Solution-processed anthracene-based molecular glasses as stable blue-light-emission laser gain media

Two asymmetric 9,10-disubstituted anthracene-based, solution-processable, molecular glasses were studied in detail as thin-film laser gain media and were found to demonstrate very low amplified spontaneous emission (ASE) thresholds (0.75-1.1 μJ/pulse). Distributed feedback (DFB) lasers fabricated with these materials by spin coating on top of pre-etched silica one-dimensional (1-D) gratings exhibited a minimum laser threshold of 5.7 nJ per pulse (17.7 μJ cm-2) and maximum slope efficiency of 3.6%. The thermal stability of the gain was also investigated, with ASE observed for thermal annealing at temperatures up to 300 °C without any significant increase in threshold. The high thermal stability and low laser threshold make these materials very promising gain media. Comparison of the two glasses demonstrated that whilst fluorine-substitution significantly lowers the HOMO and LUMO levels it does not dramatically affect the gain. Our results suggest a potential approach for materials synthesis to address the challenge of electrically pumping an organic laser.