Large-Stokes-Shifted Infrared-Emitting InAs–In(Zn)P–ZnSe–ZnS Giant-Shell Quantum Dots by One-Pot Continuous-Injection Synthesis

Infrared-emitting materials with a large Stokes shift and minimal reabsorption are technologically important for luminescent solar concentrators and for bioimaging applications. Here, we describe the synthesis of new InAs–In(Zn)P–ZnSe–ZnS quaternary giant-shell quantum dots that possess efficient photoluminescence in the near-infrared region. We employ a convenient one-pot, continuous-injection approach to achieve the controlled growth of thick In(Zn)P shells around small InAs nuclei. The In(Zn)P shell absorbs strongly across the visible spectrum from 400 to 780 nm and transfers the excitation to the InAs core for emission at 873 nm, hence providing a significant Stokes shift and minimal absorption–emission spectral overlap. Density functional theory calculations reveal a conduction band delocalization and a quasi-type-II band alignment that are responsible for the significant spectral red shifts during shell growth, despite a tiny core size of ca. 3 nm. The resulting quantum dots are neutral colored, contain no regulated heavy metals, and are broadly useful in consumer optoelectronic products and biological applications.