Sulfur-doped molybdenum oxide anode interface layer for organic solar cell application.

Efficient organic solar cells (OSCs) based on regioregular of poly (3-hexylthiophene):fullerene derivative [6,6]-phenyl-C61butyric acid methyl ester composites have been fabricated on indium tin oxide (ITO) coated glass substrates by using a sputtered sulfur-doped molybdenum oxide (S-MoO3) film as anode interface layer (AIL). With the help of X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy, we find that oxygen flow ratio control can modulate the amount of sulfur doping into MoO3, then further tune the Mo+4/Mo+5/Mo+6 composition ratios, Fermi level, electron affinity, valence band ionization energy and band gap of MoO3. A partially occupied Mo 4d-bands of Mo5+ and Mo4+ states modulated by sulfur doping are the main factor which influences the valence electronic structure of S-MoO3.These orbitals overlap interrelation push the valence band close to S-MoO3’s Fermi level, thus make it into a p-type semiconductor. S-MoO3 with smaller ionization energy and electron affinity is better...