Simple ultrasonic mixing to obtain charge transfer dopants of graphene oxide for highly responsive photodetectors and efficient image extraction

Regulating the charge-related properties in materials is highly valuable in the field of electronic devices. Charge transfer doping received significant attention as an efficient method of modulation. Graphene oxide (GO) is often used for regulation due to its abundance of oxygen-containing groups. However, the conventional operations to perform charge transfer doping for GO are complex, expensive and environmentally unfriendly. Here, we propose a charge transfer doping strategy by simply mixing GO suspension with 5 mg/ml 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane (F4TCNQ), together with ultrasonic treatment. Notably, the F4TCNQ-GO flexible photodetector exhibits outstanding responsivity (R) of up to 1.57 × 103 A/W in the 650 nm regime, surpassing most of the GO/graphene-based photodetectors reported in the past decade. Moreover, the photodetector successfully realizes in-sensor computing for complex pattern imaging, enabling clear and efficient multi-directional edge extraction. Experiments employing X-ray photoelectron spectra (XPS), X-ray diffraction spectra (XRD), Raman spectra, Ultraviolet–visible (UV–vis) spectra and scanning electron microscopy (SEM) reveal the stable non-covalent binding between GO and F4TCNQ through π-π interactions, as well as the electron transfer from GO to the F4TCNQ molecule, resulting in the formation of electron accumulation and depletion layers on the F4TCNQ molecule and GO, respectively. This finding holds great potential for regulating the electronic properties of a wide range of π-electron-rich two-dimensional materials in the fields of energy, biomedicine, environmental technology, and materials science.