Triplet excimer formation of triphenylamine and related chromophores in polystyrene films

Burkhart, Richard D.; Jhon, Nam In

doi:10.1021/j100172a019

Cited by 30 publications

(33 citation statements)

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“…However, the majority of their data is convoluted with m‐MTDATA excimer emission, and is very likely that the estimated 50 meV activation energy is in fact dominated by the energy barrier of excimer formation. For example, Burkhart et al found that triphenylamine related excimers have activation energy of very similar magnitude …”

Section: Resultsmentioning

confidence: 99%

Photophysical Investigation of the Thermally Activated Delayed Emission from Films of m‐MTDATA:PBD Exciplex

Graves

Jankus

Dias

et al. 2013

Adv Funct Materials

149

138

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Understanding the delayed fl uorescence mechanism behind the creation of emissive singlets from the non-emissive triplets in exciplexes is vital for the fabrication of highly effi cient blue fl uorescent emitters, and subsequent white light applications. In this article we report the spectroscopic investigation of the exciplex formed between 4,4′,4′′-tris[3-methylphenyl(phenyl)amino] triphenylamine (m-MTDATA) and 2-(biphenyl-4-yl)-5-(4-tert-butylphenyl)-1,3,4oxadiazole (PBD) in a 50:50 blended fi lm. The mechanism behind extra singlet production in the blend is of E-type nature, that is, "thermally activated" delayed fl uorescence. The exciplex singlet-triplet energy splitting is estimated to be around 5 meV, smaller than previously estimated at ≈50 meV. The absence of a well defi ned separation between prompt emission and emission components with very long lifetimes, >100 ns, is indicative of such a small exchange energy, and arises through multiple cycling between the resonant singlet and triplet manifolds before eventually being emitted from a singlet state. An observed redshift of the exciplex emission with time and increasing temperature is attributed to different exciplex species being formed between the m-MTDATA and PBD molecules.

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Section: Resultsmentioning

confidence: 99%

Photophysical Investigation of the Thermally Activated Delayed Emission from Films of m‐MTDATA:PBD Exciplex

Graves

Jankus

Dias

et al. 2013

Adv Funct Materials

149

138

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“…Indeed, POAPF possesses four important characteristics: i) a high value of E T because of the complete isolation of the p-electrons of the triphenylamine (E T ¼ca. 3.04 eV) [35] and 2,7-bis(diphenylphosphoryl)fluorene units (E T ¼ca. 2.72 eV, estimated from the methyl-substituted analogue) [27] provided by the nonconjugated linkage; ii) bipolarity, resulting from the coexistence of p-and n-type groups; iii) appropriate HOMO/LUMO energy levels, originating from the presence of electron-donating and accepting building blocks within the molecule; and iv) the capability of forming a stable amorphous thin film as a result of the molecule's bulky, nonplanar structure.…”

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confidence: 99%

A Bipolar Host Material Containing Triphenylamine and Diphenylphosphoryl‐Substituted Fluorene Units for Highly Efficient Blue Electrophosphorescence

Hsu

Chien

Shu

et al. 2009

Adv Funct Materials

198

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Highly efficient blue electrophosphorescent organic light‐emitting diodes incorporating a bipolar host, 2,7‐bis(diphenylphosphoryl)‐9‐[4‐(N,N‐diphenylamino)phenyl]‐9‐phenylfluorene (POAPF), doped with a conventional blue triplet emitter, iridium(III) bis[(4,6‐difluoro‐phenyl)pyridinato‐N,C2´]picolinate (FIrpic) are fabricated. The molecular architecture of POAPF features an electron‐donating (p‐type) triphenylamine group and an electron‐accepting (n‐type) 2,7‐bis(diphenyl‐phosphoryl)fluorene segment linked through the sp3‐hybridized C9 position of the fluorene unit. The lack of conjugation between these p‐ and n‐type groups endows POAPF with a triplet energy gap (ET) of 2.75 eV, which is sufficiently high to confine the triplet excitons on the blue‐emitting guest. In addition, the built‐in bipolar functionality facilitates both electron and hole injection. As a result, a POAPF‐based device doped with 7 wt% FIrpic exhibits a very low turn‐on voltage (2.5 V) and high electroluminescence efficiencies (20.6% and 36.7 lm W−1). Even at the practical brightnesses of 100 and 1000 cd m−2, the efficiencies remain high (20.2%/33.8 lm W−1 and 18.8%/24.3 lm W−1, respectively), making POAPF a promising material for use in low‐power‐consumption devices for next‐generation flat‐panel displays and light sources.

