Low Operating Voltage Organic Field-Effect Transistors with Gelatin as a Moisture-Induced Ionic Dielectric Layer: The Issues of High Carrier Mobility

Suman Mandal, Ajoy Mandal, Gourhari Jana, Samik Mallik, Satyajit Roy, Arnab Ghosh, Pratim Kumar Chattaraj, Dipak K. Goswami

Research output: Contribution to journalArticlepeer-review

28 Scopus citations

Abstract

We have developed low-voltage (<2 V) flexible organic field-effect transistors (OFETs) with high carrier mobility using gelatin as a moisture-induced ionic gate dielectric system. Ionic concentration in the gelatin layer depends on the relative humidity condition during the measurement. The capacitance of the dielectric layer used for the calculation of field-effect carrier mobility for the OFETs crucially depends on the frequency at which the capacitance was measured. The results of frequency-dependent gate capacitance together with the anomalous bias-stress effect have been used to determine the exact frequency at which the carrier mobility should be calculated. The observed carrier mobility of the devices is 0.33 cm2/Vs with the capacitance measured at frequency 20 mHz. It can be overestimated to 14 cm2/Vs with the capacitance measured at 100 kHz. The devices can be used as highly sensitive humidity sensors. About three orders of magnitude variation in device current have been observed on the changes in relative humidity (RH) levels from 10 to 80%. The devices show a fast response with a response and recovery times of ∼100 and ∼110 ms, respectively. The devices are flexible up to a 5 mm bending radius.

Original languageEnglish
Pages (from-to)19727-19736
Number of pages10
JournalACS applied materials & interfaces
Volume12
Issue number17
DOIs
StatePublished - 29 Apr 2020
Externally publishedYes

Bibliographical note

Publisher Copyright:
Copyright © 2020 American Chemical Society.

Keywords

  • biopolymers
  • flexible device
  • humidity sensor
  • mobility overestimation
  • organic field-effect transistors (OFETs)

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