Upconverted circularly
polarized luminescence (UCPL) processes
have attracted great interest, because the chiroptical properties
could be expressed in different photophysical processes. In this Letter,
the first example of two-photon absorption-based upconverted circularly
polarized luminescence (TP-UCPL) is demonstrated. The chiral α-octylamine-modified
cesium lead bromides perovskite nanocrystals exhibited TP-UCPL with
a two-photon absorption cross section at 800 nm (σ2,800 nm) up to 3.68 × 104 GM and luminescence dissymmetric
factor (g
lum) up to 7.0 × 10–3. Depending on the molecular chirality of the capping
ligands, the TP-UCPL sense can be selected and the mirror-imaged CPL
is obtained. It is envisaged that this approach will afford a new
viewpoint for designing UCPL processes.
Long‐persistent circularly polarized phosphorescence (LPCPP) is achieved for the first time in chiral organic ionic crystals at room temperature. The co‐crystal composed of terephtalic acid (TPA) and chiral α‐phenylethyamines (PEAs) gave rise to LPCPP with lifetimes up to 862 ms and large dissymmetric factor (glum). The hybridization of TPA with chiral PEAs allows circular polarization of the generated long‐persistent phosphorescence. The observed mirror‐image twisted molecular structures in the rigid lattices were responsible for the chiroptical activation of the generated long‐persistent phosphorescence.
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