Highly efficient Zn:CuInSe2/ZnS quantum dots for near-infrared optical wireless communications

Abstract

Copper indium selenide (CISe) quantum dots (QDs), a class of narrow bandgap and environmentally friendly QDs, have been developed rapidly for application in the fields of biomedicine, solar cells, and telecommunications. However, synthesizing CISe QDs that emit beyond 800 nm while maintaining high photoluminescence quantum yields (PLQY) remains a significant challenge. Herein, we employed a hot injection solution method to synthesize high-quality core–shell structure Zn:CuInSe₂/ZnS QDs by adjusting the stoichiometric ratio of the CISe core and doping with Zn²⁺. The fabricated QDs exhibit a high PLQY of 62.7% at an emission wavelength of 810 nm with excellent photochemical stability and a large Stokes shift (150 nm). This can be attributed to pre-doping, which suppresses the cation exchange between Zn²⁺ and Cu⁺ or In³⁺ during the shelling process, and the passivation effects of ZnS on surface defects of the QDs. Furthermore, we demonstrate their application by using a home-built optical wireless communication (OWC) test platform, and the prepared QDs exhibit a modulation bandwidth of 3.23 MHz. With a bit error rate (BER) below the forward error correction (FEC) threshold of 0.0038, the system is capable of achieving a maximum data transmission rate of 14 Mbps. The synthesized high-efficiency PLQY Zn:CuInSe₂/ZnS QDs could be expected to promote the development of near-infrared (NIR) wireless communications.