Characterization of Gain-Narrowed Emission from Biphenyl-Capped Thiophene Single Crystals

Abstract

Photoluminescence spectral narrowing of 2,5-bis(4-biphenylyl)thiophene (BP1T) single crystals has been studied for various excitation lengths at 12 K to investigate the origin of its light amplification. In the range of excitation length L < 1:5 mm, the excitation energy threshold for the spectral narrowing of the 0 -1 vibronic transition band decreases with increasing excitation length. This behavior is not consistent with that of stimulated emissions. The present results give a plausible interpretation that a cooperative emission process contributes to the light amplification of the 0 -1 vibronic transition of the BP1T single crystals.

Cooperative Behaviors in Amplified Emission from Single Microcrystals of Thiophene/Phenylene Co‐Oligomers toward Organic Polariton Laser

“…Such unusual splitting spectra were also observed under the prethreshold excitation fluence even without F–P resonance at room temperature . Time‐resolved PL measurements of the single‐crystal TPCOs at low temperature revealed time‐profile changes from the spontaneous decay to the pulse‐shaped one with a delay of 50–70 ps with respect to the time origin of the excitation . Such a delay time is much longer than the rise time of the usual SE process since the vibrational relaxation of the excited state completes within sub‐picoseconds.…”

Optically pumped lasing from vapor‐grown crystals of methoxy‐substituted thiophene/phenylene co‐oligomer

“…1. Thin sword‐like crystals with well‐shaped parallel facets are obtained in contrast with irregular flake‐like morphology of other vapor‐grown TPCO crystals 20, 21. This well‐defined morphology of the BP1T‐OMe crystal may be ascribed to its orthorhombic structure in which the molecules are piled up in a direction perpendicular to the crystal plane.…”

Large gain for crystalline thin films of thiophene/phenylene co-oligomer by photopumping with femtosecond laser pulses

“…In most cases, reabsorption occurs in the fluorescence peak at the lower wavelength because the peak arises from the overlap between the absorption and emission. Matsuoka et al demonstrated that the fluorescence peak at around 465 nm in the fluorescence spectra of BP1T single crystals was closely related to reabsorption [14]. They measured the spectra at 12, 100, 200, and 300 K, and observed the peaks at 465 and 495 nm.…”