10:15 AM - 10:30 AM
▲ [13a-B11-6] Very Efficient Quasi-continuous-wave Lasing from Organic Semiconductor Films
Keywords:organic semiconductor films, Quasi-continuous-wave, Organic laser
The realization of efficient quasi-continuous-wave (qCW) lasing from organic semiconductor films under optical pumping is desired. In this sudy, we demonstrated efficient qCW lasing with reduced threshold (Eth) and increased repetition rate (f) by employing a doping technique, a mixed order grating (Fig. 1a), and a polymer overcoating film. The value of Eth obtained from a neat film of 4,4’-bis[(N-carbazole)styryl]biphenyl (BSBCz) embedded into a second-order grating was relatively high (Fig. 2b). Doping BSBCz into a host film of 4,4’-bis(N-carbazolyl)-1,1’-biphenyl (CBP) resulted in a reduction of Eth due to suppressed concentration quenching. The Eth was further reduced by replacing the second-order grating with a mixed order grating containing the second-order grating combined with a first-order grating. The qCW lasing at a very high f was difficult because of the ablation of the semiconductor film by strong excitation. To suppress the ablation, the semiconductor film was covered with a thick polymer film by spin coating. In this sample, we could realize a very high f of up to 80 MHz along with a very low Eth of 0.08−0.25 mJ cm−2, which is ten-fold higher than a previous record f of 8 MHz.1 These results would be useful for realizing reliable, cost-effective organic laser diodes in the future.