Enhanced optical limiting properties of composite films consisting of hyperbranched phthalocyanine and polyphenylsulfone with high linear transmittance

At present, the extensive research on laser protective materials is mainly focused on ensuring the linear transmittance and improving the optical limiting ability. Phthalocyanine has become a promising optical limiting material because of its special large π electronic conjugated structure, which makes it has excellent nonlinear optical properties and fast optical-electron response. Here, we synthesized a sulfonyl-containing hyperbranched lanthanum phthalocyanine (HLaPc) and covalently linked the anthraquinone groups (HLaPc-HAQ) in its axial direction. Since a donor-acceptor system is formed between phthalocyanine and the anthraquinone in HLaPc-HAQ, the electron transfers can effectively enhance the nonlinear optical properties of HLaPc-HAQ. According to the “like dissolves like” theory, two kinds of homogeneous films have been obtained by blending HLaPc and HLaPc-HAQ with yellow polyphenylene sulfoxide containing anthraquinone groups (YPPSU). The films obtained by solution casting method have high transmittance and excellent optical limiting properties. Especially, the Z-scan results show that the lowest incident intensity threshold (I lim ) of HLaPc-HAQ/YPPSU can reach 0.012 J cm -2 , and the linear transmittance can still maintain above 57%. This means that the materials obtained in this work surpassed much previously reported work in terms of comprehensive linear transmittance and optical limiting performance. In addition, the energy level model was drawn by the results of the cyclic voltammogram of the solution and the solid films. And from the perspective of the energy level transition, it was confirmed that there are a larger proportion of molecules in the solid films for intersystem crossing, thereby improving optical limiting performance.