Optical properties of single crystals and vacuum-deposited thin films of a substituted oligo(p-phenylene vinylene)

Brouwer, Hendrik‐Jan; Krasnikov, V. V.; Pham, T. A.; Gill, Richard E.; Hutten, Paul F. van; Hadziioannou, Georges

doi:10.1016/s0301-0104(97)00215-2

Cited by 33 publications

(24 citation statements)

References 30 publications

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“…8 This advantage is due to the inherent long-range structural ordering of these single crystals. Furthermore, there are several examples of stimulated emission, including amplified spontaneous emission [9][10][11][12][13][14] ͑ASE͒, from molecular single crystals. These excellent photonic and electronic features imply the possibility of current-injection lasing.…”

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confidence: 99%

Photopumped laser oscillation and charge-injected luminescence from organic semiconductor single crystals of a thiophene/phenylene co-oligomer

Ichikawa

Nakamura

Inoue

et al. 2005

Applied Physics Letters

116

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We have demonstrated that single crystals of a thiophene/phenylene co-oligomer ͓␣ , -bis-biphenyl-4-yl-terthiophene ͑BP3T͔͒ show interesting photonic aspects: ͑1͒ the self-waveguided amplified spontaneous light emissions with a comparable low threshold of 8 J/cm 2 to other optimized organic solid-state laser systems, and ͑2͒ the laser oscillation based on the optical self-confinement effect in the crystals. We have also presented electroluminescence from the crystals based on bipolar injection and the crystals' tolerance for intense current driving. These achievements strongly imply that BP3T crystals are a promising candidate for organic laser diodes. © 2005 American Institute of Physics. ͓DOI: 10.1063/1.2138361͔The achievement of long-lasting, bright electroluminescence with high efficiency in both polymeric 1 and lowmolecular-weight organic materials 2 has inspired the development of a new class of laser diodes ͑LDs͒. Within this development, optically induced solid-state organic lasers have been proposed and fabricated based on thin films by methods such as solution casting and vacuum deposition with a wide range of related organic semiconductors. [3][4][5][6][7] As a counterpart of these research streams, crystalline molecular materials also get much attention as promising candidates for organic LDs demanding high-density electric pumping for population inversion. Organic molecular single crystals exhibit superior charge-carrier transport properties to amorphous and polymeric organic semiconductors.8 This advantage is due to the inherent long-range structural ordering of these single crystals. Furthermore, there are several examples of stimulated emission, including amplified spontaneous emission 9-14 ͑ASE͒, from molecular single crystals. These excellent photonic and electronic features imply the possibility of current-injection lasing. However, chargeinjected luminescence from organic single crystals with high stimulated emission properties has not yet been reported. We have achieved optically induced laser oscillation and chargeinjected luminescence from a molecular single crystal. This breakthrough opens up a new research path toward developing organic LDs.The synthesis of a thiophene/phenylene co-oligomer, ␣ , -bis-biphenyl-terthiophene ͑BP3T͒ used can be seen in our previous work. 15 The procedures of the crystal growth were also described in detail elsewhere. 16 The charged pressure of the N 2 +H 2 ͑10 mol %͒ growth gas was −18.6 kPa ͑a differential pressure from the atmosphere͒ at room temperature. The temperature of the growth cylinder was maintained at 360°C at the material-loaded position ͑bottom͒ and 300°C at the growth position ͑top͒ during crystal growth ͑about 150 h͒. The melting temperature of BP3T is 388°C. The source materials of the crystals were highly purified by sublimation in advance. A N 2 -gas laser that generated a light pulse of 500 ps duration at 337 nm was used as an excitation light source for the gain-narrowing experiment. The detailed experimental setup was described in our p...

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confidence: 99%

Photopumped laser oscillation and charge-injected luminescence from organic semiconductor single crystals of a thiophene/phenylene co-oligomer

Ichikawa

Nakamura

Inoue

et al. 2005

Applied Physics Letters

116

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“…10,11 In the present study, we investigate the temperature dependence of scaling aspects for Ooct-OPV5 oligomer thin films ͓Fig. 1͑a͔͒ 12,13 grown by vapor deposition onto Si substrates, held at temperatures in the range 20°C-100°C and fixed thickness dϭ100 nm. 14 During vacuum deposition, the molecules sublimate at ϳ230°C, and then, as a whole, condense onto the Si substrate.…”

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confidence: 99%

“…This value corresponds to the thickness of one molecular layer since it coincides with an earlier estimation for annealed Ooct-OPV5 films. 12,14 That was assumed to be the result of a particular molecular orientation, which was attributed to deformation due to adjustment of the c axis and/or the monoclinic angle. The high-temperature morphology of the Ooct-OPV5 film has to be seriously considered in optoelectronic device fabrication.…”

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confidence: 99%

Temperature dependence of the growth front roughening of oligomer films

Tsamouras

Palasantzas

2002

Applied Physics Letters

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Growth front roughening characteristics of vacuum deposited pentamer 2,5-di-n-octyloxy-1,4-bis[4-(styryl)styryl]-benzene oligomer thin films, onto silicon substrates, strongly depend on the substrate temperature in the range ∼20 °C–100 °C. The measured roughness exponents H increase from H≈0.4 at low substrate temperatures where growth is dominated by vacancy formation, to H≈0.7–0.8 at elevated temperatures where diffusive growth takes place. Moreover, the root-mean-square roughness amplitude and the correlation length evolve with temperature closely as an Arrhenius process with activation barrier comparable to molecule transnational and rotational barriers on oligomer surfaces.

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“…A good LED has to fulfil several preconditions: Injection efficiencies and charge mobilities for electrons and holes should be balanced, turnon voltage and current should be low, the probability for recombination of positive and negative charges should be high in the emitter zone and should lead to a high luminescence efficiency, the emission should produce a bright color at the desired wavelength and the materials of the device should be stable towards oxygen, water, light, etc. OPVs fulfil several but not all of these requirements, as numerous studies have revealed [19,20,22,44,81,87,[128][129][130].…”

Section: Applications In Materials Sciencementioning

confidence: 99%

Defined‐length Carbon‐rich Conjugated Oligomers

Meier

2006

Carbon‐Rich Compounds

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Optical properties of single crystals and vacuum-deposited thin films of a substituted oligo(p-phenylene vinylene)

Cited by 33 publications

References 30 publications

Photopumped laser oscillation and charge-injected luminescence from organic semiconductor single crystals of a thiophene/phenylene co-oligomer

Photopumped laser oscillation and charge-injected luminescence from organic semiconductor single crystals of a thiophene/phenylene co-oligomer

Temperature dependence of the growth front roughening of oligomer films

Defined‐length Carbon‐rich Conjugated Oligomers

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