A novel two-branched twistacene (PyDN) has been designed and synthesized for application on ultrafast optical limiting. This twistacene exhibits excellent two photon absorption and two photon absorption-induced excited singlet state absorption, which was systematically investigated with a femtosecond Z-scan experiment, transient absorption spectrum, and two-photon excited fluorescence experiments. The admirable two photon absorption is attributed to the high degree of π electron delocalization in twistacene which is caused by introduction of two strong donors. The excited singlet state absorption cooperates with two-photon absorption to provide an excellent ultrafast optical limiting behavior with high linear transmittance, where the thresholds are 2.3–5.3 mJ/cm² in the spectral region of 532–800 nm of femtosecond laser and 133 mJ/cm² for picosecond pulse at 532 nm. These thresholds are lower than that of most of the optical limiters reported previously, which indicates PyDN is a promising candidate for ultrafast optical limiting.

In the red region (650–800 nm), the nonlinear absorption of trithiophene-based compound INT3 is greater than that of triphenylamine-based compound INB3, while in the NIR region (800–1100 nm), the strength of nonlinear absorption is the opposite.

The explosive growth of data and information has increasingly motivated scientific and technological endeavors toward ultra-high-density data storage (UHDDS) applications. Herein, a donor−acceptor (D–A) type small conjugated molecule containing benzothiadiazole (BT) is prepared (NIBTCN), which demonstrates multilevel resistive memory behavior and holds considerable promise for implementing the target of UHDDS. The as-prepared device presents distinct current ratios of 10^5.2/10^3.2/1, low threshold voltages of −1.90 V and −3.85 V, and satisfactory reproducibility beyond 60%, which suggests reliable device performance. This work represents a favorable step toward further development of highly-efficient D–A molecular systems, which opens more opportunities for achieving high performance multilevel memory materials and devices.