New ceramic pigments based on the tialite (Al 2 TiO 5 ) structure, doped with Co (pink), Cr (green), or Mn (brown), were prepared through the pyrolysis of aerosols followed by calcination of the obtained powders at 14001C. The expected decomposition of Al 2 TiO 5 into a mixture of Al 2 O 3 and TiO 2 on refiring was inhibited by Cr-doping and also by co-doping with Mg the Mn-or Co-doped samples. Microstructure and phase evolution during pigment preparation were monitored by scanning electron microscopy and XRPD. Unit cell parameters of tialite were determined by Rietveld refinement of the X-ray diffraction patterns, revealing in all cases the formation of solid solutions where the solubility of dopants in the Al 2 TiO 5 lattice followed the trend CooMnoCr. The valence state and possible location of dopants in the tialite lattice were investigated by X-ray photoelectron spectra and diffuse reflectance spectroscopies, which suggested the presence of Cr 31 ions in a large interstitial site of the tialite lattice with a distorted octahedral geometry, and of Mn 31 and Co 21 ions in the Al 31 octahedral sites of the tialite lattice in the former case, and in both Al 31 and Ti 41 octahedral sites in the latter. Testing the ceramic glazes assessed the technological behavior of pigments, which found that the color stability was reasonably good for the Mn-doped tialite and the Crdoped pigment, although the latter suffered a small loss of green hue. The Co-doped pigment was found to be not stable in glazes, undergoing a cobalt-leaching effect. P. Davies-contributing editor

This report studies the influence of alkali elements (Na, K) to morphological, structural and optoelectronic properties of CIGS ceramic tile solar cell. Several ceramic enamels with altered chemical composition in terms of amount of alkali elements have been tested and compared. The influences of alkali type, its quantity and transfer mechanism have been investigated. The solar cell device has been assembled and characterized. The achieved results indicate that alkali elements (Na and K combination) modified the surface roughness and its diffusion from the enamel toward the absorber affect to the structural and final optoelectronic properties of the device. The alkali doping improve the Ga incorporation in the crystal lattice and an increasing in open circuit voltage (Voc) values, fill factor (FF) and the device efficiency. Optimal alkali quantities have been also determined. The best conversion efficiency is achieved for the cell with 4% wt Na 2 O and 3.2 % wt K 2 O (Eff. = 3,5 %), which presents an improvement of 30 % in efficiency relative to the standard (STD) solar cell sample chosen for comparative purposes.

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In this work the use of porcelain stoneware tiles as alternative substrates for CIGS thin film solar cells for the development of specific applications as those related to building integration (BIPV, BAPV) are reported. Two types of porcelain stoneware have been compared: the conventional tile (STD) and the ecological tile (ECO). The ECO ceramic paste formulation has been designed adding industrial wastes (recycled glass, sludges and chamote). Chemical, technological and functional properties of the paste have been performed. The CIGS absorber has been synthesized by an easy and low-cost way of preparation using co-precipitation method. The solar cell device has been completed and fully characterized.The achieved results indicate better performances for ECO paste compared to the STD, stated in improved mechanical resistance, thickness and morphology. It is demonstrated 2 that both tiles are suitable for solar cell applications, but ECO substrate developed higher energy conversion efficiency of 1.3 %.

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