Controlling Nonlinear Optical Switch of Diarylethene by Changing Sizes of Fullerene: A Theoretical Study

Fullerene is a material with good electrical conductivity and thermal stability, and its size is an important factor to influence its photoelectric property. In this work, effect of fullerene size (C 20 , C 60 , and C 70 ) on nonlinear optical (NLO) switchable molecule diarylethene (DAE) was explored. In the aspect of molecular NLO properties, it could be found that the static first hyperpolarizability β tot of C x ‐O (x=20, 60, 70) was larger than that of C x ‐C (x=20, 60, 70), and the β tot difference between open‐ring and closed‐ring structure increased from 19 to 1431 au with the size of fullerene increased. Especially for C 70 ‐DAE, its largest contrast of β tot values between open‐ring and closed‐ring structure suggested its superiority among three groups of NLO switchable complexes. The result could attribute to C 70 ‐O exhibits a strong dipole characteristic, whereas C 70 ‐C displays a weak dipole characteristic. By analyzing dynamic first hyperpolarizability, it could be found large NLO response mainly depended on molecular dipole characteristics. As a result, for C 70 ‐DAE, β HRS of open‐ring structure was still larger than that of closed‐ring structure. However, the dynamic first hyperpolarizability β HRS of open‐ring structure was smaller than that of closed‐ring structure in both C 20 ‐DAE and C 60 ‐DAE. The switching efficiency was reversed.