Realization of high performance optical power limiting (OPL) materials by introducing OPL-active metal alkynyl segments into side chains of Pt(II) polyynes

To date, it is still a great challenge to realize high optical power limiting (OPL) ability with excellent visible light transmittance at the same time for organic OPL materials. For example, the carbazole-based Pt(II) polyynes usually showed good visible light transmittance but weak OPL ability. In this work, we designed and synthesized two high performance OPL materials by introducing OPL-active metal alkynyl segments into the side chain of carbazole-based Pt(II) polyynes for the first time. Arranging metal alkynyl in side chains could effectively disrupt the π-conjugation between the polymer backbones and side chains, thus the developed polymers showed excellent visible light transmittance. In addition, with more OPL-active metal alkynyl groups in the side chain, the developed polymers were expected to show good OPL performance at the same time. To further improve the OPL performance, we utilized the triphenylamine and triarylboron groups to manipulate the involvement of the Pt(II) center in transition processes, which could effectively influence the intersystem crossing to enhance the population of triplet states. As a result, the Pt(II) polyyne CzTPA with the triphenylamine group linked to OPL-active metal alkynyl groups in side chains displayed the best OPL performance with the figure of merit σ_ex/σ_o of up to 7.17, which was much higher than that of state-of-the-art OPL material C₆₀. Therefore, this work demonstrates a promising strategy to develop high performance OPL materials possessing both strong OPL ability and impressively high visible light transmittance at the same time.