Photoluminescence and Optical Gain Properties of a Crystalline Thiophene/Phenylene Co-oligomer

Abstract

We have successfully demonstrated a significant fluorescence property in an organic crystal made of a thiophene/phenylene co-oligomer called AC5. The crystal showed no non radiative transition, meaning it has 100% internal fluorescent quantum efficiency. The crystal also showed high quantum efficiency of photoluminescence of 23 AE 1%. Furthermore, it showed an amplified spontaneous emission at a threshold energy of 21.3 mJ/cm 2 and subsequently showed a quite high optical gain of 52.3 cm À1 . These features are attractive in many areas in the organic optics field such as organic light emitting diodes, organic lasers, and so on.

Evaluation of amplified spontaneous emission from photopumped thiophene/phenylene co-oligomers in polycrystalline states

“…The spectrum at approximately 485 nm finely showed the narrowed and strongest peak and end up increasing ten times larger than that around 520 nm. The narrowed fluorescence of the AC5 single crystal was also reported, and it indicated single peak profile at around 520 nm [17]. In our case, the peak around 520 nm became narrower, however, the other peak at 485 nm got stronger than 520 nm peak.…”

Current‐Injected Spectrally‐Narrowed Emissions from an Organic Transistor

“…Since many of the TPCO materials show the laser oscillation and the related SNEs in the form of a crystal,11 we expect those materials to serve the present research purpose. A reason for particularly choosing AC′7 is that a related alternating co‐oligomer 1,4‐bis(5‐phenylthiophen‐2‐yl)benzene (AC5)7 exhibits an exceedingly high luminescent quantum efficiency of nearly 100% 12. Both AC′7 and AC5 are characterized by that thiophenes and phenylenes (benzenes) are arranged alternately in the molecule.…”

Single Crystals of 5,5′‐Bis(4′‐methoxybiphenyl‐4‐yl)‐2,2′‐bithiophene for Organic Laser Media

“…Organic laser materials have been attracted much attention for photonic devices that can be integrated on a flexible substrate by low‐temperature processes using coating and vacuum deposition. Since the oscillation wavelength is tunable by molecular modification into different structures, organic materials can be designed as a laser medium with a high emission gain 1, 2. The regularly oriented molecules in organic crystals cause significant anisotropy in the optical and electronic properties resulting in polarized light emission and amplification.…”