Abstract: This paper presents a spectroscopic study on doping
of Vanadyl pathalocyanine (VOPc) by [6,6]-phenyl C61 butyric acid
methyl ester (PCBM). The films are characterized by UV/Vis/NIR
spectroscopy. A drastic increase in the absorption coefficient has
been observed with increasing dopant concentration. Optical
properties of VOPc:PCBM films deposited by spin coating technique
were studied in detail. Optical band gap decreased with the PCBM
incorporation in the VOPc film. Optical band gap calculated from the
absorption spectra decreased from 3.32 eV to 3.26 eV with a
variation of 0–75 % of PCBM concentration in the VOPC films.