X-Graphene Quantum Dot/PbX (X = S, Se) Hybrid Nanostructures for Self-Powered Two-Color UV-NIR Photodetectors

Self-powered near-infrared (NIR) photodetectors are crucial in various practical applications. In this study, we present the development of two different UV-NIR dual-absorbing nanostructures: (i) composite of sulfur-doped graphene quantum dots (S-GQD) and lead sulfide (PbS), denoted as S-GQD/PbS and (ii) composite of selenium-doped graphene quantum dots (Se-GQD) and lead selenide (PbSe), denoted as Se-GQD/PbSe. These nanostructures were synthesized by using a two-step solvothermal method. The photodetectors fabricated using these nanocomposites can operate over a wide wavelength range, from 400 to 1800 nm, and under zero-bias conditions, a peak NIR responsivity of 1.8 A/W is noted. This result marks the development of superior self-powered NIR photodetectors using colloidal quantum dots. Additionally, these devices exhibit superior performance near UV–visible wavelengths, exhibiting a peak responsivity of 2.5 A/W, demonstrating their potential as high-performing dual-band self-powered colloidal quantum dot-based photodetectors.