Ultrathin semiconductor films for NH3 gas sensors prepared by vertical phase separation

Vertical phase separation of the polymer blendsis a facile method to prepare double-layered polymer films. In this study, ultrathin P3HT films prepared by the vertical phase separation of the P3HT and PMMA blends were reported. The film thickness of P3HT is simply controlled by varying the P3HT/PMMA blend ratio. The thickness of the as-formed ultrathin P3HT films can be as low as around 2.0 nm. The relationship between the P3HT film thickness and charge transport performance was studied. It was found that the mobility decreased slightly with the decrease of P3HT film thickness. The ultrathin P3HT films exhibit good organic field-effect transistor performance with a mobility of 2.3 × 10−2 cm2V-1s-1. The gas sensors based on the ultrathin P3HT films was also investigated. The performance of ammonia sensor improved rapidly as the film thickness decreased and the response of the P3HT ultrathin film with 2.0 nm thickness reaches 31.1%.