Figure 4From: Improved conversion efficiency of Ag2S quantum dot-sensitized solar cells based on TiO2 nanotubes with a ZnO recombination barrier layer UV-vis absorption spectrum of the plain TNT, ZnO/TNT, Ag 2 S( n )/TNT, and Ag 2 S( n )/ZnO/TNT films. n = 2, 4 and 8.Back to article page