Megahertz operation of flexible low-voltage organic thin-film transistors

• Top-contact organic TFTs with a channel length of 1 μm were fabricated on plastics.
• The TFTs have a mobility of 1.2 cm2/V s and an on/off ratio of 107.
• The transconductance has a standard deviation of no more than 6%.
• Ring oscillators have a stage delay of 420 ns at a supply voltage of 3 V.

Bottom-gate, top-contact (inverted staggered) organic thin-film transistors with a channel length of 1 μm have been fabricated on flexible plastic substrates using the vacuum-deposited small-molecule semiconductor 2,9-didecyl-dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (C10-DNTT). The transistors have an effective field-effect mobility of 1.2 cm2/V s, an on/off ratio of 107, a width-normalized transconductance of 1.2 S/m (with a standard deviation of 6%), and a signal propagation delay (measured in 11-stage ring oscillators) of 420 ns per stage at a supply voltage of 3 V. To our knowledge, this is the first time that megahertz operation has been achieved in flexible organic transistors at supply voltages of less than 10 V.

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