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“…For the unipolar polymers, the phosphorescence spectrum of Si(doTPA) with the peaks at 465(sh), 493 and 533(sh) nm and that of Si(dtOXD) with the peaks at 468, 503 and 533(sh) nm are quite similar to that of Si(dBu). Also, for the unipolar polymers, by enlarging the spectra in the range 390–450 nm, a peak of Si(doTPA) at 405 nm and two weak peaks of Si(dtOXD) at 416 and 446 nm are observed, which are nearly identical to their corresponding isolated TPA at 405 nm and OXD at 414 and 446 nm2526, indicating that the occurrence of triplet energy transfer from the side arm TPA or OXD moieties to the backbone silylene-diphenylene is efficient but still incomplete. As the side arm moieties can form excimer or exciplex, their triplet emissions should also appear in the broad peaks from 450 to 700 nm in addition to that from the main chains.…”

Section: Resultsmentioning

confidence: 99%

“… a The energy of the first peak of the phosphorescence spectrum is taken as the E T . b The phosphorescence data are taken from literatures182526. c sh means shoulder. d The quoted values are contributed from the isolated arm groups. e The triplet energy is determined by the first peak of silylene-diphenylene backbone. f The peaks are assigned by deconvolution of the total phosphorescence spectrum.…”

Section: Figurementioning

confidence: 99%

Bipolar and Unipolar Silylene-Diphenylene σ-π Conjugated Polymer Route for Highly Efficient Electrophosphorescence

Chang

Sharma

Hung

et al. 2016

Sci Rep

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σ-π conjugated polymer strategy is proposed for designing electroluminescent host polymers with silylene-diphenylene as the backbone repeat unit giving a high triplet energy (ET = 2.67 eV). By incorporation of high ET (3.0 eV) electron (oxadiazole, OXD) and hole (triphenyl amine, TPA) transport moieties, or TPA alone (in this case, the main chain acts as electron transport channel) as side arms on the silylene, the high ET bipolar and unipolar polymers are formed, allowing a use of iridium green phosphor (Ir(ppy)2(acac), Ir-G) (ET = 2.40 eV) as the dopant. The matching of energy levels of the dopant with the hosts, leading to charge trapping into it; and singlets and triplets of the exciplex and excimer can be harvested via energy transfer to the dopant. Using these host-guest systems as the emitting layer, chlorinated indium-tin-oxide (Cl-ITO) as the anode, and benzimidazole derivative (TPBI) as the electron transport layer, this two-layer device gives the high luminance efficiency 80.1 cd/A and external quantum efficiency 21.2%, which is the best among the report values for polymer light emitting diode (PLED) in the literatures. This example manifests that σ-π conjugated polymer strategy is a promising route for designing polymer host for efficient electrophosphorescence.

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Triplet excimer formation of triphenylamine and related chromophores in polystyrene films

Cited by 30 publications

References 1 publication

Photophysical Investigation of the Thermally Activated Delayed Emission from Films of m‐MTDATA:PBD Exciplex

Photophysical Investigation of the Thermally Activated Delayed Emission from Films of m‐MTDATA:PBD Exciplex

A Bipolar Host Material Containing Triphenylamine and Diphenylphosphoryl‐Substituted Fluorene Units for Highly Efficient Blue Electrophosphorescence

Bipolar and Unipolar Silylene-Diphenylene σ-π Conjugated Polymer Route for Highly Efficient Electrophosphorescence

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