Characteristics of an infrared sensor formed with a few molecular layers of vinylidene fluoride oligomers with in situ poling during vacuum evaporation

Abstract

Abstract Perpendicularly oriented vinylidene fluoride oligomer thin films with six molecular layers were poled during vacuum evaporation (in situ poling) using a micro-gapped comb-like electrode, and their pyroelectric characteristics were investigated. The extent of polarization achieved with in situ poling performed by applying a low electric field (7.7 MV m−1) is the same as that achieved by conventional post-poling with the application of a high electric field (>100 MV m−1). Despite using a film with a few molecular layers, the in situ poled sensor showed pyroelectric response without the use of an infrared ray absorption layer; voltage sensitivity of 198 V W−1 was obtained, which is much higher than that of the post-poled sensor (∼16 V W−1). The improvement in sensitivity is attributed to the amount of charge injected during the poling treatment.