Carbon
quantum dots (CQDs) have been extensively explored in diverse
fields because of their exceptional features. The nanometric particles
with photoluminescence (PL) benefit various optical and photonic applications.
However, the majority of previous reports have mainly focused on either
unpolarized or circular-polarized (CP) PL. Linearly polarized (LP)
emission of CQDs is limited mainly because of their isometric shape
and difficulties in macroscopic orientation control. Herein, we report
syntheses of anisometric CQDs and facile control of the uniaxial orientation
on a macroscopic scale, which results in linearly polarized photoluminescence
(LP-PL). The anisometric CQDs are synthesized from rigid-rod-shaped
precursors and evenly dispersed in the rod-like liquid crystal (LC)
host. As-synthesized CQDs exhibit a PL quantum yield as high as 35%
in chloroform. In addition to uniform alignment, facile directional
switching of the elongated CQD is established by employing the electrical
responsiveness of the CQD and host LC. Therefore, the dichroic photophysical
properties of anisometric CQDs have been beneficially adopted for
fabrications of polarization-sensitive and electrically switchable
PL devices. Also, anisometric CQDs are embedded in polymer films with
molecular orientational patterns and clearly recognized by LP-PL.
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