Efficiency enhancement of Cu(In,Ga)Se2 solar cells fabricated on flexible polyimide substrates using alkali-silicate glass thin layers

Cu(In,Ga)Se-2 (CIGS) absorber layers were grown at a maximum substrate temperature of 400 degrees C on polyimide (PI) films. The PI films were formed by spin-coating on glass substrates. Alkali doping into the CIGS layers was demonstrated using alkali-silicate glass thin layers (hereafter called ASTL) deposited on PI films prior to the sputtering of the Mo back contact layer. The quantum efficiency curves of CIGS solar cells fabricated with use of ASTL showed an enhanced absorption in the long wavelength region. Using the ASTL method, the cell efficiency of 14.7% has been demonstrated on PI substrate. (C) 2008 The Japan Society of Applied Physics.