Физика UDC 535.215 Illumination-Induced Degradation of a-Si:H Solar Cell Parameters I. M. Kashirskiy∗, Y. G. Michael† ∗ Department of General Physics Peoples’ Friendship University of Russia Mikluho-Macklaya str., 6, Moscow, 117198, Russia † Division of Natural and Social Sciences Alemaya Unversity of Agriculture Diredawa, Ethiopia Hydrogenated amorphous silicon is found to be a leading candidate for the fabrication of low cost solar cells. <...> However presently there are two main factors that limit the large scale applications of a-Si:H solar cells as power sources. <...> One of the central technological obstacle is the low conversion efficiency of the cells. <...> The other obstacle for the large scale technological application of a-Si:H solar cells is degradation of critical material properties under the light exposure. <...> The pattern of light induced degradation, i.e. the degree of degradation of a-Si:H pinpin solar cell parameters was studied on different i-layer thickness using high intensity (∼10 AM 1.5) illumination. <...> It was found that stacked cells do not show a uniform degradation pattern as in the case of single junction solar cells. <...> In particular, the degradation in short-circuit current Isc of stacked cells shows a big difference for thick (∼500 nm) and thin (∼400 nm) pinpin cells. <...> It was found the degradation of the stacked cells with thick bottom layers exhibit a degradation pattern similar to that of single junction cells, i.e. the degradation in efficiency comes from the fill factor and the short circuit current, while open circuit voltage being degraded slightly. <...> The degradation in short circuit current of cells with thin bottom layers is negligibly small. <...> Key words and phrases: pattern of degradation, solar cells, fill factor, efficiency, short circuit current, open circuit voltage, photo-degradation, multi-junction cells. 1. <...> Stacked, multijunction solar cells are thus thought to be the most promising technology to obtain a-Si solar cells with high reliability and high efficiency [1]. <...> Consequently, significant progresses have been made towards the improvement of the initial conversion efficiency as well as the light instability. <...> Yet, for more reduction <...>