Heterogeneous photoswitching kinetics of diarylethenes and their effect on localization microscopy resolution

Diarylethenes (DAE) have recently been used as effective fluorescent probes for single-molecule super-resolution imaging of soft materials owing to their ability to switch between an emissive and dark state multiple times via an intramolecular photocylization reaction. However, these dyes display a broad distribution in the number of times each molecule switches and in the lifetime of each state, which can negatively impact the ultimate resolution of an image. In this work, we characterize the heterogenous switching behavior of a DAE derivative and examine its effect on image resolution. Complementary cumulative distribution functions reveal broad lifetime distributions of the emissive and dark states, spanning multiple decades for both individual molecules and large ensembles. The emissive state lifetime distributions can be described by a power law, while the dark state lifetime distributions display two distinct regions, which can be fit to a weighted sum of a stretched exponential function and a power law, suggesting there is more than one dark state. Fits of these distributions were used to simulate super resolution experiments in various polymers to investigate the impact on image resolution due to heterogenous photoswitching kinetics.