Deep‐blue, low‐threshold amplified spontaneous emitting and high thermal stability binaphthyl derivates

We have investigated the photoluminescent characteristics of binaphthyl derivates, 4,4-N,N-diphenylamine-4,4-diphenyl-1,1-binaphthyl (BN1), 4, 4-(9-(9H-9-carbazole)-4, 4-diphenyl-1, 1-binaphthyl (BN2) and 4, 4-bis(9-(p-fluorophenyl)-9H-3-carbazole))-1, 1-binaphthyl (BN3) and found their amplified spontaneous emission (ASE) from neat films. The ASE threshold of pumping energy, E-th=4.4, 3.8, 5.3 mu Jcm(-2) were obtained under optical excitation at 355nm for the neat films of BNs, 1, 2, and 3, respectively. Moreover, the lasing of those non-doped films exhibited deep-blue emission, whose peak spectra of BNs 1, 2, and 3 were 438, 421, and 428nm, respectively. We have also studied the thermal-stability of BN1 by annealing at 250 degrees C for 30min and found that the ASE threshold stayed almost unchanged compared to untreated film, demonstrating its high heat resistance characteristics. The characteristics of decreased tendency to crystallize and weaker intermolecular interactions in the solid state of BNs make them potential candidates for approaching electrically pumped organic laser diodes.