Visible light mediated efficient photoswitching of dimethyldihydropyrenes in thin films for all-photonic logic gate applications and dynamic encryption/decryption capabilities†

Dimethyldihydropyrene (DHP) photoswitches exhibit visible light-induced ring-opening photoisomerization, reversed by UV light or heat. These photochromic systems exhibit extended half-lives, ranging from days to weeks for metastable photoisomers, making them applicable in diverse fields such as biology, optoelectronics, memory devices, and anti-counterfeiting measures. However, their solid-state photoswitching properties are suboptimal. To unlock their full potential for applications, the knowledge of solid-state switching is crucial. Solid-state photoswitching challenges are addressed in this study, investigating parent DHP and derivatives in polymer matrices. Self-aggregation and high optical density issues are mitigated by limiting the loading of the photochromic system below 2.5% (w/w), maintaining high solid-state photoswitching efficiency (85−90%). It was also found that the polymer rigidity enhanced the thermal stability of the open form. This study reveals that fusing aromatic rings enhances the photochromic efficiency of DHP systems, enabling both ring-opening and closing with visible light, and enhanced visible light reversal is observed with increased annelation. The optimized DHP-blended polymers also demonstrate possible applications of these systems as an all-photonic logic gate in the solid state, anti-counterfeiting and data storage, with dynamic encryption/decryption capabilities.