Highly sensitive organic near-infrared phototransistors based on poly(3-hexylthiophene) and PbS quantum dots

Highly sensitive near-infrared (NIR) phototransistors based on poly(3-hexylthiophene) (P3HT) and lead sulfide quantum dots (PbS QDs) were fabricated by a solution process. The phototransistors show high responsivity up to 2 × 104 A W−1 under NIR illumination with wavelength of 895 nm, which is much bigger than that of the photodetectors based on PbS QDs or organic semiconductors only. The sensing mechanism is attributed to the photo-induced electrons generated in the PbS QDs, which increase the threshold voltage of the transistor. These phototransistors may find promising applications as infrared sensors for their high responsivity, easy fabrication, low cost and flexibility.