Enhancement and broadening of near infrared photoluminescence in Ag2X (X= S, Se) quantum dots via Cd doping for mini light-emitting diodes towads non-invasive bioimaging

Exploring excellent NIR-II emitting materials is desirable for the advancement of high quality bioimaging, in virtue of the lower scattering, deep penetration and high sensitive of biological components in the second optical transmission window. Colloidal Ag 2 X (X = S, Se) nanocrystals exhibit tunable NIR photoluminescence in the second NIR region. However, the lack of highly efficient broadband NIR emitting Ag 2 X (X = S, Se) nanocrystals limits their spectroscopy applications. Herein, cadmium (Cd) doped Ag 2 X (X = S, Se) nanocrystals were prepared through a facile hydrothermal method at room temperature. The NIR luminescence was efficiently enhanced through controllable doping a little amount of Cd ions into the Ag 2 X (X = S, Se) quantum dots (QDs). Simultaneously, the great broadening of NIR emission was achieved in the Cd doped Ag 2 Se QDs, and the maximum full width at half maximum could reach up to 530 nm. Following the general principles of PL LED devices, the fabricated NIR mini light-emitting diodes (LEDs) light sources based on Cd doped Ag 2 Se QDs exhibited broadband NIR electroluminescence and superior optoelectronic stability, and were successfully employed for clear vessel imaging. The works proves the feasibility of NIR mini LEDs in non-invasive bioimaging, and paves way for the miniaturized broadband NIR light sources. • NIR emission of Ag 2 X (X = S, Se) QDs are enhanced more than 3 times via Cd doping. • Broadband Dual NIR emission of Cd doped Ag 2 Se QDs covers the entire NIR-II region. • The addition of Cd ions induces the variation of bandgap energy of Ag 2 Se QDs. • Micron-scale non-invasive vessel imaging is achieved by doped QDs converted NIR LED.