An efficient all-visible light-activated photoswitch based on diarylethenes and CdS quantum dots.

All-visible light-activated diarylethene (DAE) photoswitches are highly attractive for applications in smart photoresponsive materials. The photocyclization of DAE the low-lying excited triplet state through triplet energy transfer (TET) from a sensitizer has been proven to be an effective approach for the realization of this scheme. However, the TET process is sensitive to oxygen and typically requires more than one sensitizer per photoswitch to facilitate sensitized photocyclization. Herein, we present a bi-component system comprising carboxylic acid-functionalized DAEs and CdS quantum dots (QDs) to achieve all-visible light-activated photoswitching. Due to the large surface area-to-volume ratio of CdS QDs and surface anchored DAEs, one CdS QD can activate at least 18 DAE molecules in the solution without oxygen exclusion. The efficiency of photocyclization of DAEs under visible light irradiation through energy transfer from CdS QDs is nearly comparable to that of direct UV light irradiation. Moreover, our strategy is adaptable for solid-state applications in the presence of air, enabling reversible writing and erasing of color and patterns by adjusting irradiation wavelengths in the visible region.