A tricolour photodetecting memory device based on lead sulfide colloidal quantum dots floating gate

Phototunable nonvolatile organic memory offers a simple and smart strategy to detect and record optical signals, which provides a promising potential pathway towards the realization of low-cost and highly integrated imaging system. Here, a tricolor photodetecting memory device based on organic field-effect transistor configuration has been developed by employing lead sulfide (PbS) colloidal quantum dots (CQDs) as floating gate. The device shows a large memory window of 18.6 V due to the high charge storage capability of PbS CQDs. When the pre-programmed memory device is illuminated by light irradiation with different wavelengths (blue light λ = 420 nm, green light λ = 550 nm, and red light λ = 650 nm), the transfer curve shifts to a more positive direction as the wavelength decreases, resulting in a higher current when read at a fixed reading voltage, which can be applied in tricolor photodetection. The photodetecting memory mechanism is correlated with the charge transfer between PbS CQDs and pentacene and the charge storage property of PbS CQDs.