posted on 2024-04-03, 19:18authored byTakumi Matsuo, Shotaro Hayashi
Low-dimensional structures are ideal for organic laser
media because
of their efficient waveguide, photon confinement, and stimulated emission.
Control of the structure and alignment of luminescent molecules is
very important for realizing laser media. Here, we fabricate low-dimensional
crystals of bis(biphenyl)fumaronitrile (BPFN), which is an aggregation-induced
emission luminogen. The BPFN molecule contains fumaronitrile, which
displays solid-state luminescence, and biphenyl, which forms low-dimensional
structures through dipole–dipole interactions. Solvent diffusion
yielded two-dimensional platelet crystals of BPFN with strong dipole–dipole
CH−π interactions. The high photoluminescence quantum
efficiency of 0.46 and uniaxially aligned molecular π-electronic
transition dipole moment in the two-dimensional crystals of BPFN resulted
in optically pumped lasing even when using an optical excitation source
with a long pulse duration (∼5 ns). One-dimensional BPFN crystals
obtained via epitaxial growth on the cleaved surface of a KBr single
crystal also displayed lasing behavior.