Polarized laser oscillation from polygon crystals of thiophene/phenylene co‐oligomers grown by liquid‐phase growth

Abstract

We have investigated the laser oscillation and its polarization feature of a thin polygon crystal of a thiophene/phenylene co‐oligomer grown by the novel liquid‐phase method. The emission spectrum from the crystal ca ‐plane (along the b‐axis) narrows with increasing energy of the pulsed laser excitation, which is incident perpendicularly to the crystal plane (the ab ‐plane). The multi‐mode laser oscillation was observed around 515 nm with the excitation over 5 mJ/cm2 per pulse. A mode separation and a full width at half maximum of the peak were estimated to be ∼0.2 nm and ∼65–85 pm, respectively. The laser emission was confirmed to be strongly polarized along the c‐axis. Its polarization ratio of the c‐axis to the a‐axis was estimated to be ∼550. This large ratio is due to the upright configuration of the molecular long axis that is almost perpendicular to the ab‐plane. These results indicate that the present polygon thin crystal is suitable for laser device application. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Green light emission from the edges of organic single-crystal transistors

“…We investigated the optical properties of our AC5 single crystals. As previously reported, single crystals of AC5 have optical confinement and self-waveguiding effects, 17,21,22 which are considered to partially account for their good light amplification properties. Our AC5 crystals also showed this reported light emission behavior.…”

“…The single crystals of AC5 are characterized by good transport and outstanding optical properties, including laser oscillation and highly polarized emissions. [16][17][18][19][20][21][22][23][24] Most importantly, the reported internal fluorescent quantum efficiency of AC5 is extremely high ͑74% in solution and 100% as a single crystal͒. 25,26 The pho-toluminescent light is naturally confined within crystals and only the crystal fringes are strongly luminescent ͓Fig.…”

Optically and electrically excited emissions from organic semiconducting oligomer crystals

“…After these achievements many organic semiconductors including TPCOs were reported to exhibit laser oscillation in the form of a single crystal . Peculiar crystallographic structures of TPCOs are responsible for it .…”

Refractive Index Measurements of Well-Defined Polygon Crystals of Thiophene/Phenylene Co-Oligomers

“…Since organic semiconductor crystals exhibit large carrier mobilities [1][2][3][4] and peculiar optical features, e.g., spectrally narrowed emission (SNE) [5][6][7] and laser oscillation, [8][9][10][11][12][13][14] these crystals are expected to play a central role in organic optoelectronic devices in the near future. To ensure this, various physical constants will have to be measured and determined precisely.…”