Optically switchable photoluminescence using liquid-crystal dispersed quantum dots in film and capillary tube

An optically switchable photoluminence (PL) photonic material using azobenzene-doped cholesteric liquid crystal (CLC) -dispersed quantum dots (QDs) is demonstrated in the film and capillary tube, respectively. In the film, upon the light irradiation the trans-to-cis photoisomerization of azobenzene makes the QD-dispersed CLC cell highly transparent thus allowing most excitation photon to pass through the CLC cell and decreases the intensity of PL. In the capillary tube, there are two situations upon the light irradiation: the intensity of PL decreases when the irradiation applied on the PL excitation position; the intensity of PL increases when the irradiation applied ahead the PL excitation position. In view of the considerable interests in PL of QDs for photonic applications, our study on optically switchable PL from azobenzene doped CLC-dispersed QDs introduces a new approach of controlling emission of QDs by means of light. This may open the door to new exploitation for applications of QD such as light switchable, emission based liquid-crystal display (LCD) or optical communication device.