“…There is now a strong demand for efficient 2PA dyes for a wide range of applications, including microscopy [4,5,6,7,8,9,10,11,12,13], micro-fabrication [14,15,16], three-dimensional data-storage [17,18], up-converted lasing [19,20], and photodynamic therapy [21,22,23]. Recently, this demand has been matched by rapid advances in the design and synthesis of 2PA dyes [24,25,26,27,28,29,30,31,32,33,34].…”