Rational design of colloidal AgGaS2/CdSeS core/shell quantum dots for solar energy conversion and light detection

Colloidal quantum dots (QDs) with core/shell architecture can offer tailored electronic and optical properties which are promising for various optoelectronic applications. Here, we report the growth of multifunctional AgGaS2 (AGS)/CdSeS core/shell QDs via a simple two-step synthetic method. In comparison to the bare AGS QDs, as-synthesized core/shell QDs revealed enhanced visible light absorption, red-shifted emission and prolonged exciton lifetime, demonstrating the type II band alignment of the AGS core and CdSeS shell structure for improved charge separation/transfer, as further verified by the measured ultrafast carrier dynamics. The heterostructured core/shell QDs were used to fabricate both the photoelectrochemical (PEC) cells and photodetectors for efficient solar energy conversion and light detection, showing a maximum photocurrent density of ~4.8 mA/cm2 under visible light irradiation and a detectivity of 3.3 × 1010 Jones under wavelength of 510 nm, respectively. These findings indicate that the rational design of core/shell architecture is promising to tailor the optoelectronic properties and band structure of QDs for versatile and high-performance optoelectronic applications. A new type of colloidal AgGaS2 (AGS)/CdSeS core/shell QDs are developed, showing improved visible light absorption, red-shifted emission and extended exciton lifetime as compared to pristine AGS core QDs. The tailored optical properties of such core/shell QDs demonstrate a type II band structure with efficient charge separation and transfer, resulting in high-efficiency QDs-based solar energy conversion and light detection applications. [Display omitted] •AgGaS2 (AGS)/CdSeS core/shell QDs were prepared by a two-step synthetic approach.•CdSeS shell coating enabled largely improved visible optical properties of AGS QDs.•Ultrafast TA spectroscopy was used to uncover the detailed charge dynamics in QDs.•The core/shell QDs were successfully applied in PEC cells and photodetectors.