Humidity effect on electrical performance of organic thin-film transistors

Humidity dependence of electrical performance of $p$ -channel organic thin-film transistors (OTFTs) with various semiconductor compounds has been investigated. All devices showed decreased current output and mobility as the relative humidity (RH) was increased. The moisture sensitivity of the OTFT saturation current depends on the device geometry (bottom or top contact device) and channel length. The OTFT configuration with a short channel length and bottom contact was most affected by humidity compared to the top contact and larger channel length OTFT structures. The degradation of electrical performance under high RH is attributed to charge trapping at grain boundaries by polar water molecules reducing the rate of charge transport.