Since the discovery of the first laser in 1960, wide varieties of applications have been found, including fundamental usage such as scientific optical excitation and photolithography, industrial laser cutting, drilling, military applications, medical imaging and surgery. The key advantages of using organic semiconductors are low cost, light weight and high flexibility.1 A solid-state optically pumped organic laser was first demonstrated about two decades ago2 while an electrically pumped organic laser (i.e. using direct electrical pump) is still to be realised.
The key challenges for electrically pumped organic lasers include finding suitable materials with high photoluminescence and low losses like self-absorption as well as designing appropriate device architectures to achieve high current density and high brightness as well as low gain losses associated with polarons and electrodes.3,4 In this work, we report our investigation of an organic fluorescent chromophore for its potential as an organic laser dye. New synthetic route to the chromophore will be reported. Its low amplified spontaneous emission (ASE) threshold of 21 mJ/cm2 in solution, comparable to a common commercial laser dye, Rhodamine 6G, will be discussed. Notably, the material had the lowest solid-state ASE threshold (2.4 μJ/cm2) for similar classes of organic laser dyes prepared from solution. In this report, organic light-emitting diode performance based on the dye with a maximum external quantum efficiency of 1.9% will also be presented to show its potential toward the realisation of organic laser diodes.
1. I. D. W. Samuel, Laser Physics: Fantastic Plastic. Nature 2004, 429, 709-711.
2. F. Hide, M. A. Diaz-Garcia, B. J. Schwartz, Semiconducting Polymers: A New Class of Solid-State Laser Materials. Science 1996, 273, 1833-1836.
3. I. D. W. Samuel, G. Turnbull, Organic Semiconductor Lasers. Chemical Reviews 2007, 107, 1272-1295.
4. K. Hayashi, H. Nakanotani, M. Inoue, K. Yoshida, O. Mikhnenko, T.-Q. Nguyen, C. Adachi, Suppression of Roll-Off Characteristics of Organic Light-Emitting Diodes by Narrowing Current Injection/Transport Area to 50 nm. Applied Physics Letters 2015, 106, 093301(1)-093301(5).