Combined Raman and photoluminescence (PL) measurements were performed in situ and online during the formation of a PTCDA-C-60 charge transfer (CT) complex film using organic molecular beam deposition. It is found that two different processes compete during Growth, namely the formation of PTCDA-C-60 CT complexes and the photopolymerization between C-60 molecules. The CT complexes, formed instantaneously upon the co-deposition of two molecules, decompose as the C-60 molecules forming the CT complexes undergo the photopolymerization with excess C-60 molecules. At low coverage, 70% of PTCDA molecules in the film form CT complexes with C-60. The rate of CT complex formation decreases dramatically with the beginning of the photopolymerization after 11 min of deposition. The results prove the importance of preventing the formation of C-60-C-60 pairs in order to keep the maximum ratio of CT complexes in the film under laser irradiation.