Light-induced luminescence quenching in precursor-route poly(p-phenylene vinylene)

Bradley, Donal D. C.; Friend, Richard H.

doi:10.1088/0953-8984/1/23/011

Cited by 107 publications

(41 citation statements)

References 17 publications

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“…The pressure dependence of E g1 , while similar in shape for the three sequences, is nonreversible between these sequences. The red-shift in the PL peak energy is consistent with a reduction in the HOMO-LUMO gap observed in conjugated polymers and in the oligomerization of organics [15,16]. Our vE g /vP values are also in reasonable agreement with K80, K25 and K11 meV/GPa observed for pristine C 60 , 2D-rhombohedral and 2D-tetragonal phases of HPHT C 60 , respectively, [7].…”

Section: Photoluminescence Spectrasupporting

confidence: 89%

New features in the pressure dependence of photoluminescence spectra of C60 at room temperature

Sharma

Sing

2005

Solid State Communications

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Section: Photoluminescence Spectrasupporting

confidence: 89%

New features in the pressure dependence of photoluminescence spectra of C60 at room temperature

Sharma

Sing

2005

Solid State Communications

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“…The excitons formed by photo-excitation or under electric field go through various pathways such as radiative or non-radiative decays and charge separation, etc. [22,23] From our poor LED device results, we thought of a possibility to prevent an exciton formation through an electron capture of the electron withdrawing octafluorobiphenyl units that are isolated from the EL emitting chromophore by the ether linkage. If an electron from the cathode is captured by the octafluorobiphenyl unit, the exciton formation, i.e., a hole-electron collision can be hindered through isolation of the electron from the hole in the chromophore.…”

Section: Electroluminescent Device Propertymentioning

confidence: 99%

Synthesis and Luminescent Properties of Blue Light Emitting Polymers Containing both Hole and Electron Transporting Units

Ahn

Shim²

2001

Macromol. Chem. Phys.

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Poly[(oxy‐4,4′‐octafluorobiphenyloxy)‐1,4‐phenylenevinylene‐2‐methoxy‐5‐(2‐ethylhexyloxy)‐1,4‐phenylenevinylene‐1,4‐phenylene], POFB‐MEH‐PPV, poly[(oxy‐4,4′‐octafluorobiphenyloxy)‐1,4‐phenylenevinylene‐9,9‐dihexyl‐2,7‐fluorenediylvinylene‐1,4‐phenylene], POFB‐PF, and poly[(oxy‐4,4′‐octafluorobiphenyloxy)‐1,4‐phenylenevinylene‐N‐ethylhexyl‐3,6‐carbazolevinylene‐1,4‐phenylene], POFB‐PK, were synthesized by the well‐known Wittig condensation polymerization. We incorporated the high electron affinity (octafluorobiphenyl) and hole‐transporting (carbazole, fluorene, and dialkoxyphenyl) units into the conjugated main chain. The conjugation lengths are limited to the blue‐emission region by ether linkage. The resulting polymers were completely soluble in common organic solvents such as chloroform, 1,2‐dichloroethane, and cyclohexanone, and exhibited good thermal stability up to 300°C. The synthesized polymers showed UV‐visible absorbance and photoluminescence (PL) in the ranges of 350–385 nm and 460–490 nm, respectively. The fluorene or carbazole containing POFB‐PF and POFB‐PK showed blue photoluminescence peaks at 470 and 460 nm, respectively. The single‐layer light‐emitting diode was fabricated in a configuration of ITO (indium‐tin oxide)/polymer/Al. Electroluminescence (EL) emission of POFB‐PF and POFB‐PK were shown at 475 and 458 nm, respectively, corresponding to the pure blue emissions. And, a dialkoxyphenyl containing POFB‐MEH‐PPV showed greenish blue light at 494 nm. But, LED devices from synthesized polymers showed poor device performance and high turn on voltage. So, we fabricated light‐emitting diodes (LEDs) from blend polymers composed of poly[2‐methoxy‐5‐(2‐ethylhexyloxy)‐1,4‐phenylenevinylene] (MEH‐PPV) and POFB‐MEH‐PPV (POFB‐PF or POFB‐PK) as the emitting layers. The EL emission maxima of each blend polymers were in the range of 573–591 nm, which indicates that the emission is mainly due to MEH‐PPV and POFB‐MEH‐PPV (POFB‐PF or POFB‐PK) contributes to the enhancement of the luminescence. And each blend polymers exhibited higher EL quantum efficiency compared with MEH‐PPV at the same current density.

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“…It has only been suggested that mobile SE's ͑Ref. 11͒ are nonradiatively quenched by polarons, 12 similar to quenching by defects such as carbonyl groups. 13 In contrast to molecular crystals such as para-hexaphenyl, 14 conjugated polymers exhibit strong polaronic photoinduced absorption ͑PA͒ bands, 9,15 so there is a need to quantify the interaction of polarons and SE's.…”

Section: Introductionmentioning

confidence: 99%

Interaction of singlet excitons with polarons in wide band-gap organic semiconductors: A quantitative study

et al. 2001

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The steady-state photoinduced absorption ͑PA͒, photoluminescence ͑PL͒, PL-detected magnetic resonance ͑PLDMR͒, and PA-detected magnetic resonance ͑PADMR͒ of poly-and oligo-͑para-phenylenes͒ films is described. In particular, the excitation density ͑laser power͒ N 0 dependence of the PA, PL, and PLDMR signals is analyzed by means of a rate equation model, which describes the dynamics of singlet excitons ͑SE's͒ and polarons in all three experiments quantitatively with the same set of parameters. The model is based on the observations that mobile SE's are quenched by trapped and free polarons and that the spin-1 2 magnetic resonance conditions reduce the total polaron population. Since the sublinear N 0 dependences of the positive ͑PL-enhancing͒ spin-1 2 PLDMR and the polaron PA band are essentially the same, we conclude that PLDMR is due to a reduced quenching of SE's by polarons. The agreement between the model, the current results, and results from other spectroscopic techniques provides strong evidence for this quenching mechanism. This also suggests that it is a very significant process in luminescent -conjugated materials and organic light-emitting devices. Consequently, the quenching mechanism needs to be taken into account, especially at high excitation densities, which is of great importance for the development of electrically pumped polymer laser diode structures.

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Light-induced luminescence quenching in precursor-route poly(p-phenylene vinylene)

Cited by 107 publications

References 17 publications

New features in the pressure dependence of photoluminescence spectra of C60 at room temperature

New features in the pressure dependence of photoluminescence spectra of C60 at room temperature

Synthesis and Luminescent Properties of Blue Light Emitting Polymers Containing both Hole and Electron Transporting Units

Interaction of singlet excitons with polarons in wide band-gap organic semiconductors: A quantitative study

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