Low-Threshold Amplified Spontaneous Emission of Benzobisoxazole Derivatives in a Doped Film

In this study, we focus on benzobisoxazole (BOX) derivatives with the aim of achieving large stimulated emission cross sections, which are expected to contribute to lower laser thresholds and high stability. While both optically and electrically pumped organic semiconductor lasers have the potential to provide miniaturized lasers with wavelength tunability from ultraviolet to infrared, the development of organic semiconductors with low laser thresholds remains crucial for realizing stable devices. We report a low amplified spontaneous emission (ASE) threshold of BOX derivatives, which are doped into 4,4′-bis(carbazol-9-yl)biphenyl (CBP) host layers, with values as low as approximately 1 μJ/cm2. Further, we demonstrate high photostability under continuous photoexcitation, suggesting that BOX derivatives are promising candidates as emitting materials for organic semiconductor lasers (OSLs).