Novel Au^I polyynes and their high optical power limiting performances both in solution and in prototype devices

Three novel Au^I polyynes have been prepared in high yield by copolymerization between an Au^I complex precursor and different ethynyl aromatic ligands. The investigation of their photophysical behavior has indicated that forming polyynes through polymerization not only maintains the high transparency of the corresponding Au^I polyynes similar to those of their corresponding small molecular Au^I acetylides, but also effectively enhances their triplet (T₁) emission ability. Critically, owing to their enhanced T₁ emission ability, all the Au^I polyynes exhibit a stronger optical power limiting (OPL) ability against a 532 nm laser than the corresponding small molecular Au^I acetylides. The Au^I polyynes based on fluorene and triphenylamine ligands show even better OPL performance than the state-of-the-art OPL material C₆₀, indicating their great potential in the field of laser protection. More importantly, in a prototype OPL device made by doping the fluorene-based Au^I polyyne into a polystyrene (PS) solid matrix, substantially improved OPL activity has been observed compared with that in the solution, demonstrating its great potential for practical application. All these results have provided a new strategy to achieve a balance between high OPL activity and good transparency for OPL materials, representing a valuable attempt towards developing new OPL materials with high performance to cope with the key problems in the field of nonlinear optics.