Highly emissive 'frozen-in' conjugated polymer nanofibers.
Conjugated-polymer nanofibers with a thermodynamically stable, coarsened, disordered structure in an amorphous glassy state were fabricated via a freeze-drying method using a poly(diphenylacetylene) derivative. The nanofibers were extremely emissive, with a fluorescence (FL) quantum yield of approximately 0.34, which was much higher than that of both the cast film (0.02) and the solution (0.21). Similarly, the amplitude-weighted average FL lifetime of the nanofibers was 0.74 ns, which was much longer than that of the film (0.29 ns) and the solution (0.57 ns). This unusual and enhanced FL-emission behavior was attributed to the abruptly quenched chain structure that was created by the freeze-drying process. The polymer chains in the nanofibers remained frozen-in and the side phenyl rings were retained in a relaxed state. The metastable chains did not undergo vibrational relaxation and collisional quenching to generate the radiative emission decay effectively.
School of Applied Chemical Engineering, Major in Polymer Science and Engineering, Kyungpook National University 1370 Sankyuk-dong, Buk-ku, Daegu 702-701, Korea. gkwak@knu.ac.kr.
Young-Jae
YJ
Jin
Reliability Assessment Center for Chemical Materials, Korea Research Institute of Chemical Technology (KRICT), 141 Gajeong-ro, Yuseong-gu, Daejeon 305-600, Korea.
Wang-Eun
WE
Lee
Advanced Photonics Research Institute (APRI), Gwangju Institute of Science and Technology (GIST), 1 Oryong-dong, Buk-gu, Gwangju, Korea. vsepr@gist.ac.kr.
Chang-Lyoul
CL
Lee
School of Applied Chemical Engineering, Major in Polymer Science and Engineering, Kyungpook National University 1370 Sankyuk-dong, Buk-ku, Daegu 702-701, Korea. gkwak@knu.ac.kr.
Giseop
G
Kwak