Improved optical limiting of triazine-linked mono-, bis- and tris-phthalocyanines Quan Miao, Zhaoyang Sang, Rengang Song, Min Liang, Erping Sun and Yan Xu Eur. Phys. J. D, 73 2 (2019) 35 Published online: 12 February 2019 DOI: 10.1140/epjd/e2019-90577-2