.

24th European Photovoltaic Solar Energy Conference, 21-25 September 2009, Hamburg, Germany; 2611-2614, The presented work reports on epitaxialy grown silicon structures with p-n junction designed for fabrication an edge illuminated solar cells. In this kind of photovoltaic devices sun-light illuminates directly a p-n junction through the edge of the structure. The edge-illuminated PV cell can cooperate with a luminescent solar concentrator (LSC) consisted of a polymer foil doped with a luminescent material. The main motivation of presented work is diminishing the silicon consumption in PV panels. We have proposed a new concept of edge illuminated solar cells based on silicon epitaxial technique. The technological factors affecting the cells I-V characteristics and efficiency are discussed.

A mean value of 339 L mol-1 s-1 was obtained for the propagation const. derived from pulsed-laser polymn. (PLP) of styrene in aq. AOT microemulsions. For accurate detns., simulations accounting for the esp. high radical concn. after the laser pulse in microemulsions were recommended. PLP with microemulsions apparently permitted specific kinetic aspects such as transfer to monomer and influence of droplet size on bimol. termination to be studied in detail