Interface Modification to Improve Hole‐Injection Properties in Organic Electronic Devices

Choulis, Stelios A.; Choong, Vi-En; Patwardhan, Aditee; Mathai, Mathew; So, Franky

doi:10.1002/adfm.200500443

Cited by 120 publications

(69 citation statements)

References 39 publications

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“…After the annealing of PEDOT:PSS, all processes were performed under inert conditions. A solution of TFB in p-xylene at a concentration of 7.0 mg ml À 1 was spin-cast onto PEDOT:PSS and then annealed at 200°C for 60 min to yield a 20-nm-thick film insoluble in common organic solvents 39,40 . For the fabrication of the green OLEDs, a blend of TCzBP, TPCz and Ir(ppy) 3 in a tetrahydrofuran solution at a concentration of 5.5 mg ml À 1 was spin-cast onto the TFB layer and then annealed at 150°C for 30 min to yield the green EML, with a thickness of 30 nm.…”

Section: Methodsmentioning

confidence: 99%

Solution-processed multilayer small-molecule light-emitting devices with high-efficiency white-light emission

et al. 2014

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Recent developments in the field of p-conjugated polymers have led to considerable improvements in the performance of solution-processed organic light-emitting devices (OLEDs). However, further improving efficiency is still required to compete with other traditional light sources. Here we demonstrate efficient solution-processed multilayer OLEDs using small molecules. On the basis of estimates from a solvent resistance test of small host molecules, we demonstrate that covalent dimerization or trimerization instead of polymerization can afford conventional small host molecules sufficient resistance to alcohols used for processing upper layers. This allows us to construct multilayer OLEDs through subsequent solution-processing steps, achieving record-high power efficiencies of 36, 52 and 34 lm W À 1 at 100 cd m À 2 for solution-processed blue, green and white OLEDs, respectively, with stable electroluminescence spectra under varying current density. We also show that the composition at the resulting interface of solution-processed layers is a critical factor in determining device performance.

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Section: Methodsmentioning

confidence: 99%

Solution-processed multilayer small-molecule light-emitting devices with high-efficiency white-light emission

et al. 2014

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“…The homogeneous polymer complex of poly-ethylenedioxythiophene (PEDOT), oxidized with polystyrene sulphonate (PSS), has extensively been used as buffer layer in organic optoelectronic applications due to its high electrical conductivity and transparency in the visible region [1][2][3][4][5]. However, degradation related issues of PEDOT: PSS can be a parameter that might influence the lifetime performance of organic optoelectronic devices and other applications in which it participates [6][7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Conductivity Degradation Study of PEDOT: PSS Films under Heat Treatment in Helium and Atmospheric Air

Vitoratos¹,

Sakkopoulos²,

Paliatsas³

et al. 2012

OJOPM

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PEDOT:PSS buffer layers have been processed with the standard annealing step used for organic solar cells device applications. The d.c. conductivity σ as a function of temperature for two heating rates under He and atmospheric air was studied. Moreover, the stability of the conductivity was investigated at different temperatures and environments vs time.The main results can be summarized in the following: the increase of σ due to the thermal activation of the carriers and the improvement of the crystallinity compete with the decrease of σ resulting from the irreversible structural degradation of the polymer chains promoted by the oxygen and moisture of the atmospheric air. The heat treatment time and the temperature at which the two competing mechanisms result in a maximum of the electrical conductivity have been determined and results are discussed relevant to organic optoelectronic devices containing PEDOT: PSS buffer layers.

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“…However, this device in comparison with the single-layer device of PYPBD has a remarkably reduced onset voltage due to the donor-acceptor surface of D1. This dendrimer was optimized in a two-layer device of ITO/PEDOT:PSS/TFB/dendrimer/Ca/Al, where poly(9,9-dioctylfluorene-co-N-(4-butylphenyl)-diphenylamine) (TFB) worked as hole-transporting material (HOMO: −5.30 eV, LUMO: −2.10 eV) [63]. The dendrimer layer was spin-coated on a TFB surface (Supplementary Materials).…”

Section: Oled Device Performancesmentioning

confidence: 99%

Blue Light Emitting Polyphenylene Dendrimers with Bipolar Charge Transport Moieties

et al. 2016

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Two light-emitting polyphenylene dendrimers with both hole and electron transporting moieties were synthesized and characterized. Both molecules exhibited pure blue emission solely from the pyrene core and efficient surface-to-core energy transfers when characterized in a nonpolar environment. In particular, the carbazole-and oxadiazole-functionalized dendrimer (D1) manifested a pure blue emission from the pyrene core without showing intramolecular charge transfer (ICT) in environments with increasing polarity. On the other hand, the triphenylamine-and oxadiazole-functionalized one (D2) displayed notable ICT with dual emission from both the core and an ICT state in highly polar solvents. D1, in a three-layer organic light emitting diode (OLED) by solution processing gave a pure blue emission with Commission Internationale de l'Éclairage 1931 CIE xy = (0.16, 0.12), a peak current efficiency of 0.21 cd/A and a peak luminance of 2700 cd/m 2 . This represents the first reported pure blue dendrimer emitter with bipolar charge transport and surface-to-core energy transfer in OLEDs.

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Interface Modification to Improve Hole‐Injection Properties in Organic Electronic Devices

Cited by 120 publications

References 39 publications

Solution-processed multilayer small-molecule light-emitting devices with high-efficiency white-light emission

Solution-processed multilayer small-molecule light-emitting devices with high-efficiency white-light emission

Conductivity Degradation Study of PEDOT: PSS Films under Heat Treatment in Helium and Atmospheric Air

Blue Light Emitting Polyphenylene Dendrimers with Bipolar Charge Transport Moieties

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