Highly photosensitive thienoacene single crystal microplate transistors via optimized dielectric

• The mobility and stability of Ph5T2 single crystal field-effect transistors have been improved via dielectric optimization.
• The PMMA dielectric devices show the high mobility and the best operational stability without hysteresis effect.
• The Ph5T2 phototransistor has the high photosensitivity at 21 mA W−1 and the extremely high photocurrent gain at 6.8 × 105.

High photosensitivity and high photocurrent gain have been obtained based on dielectric optimized dinaphtho[3,4-d:3′,4′-d′]benzo[1,2-b:4,5-b′]dithiophene (Ph5T2) single crystal microplate transistors. In our experiments, the PMMA dielectric device shows the best operational stability without hysteresis effect. Based on such an optimized device, the photoelectric properties of the Ph5T2 single crystal microplates have been studied for the first time. The Ph5T2 phototransistor has the high photosensitivity at 21 mA W−1 and the extremely high photocurrent gain (Ilight/Idark) at 6.8 × 105. The photocurrent gain is higher than that of the most reported organic phototransistors (OPTs), and is in a class with the highest photocurrent gain for the reported values so far. This confirms that Ph5T2 is a photosensitive material and shows it promising potential in photoswitches and phototransistors.

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