Real time monitoring of ordering in pentacene films during growth by using in-situ infrared spectroscopy

By employing the in-situ Fourier transform infrared (FTIR) spectroscopy and curve-fitting, we studied the evolution in the ordering of vacuum-deposited pentacene films. In the FTIR spectra, the thin film and bulk phases appeared at 903.2 cm−1 and 907.2 cm−1, respectively. The misoriented phase was also observed at 904.4 cm−1. The position and the intensity of each phase varied with the film thickness as well as the growth temperature. The results indicated that most of pentacene molecules formed initially the thin film phase until the bulk and misoriented phases began to form at the increased thickness. Our study suggests that FTIR spectroscopy is an effective tool to monitor in real time the ordering of organic films for quality control.