This study presents an investigation of the excellent lasing performance of microlasers based on the combination of spherical polystyrene microresonators exhibiting Mie resonances of high Q‐factors, with two phenanthroimidazole derivatives as dopants, deep blue PI2PhDPO and sky‐blue BSBDPA, respectively. The latter are characterized by very high quantum yields, low nonlinear losses, such as reduced singlet‐triplet annihilation, and high photostability. Pumping various microresonators with a pulsed Nd:YAG laser at 355 nm we obtain a distribution of lasing thresholds with a median of 281 μJ cm −2 and very narrow lasing linewidths ( Q > 23 000) when using BSBDPA as a dopant. PI2PhDPO‐based microspheres, on the other hand, exhibit the lowest median lasing threshold of approximately 97 μJ cm −2 , demonstrating deep‐blue emission with an instrument‐limited Q factor greater than ≈25 000. The microlasers investigated here present a promising platform for realizing low‐threshold organic microlasers pumped by laser diodes, owing to their excellent gain properties and high‐Q optical cavities.
Mao et al. (Mon,) studied this question.