Three-photon-induced singlet excited-state absorption for tunable ultrafast optical-limiting in distyrylbenzene: a first-principles study.

The ground and first singlet excited state absorption in distyrylbenzene (DSB) is simulated based on linear-response time dependent density functional theory (LR-TDDFT). It is found that distyrylbenzene shows a strong reverse saturable absorption effect around the near-infrared range. Combining the calculations of cubic response functions to simulate the three-photon absorption in distyrylbenzene, we are able to show that distyrylbenzene is a promising ultrafast optical limiter for the light with wavelengths around 775 nm. The primary mechanism for the optical limiting behavior can be well understood by the three-photon induced excited state absorption (3PA-ESA). This result in that DSB has high transmittance for low-intensity ambient light levels and the ultrafast response of optical-limiting. In addition, the limited optical window can be tuned by changing the length of the π-electron conjugated structure. It was also discovered that the molecular aggregation has an inhibitory effect on the optical limiting efficiency of distyrylbenzene. The present results may serve as a theoretical guideline for the design of distyrylbenzene-based optical limiting materials.