Pressure-Responsive Multicolor Emission in Cd ₃ P ₂ /ZnSe Core/Shell Quantum Dots: Comparative Effects of Interfacial Strain vs External Pressure

Core/shell quantum dots (QDs) have emerged as a promising class of light-harvesting materials for solar energy conversion due to their highly tunable optical properties. Most studies have focused on II–VI, III–V, and I–III–VI group QDs. Herein, we synthesized a series of thick-shell ZnSe-coated II–V group Cd3P2 QDs. The emission spectra of Cd3P2/ZnSe QDs exhibit a substantial blue shift with increasing shell thickness. Moreover, these emission spectra further blue-shift under pressure and exhibit pressure-tunable multicolor luminescence. It is noteworthy that the photoluminescence (PL) peak position of Cd3P2/ZnSe shifted by 21 nm after coating the first 2.5 nm thick shell. Another 2.6 nm thick shell further shifted the PL peak position by 10 nm. In contrast to the emission induced by the interfacial chemical pressure, the Cd3P2/ZnSe QDs required a 2.0 GPa external physical pressure to reach the same wavelength. However, another 10 nm offset only corresponds to a pressure of 1.0 GPa. These results indicate that interfacial chemical pressure affects PL emission in Cd3P2-based QDs less effectively than external physical pressure. This work provides significant insights into interfacial strain and external pressure effects on optical properties in Cd3P2/ZnSe core–shell QDs, advancing the understanding of core–shell nanomaterials.