A Highly Crystalline and Wide-Bandgap Polydiarylfluorene with β‑Phase Conformation toward Stable Electroluminescence and Dual Amplified Spontaneous Emission

• Published in: ACS applied materials & interfaces 2016-08, Vol.8 (33), p.21648-21655
• Main Authors: Liu, Bin, Lin, Jinyi, Liu, Feng, Yu, Mengna, Zhang, Xinwen, Xia, Ruidong, Yang, Tao, Fang, Yueting, Xie, Linghai, Huang, Wei
• Format: Article
• Language: English
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.6b05247

Bulky conjugated polymers with high crystallinity is the prerequisite for the overall improvement of performance in wide-bandgap semiconductors, including charge transport, photoluminescence quantum yield, processing reliability, and stability. Herein, we report a stable β-phase film of bulky polydiarylfluorene (PODPF) preparing by thermal annealing at ∼220 °C. The β-phase conformation and regular molecular packing are confirmed by UV-vis, photoluminescence (PL), Raman spectra, and grazing incidence X-ray diffraction (GIXD), respectively. Polymer light-emitting diodes (PLEDs) with crystalline and β-phase film serving as the active layer exhibit higher current efficiency of 1.8 cd/A (6.0 V) and more stable electroluminescence over the amorphous one. Surprisingly, mixed conformations in PODPF film produce dually tunable amplified spontaneous emission (ASE) at 463 and 482 nm. Polydiarylfluorenes with quasi-planar conformation will be a promising candidate for the next-generation gain medium toward a broadly tunable lasing and dual-wavelength laser.