Presentation Information
[10a-A11-4]Excited-State Dynamics and Morphological Control of Donor-Acceptor-Donor Organic Laser Dye
〇(PC)Vishal Kumar1, Soh Kushida1, Takeru Inoue2, Keisuke Iwata2, Hiroshi Yamagishi1,3, Hayato Tsuji2, Yohei Yamamoto1,3,4 (1.Department of Materials Science, Institute of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573, Japan, 2.Department of Chemistry, Faculty of Science, Kanagawa University, 3-27-1 Rokkaku-bashi, Kanagawa-ku, Yokohama 221-8686, Japan, 3.Tsukuba Research Center for Energy Materials Science (TREMS), University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573, Japan, 4.Hydrogen Boride Research Center (HBRC), Tsukuba Institute for Advanced Research (TIAR), University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573, Japan)
Keywords:
WGM Laser,Organic Laser,Intramolecular Energy Transfer
Organic photonic devices require gain materials that simultaneously exhibit efficient excited-state dynamics, high optical gain, and controllable microstructural engineering. Here, we report a coplanar donor-acceptor-donor (D–A–D) molecule, COPV2-3-2, integrating carbon-bridged oligo(para-phenylenevinylene) donor and acceptor units through rigid orthogonal durylene bridges. This rational D–A–D design enables a four-level energy system that promotes efficient population inversion, large stimulated-emission cross-sections, and high optical gain. Femtosecond transient absorption and anisotropy studies reveal near-unity ultrafast intramolecular energy transfer (≈0.44 ps) with robust transition-dipole alignment. By modulating self-assembly through solvent microenvironment and kinetic control, COPV2-3-2 forms either anisotropic crystalline microrods or isotropic microspheres. The microrods function as active optical waveguides with low propagation losses (~0.07 dB μm-1), whereas the microspheres act as high-Q whispering-gallery-mode resonators exhibiting low-threshold lasing (~24 µJ cm-2). These results correlate sub-picosecond molecular photophysics and morphology-controlled photonic performance, highlighting COPV2-3-2 as a single-component organic gain material for integrated organic lasers, waveguides, and next-generation on-chip photonic devices.