Colloidal ZnTe Quantum Dots for Potential Heavy-Metal-Free Emitters

Colloidal ZnTe quantum dots (QDs) are promising cadmium-free emitters for blue and green spectral regions. However, the lack of effective synthetic strategies to produce high-quality ZnTe QDs with tunable sizes has hindered their applications. To address this challenge, a seeded growth method was developed to synthesize colloidal ZnTe QDs (1.7–9.9 nm) with tunable fluorescence emission from 424 to 520 nm. Furthermore, growing thick ZnSe shells on large-sized ZnTe QDs (9.9 nm) extended the fluorescence emission to the red region (625 nm), broadening their spectral coverage. Thin ZnSeTe/ZnSe shells were designed and deposited onto large-sized ZnTe QDs (9.9 nm), forming Type-I ZnTe/ZnSeTe/ZnSe core/shell/shell nanostructures. These nanostructures exhibited improved stability, a narrow full width at half-maximum (fwhm) of 25 nm, and a photoluminescence quantum yield (PLQY) of 45%. The successful production of these high-quality ZnTe QDs provides a novel, heavy-metal-free alternative for emitters across the full visible spectrum.