Effects of Deflection on the Sio_2 Barrier Layer and Mo Back Electrode of Cu(In,Ga)Se_2 Thin-Film Solar Cells on Stainless Steel Substrates

This paper studies the effects of deflection on the SiO2 barrier layer and molybdenum(Mo)back electrode of Cu(In,Ga)Se2 thin-film solar cells,prepared via magnetron sputtering on type SUS431 stainless steel substrates.The surface micro-cracks and sheet resistance of thin films had been observed and measured for in-situ bend tests.Experimental results show that increasing the thickness of the SiOx barrier has a better property to prevent cracks induced by bending stress.The sheet resistance of a Mo film increases alongside the bending of the curvature radius.The maximum allowed value of the curvature radius of the SiOx barrier layer,molybdenum electrodes,and the thin film CIGS absorbing layer should be 16 mm,20 mm,and 26 mm,respectively.Therefore,the maximum curvature radius limit should be 26 mm or less for CIGS thin-film solar cells prepared via sputtering on type SUS431 stainless steel substrates.

On the Optimization of Performance of Hg_xCd_(1-x)S Based Electrochemical Photosensing Cell

Chemical growth process that favours deposition of semiconductor materials from a liquid phase was used to obtain CdS and HgxCd1-xS(0≤x≤0.25)photosensitive thin film electrodes on the stainless steel substrates.The deposition of these series of thin films was carried out under the optimized conditions of temperature(60℃),time(90 min)and pH(10.8±0.2).These films were then employed as photosensitive electrode in an electrochemical photosensing cell consisting of sulphide/polysulphide redox electrolyte and a graphite counter electrode.The cells were illuminated by an input illumination intensity of 13 mW/cm 2 and the cell characteristic parameters namely photocurrent(Iph),photo voltage(Vph),the quantum conversion efficiency(η%)and fill factor(ff %)have been determined.Both Vph and Iph have been found to be boosted as the electrode composition is altered.The conversion efficiency and fill factor enhanced from 0.52%to 1.30%and 31.8%to 37.8%,respectively for the change of electrode composition from 0 to 0.08.Determination of junction ideality factor(nd)showed recombination mechanism at the electrode-electrolyte interface.Barrier height measurements gave Pool-Frenkel type conduction mechanism.The flat band potentials(Vfb)were determined for all the cells and found to be enhanced with x up to 0.08 and then decreased for further increase in x.The lighted junction quality factor(nL)is increased from 1.49 to 2.94 as the photoelectrode composition(x)was varied from 0 to 0.08.The barrier heights(B)at the electrode/electrolyte interfaces were also determined.It is found that B is higher for a cell of electrode composition equal to 0.08.The spectral studies on these cells showed the cut off wavelength(λc)shifted from 530 nm to 800 nm.The transient response studies showed presence of surface states at the interface that causes Fermi-level pinning.Overall,performance of the electrochemical photosensing cell is found to be improved after Hg-corboration in CdS and is optimum at x= 0.08.