Synthesis and Assembly of Core-Shell Nanorods with High Quantum Yield and Linear Polarization

The seeded growth method offers an efficient way to design core-shell semiconductor nanocrystals in the liquid phase. The combination of seed and shell materials offers wide tunability of morphologies and photophysical properties. Also, semiconductor nanorods (NRs) exhibit unique polarized luminescence which can potentially break the theoretical limit of external quantum efficiency in light emitting diodes based on spherical quantum dots. Although rod-in-rod core-shell NRs present higher degree of polarization, most studies have focused on dot-in-rod core-shell NRs due to the difficulties in achieving uniform NR seeds. Here, this study prepares high-quality uniform CdSe NRs by improving the reactivity of the Se source, using a secondary phosphine, namely diphenylphosphine, to dissolve the Se power, along with the conventional tertiary phosphine, namely trioctylphosphine. Starting from these high-quality NR seeds, this study synthesizes CdSe/CdxZn1-xS/ZnS core-shell NRs with narrow emission bandwidth (29 nm at 620 nm), high PLQY (89%) and high linear polarization (p = 0.90). This study then assembles these core-shell NRs using the confined assembly method and fabricates long-range-ordered microarrays with programmable patterns and displaying highly polarized emission (p = 0.80). This study highlights the great potential of NRs for application in liquid crystal displays and full-color light emitting diodes displays.

Automated summary

The study prepares high-quality uniform CdSe nanorods by improving the reactivity of the Se source and using a secondary phosphine along with the conventional tertiary phosphine. Core-shell nanorods with narrow emission bandwidth, high PLQY, and high linear polarization are then synthesized and assembled into long-range-ordered microarrays with programmable patterns. The potential applications of these nanorods in liquid crystal displays and full-color light emitting diodes displays are highlighted.