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Keywords:

  • Field-effect transistors;
  • organic;
  • Pentacenes;
  • Device performance;
  • Flexible electronics;
  • Thin films;
  • Charge-carrier mobility

Abstract

Organic field-effect transistors suffer from ultra-high operating voltages in addition to their relative low mobility. A general approach to low-operating-voltage organic field-effect transistors (OFETs) using donor/acceptor buffer layers is demonstrated. P-type OFETs with acceptor molecule buffer layers show reduced operating voltages (from 60–100 V to 10–20 V), with mobility up to 0.19 cm2 V−1 s−1 and an on/off ratio of 3 × 106. The subthreshold slopes of the devices are greatly reduced from 5–12 V/decade to 1.68–3 V/decade. This favorable combination of properties means that such OFETs can be operated successfully at voltages below 20 V (|VDS| ≤ 20 V, |VGS| ≤ 20 V). This method also works for n-type semiconductors. The reduced operating voltage and low pinch-off voltage contribute to the improved ordering of the polycrystalline films, reduced grain boundary resistance, and steeper subthreshold slopes.