The C=C photo-switching molecules (1,2-Di(4-pyridyl)ethylene (DPE), 4-styrylpyridine (SP) and trans-1,2-stilbene (TS)) show favorable photoisomerization characteristics. Although the solid states of photo-switching molecules are usually used in optical devices, their excited state’s evolution have been little explored. Here, the excited state’s relaxation of DPE, SP, and TS in nanocrystal/microcrystal suspensions as well as in solution phase were studied to uncover the early events of their excited states. The dynamics of nanocrystal/microcrystal suspensions was tremendously accelerated in comparison to the kinetics obtained in the solution for these molecules under excitation. DPE exhibits the slowest decay rate while SP shows the fastest decay rate whether in the nanocrystal suspensions or the solution, suggesting SP may be the best candidate unit for the photo-switching device. The intermolecular interactions and space restriction of crystal lead to the acceleration of excited state’s evolution for DPE, SP and TS. This provides new insight on the design of optical materials.
Excited state;nanocrystal;photo-switching;dynamics;transient absorption