[15a-302-1~10] 12.4 Organic light-emitting devices and organic transistors

▲ [15a-302-5] Continuous-wave lasing from organic semiconductor films

〇(P)SANGARANGE DONATULA SANDANAYAKA^1,2, T. Matsushima^1,2,3, F. Bencheikh^1,2, K. Yoshida¹, M. Inoue¹, T. Fujihara⁴, K. Goushi^1,2, J.-C. Ribierre^1,2, C. Adachi^1,2,3 (1.OPERA, Kyushu Univ., 2.JST/ERATO, 3.I2CNER, Kyushu Univ., 4.ISIT)

Keywords:Organic semiconductor films, Continuous-wave, Organic laser

In this study, quasi-continuous-wave (quasi-CW) and true-CW photoexcitation surface- emitting lasing are demonstrated in a distributed feedback device which combines a mixed-order grating with an organic thin film of a host material 4,4’-bis(N-carbazolyl) -1,1’-biphenyl (CBP) blended with an organic laser dye 4,4’-bis[(N-carbazole)styryl] biphenyl (BSBCz).^1,2 The quasi-CW laser operation maintained up to a repetition rate of 80 MHz (Fig. 1a). Additionally, the true-CW laser operation was demonstrated even under 30 ms of long photoexcitation (Fig. 1b). This outstanding performance was achieved using a BSBCz:CBP blend film with high optical gain, high photoluminescence quantum yield and no triplet absorption losses² at the lasing wavelength along with a mixed-order distributed feedback grating to achieve low lasing threshold. Simple encapsulation of devices with CYTOP was a key method used to greatly reduce the laser-induced thermal degradation and suppress the ablation of the gain medium taking place under intense CW photoexcitation. The influence of pump pulse widths and the role of the CYTOP encapsulation were analyzed on the basis of thermal and optical simulation results. Overall, this study provides evidence that the development of true-CW organic semiconductor laser technology is possible via the engineering of the gain medium and the device architecture.