Synthesis of near-infrared-emitting type-II In(Zn)P/ZnTe (core/shell) quantum dots

Abstract

InP-based quantum dots (QDs) are considered promising candidates for replacing Cd-based QDs and ideal light emitters for next-generation displays. However, their spectral windows are confined to visible wavelengths, which restricts their applicability beyond displays. Thus, non-toxic colloidal QDs with the potential to extend the spectral window are highly desirable for many practical applications. Here, near infrared-emitting type-II In(Zn)P/ZnTe (core/shell) QD heterostructures are fabricated. As the ZnTe shell grows on an In(Zn)P QD core, the absorption band redshifts owing to the decreased optical band gap. Near infrared photoluminescent (PL) emission by type-II In(Zn)P/ZnTe (core/shell) QDs is realized by introducing an outer shell comprising ZnSeS passivation layers. The PL emission range of the resulting type-II In(Zn)P/ ZnTe/ZnSeS (core/shell/shell) QDs can be tuned by varying the In(Zn)P core diameter and ZnTe shell thickness. Meanwhile, the proposed QDs also exhibit a prolonged exciton lifetime of 387 ns indicates the type-II characteristics. Moreover, the ZnSeS passivation layers enable surface modification while preserving the optical and chemical stabilities, resulting in water-soluble QDs. Importantly, heavy-metal-free near infrared-emitting type-II In(Zn)P/ZnTe (core/shell) QDs have immense potential to increase the utilization of such materials in biomedical and energy applications requiring nontoxicity and near-infrared emission. (c) 2021 Elsevier B.V. All rights reserved.