Synergistic tailoring of band structure and charge carrier extraction in “green” core/shell quantum dots for highly efficient solar energy conversion

Abstract

Environment-friendly colloidal core/shell quantum dots (QDs) with controllable optoelectronic characteristics are promising building blocks for future commercial solar technologies. Herein, we synergistically tailor the electronic band structure and charge carrier extraction of eco-friendly AgInS2 (AIS)/ZnS core/shell QDs via Mn-alloying and Cu-doping in the core and shell, respectively. It is demonstrated that the Mn-alloying in AIS core can broaden the band gap to facilitate delocalization of photogenerated electrons into the shell and further incorporation of Cu in the ZnS shell enables the creation of Cu-related states that capture the photogenerated holes from core, thus leading to charge carrier recombination and accelerated transfer of photogenerated electrons in the core/shell QDs. As-prepared Mn-AIS/ZnS@Cu QDs were assembled as light harvesters in a photoelectrochemical (PEC) device for light-driven hydrogen evolution, delivering a maximum photocurrent density of ∼ 6.4 mA cm−2 with superior device stability under standard one sun irradiation (AM 1.5G, 100 mW cm−2). Our findings highlight that simultaneously engineering the band alignment and charge carrier dynamics of “green” core/shell QDs endow the feasibility to design future high-efficiency and durable solar hydrogen production systems.