Modulation of Semiconductor Quantum Dot Photoluminescence by Photochromic Molecules

A hybrid system comprising semiconductor quantum dots (QDs) ligated with photochromic molecules has been synthesized and used to study the photomodulation of QD luminescence. The system has been constructed in such a way that the excited-state energies of the QDs and the molecules match but only for one of the conformations of the chromophore, thus enabling phototunable energy transfer from the QD to the ligands. Furthermore, the hybrid system can be immobilized in thin polymer films, creating a solid-state optical switching device. It is demonstrated that the switching of QD photoluminescence between the high-emissive and quenched states occurs on a time scale of tens of milliseconds and in some cases takes even less than 10 ms. The red-green-blue color space can be covered by using three different types of QDs while employing only a single type of photochromic molecule.