Enhancing the contrast and power efficiency of organic light-emitting diodes using CuPc/TiOPc as an anti-reflection layer

Li, Jianfeng; Su, Shui‐Hsiang; Hwang, Kao-Shing; Yokoyama, M.

doi:10.1088/0022-3727/40/8/004

Cited by 18 publications

(15 citation statements)

References 22 publications

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“…Titanyl phthalocyanine (TiOPc) is an excellent optoelectronic molecule that exhibits exceptional absorption peaks in the visible and near-infrared regions. , TiOPc crystals and films are some of the most important molecular materials due to their practical and potential applications in photovoltaic cells, , organic light emitting diodes, , field effect transistors, and xerographic photoconductors . However, realization of highly efficient devices heavily relies on precise control of their structures due to the presence of abundant polymorphism. − Four polymorphs of the TiOPc crystals achieved by different preparation methodologies and post-treatment procedures have been reported, including monoclinic phases I and C, triclinic phase II, and a third monoclinic phase Y .…”

Section: Introductionmentioning

confidence: 99%

Precursor Structures for Polymorphic Titanyl Phthalocyanine Crystal Phases on Au(111): A High-Resolution STM Study

et al. 2019

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The adsorption, assembly, and growth mechanism of the optoelectronic titanyl phthalocyanine (TiOPc) molecules on Au(111) were carefully investigated by low-temperature and highresolution scanning tunneling microscopy (STM). Three domains, i.e., Y, I, and II, were formed on Au(111) with its coverage increased up to six monolayers (MLs), as structurally scrutinized at the submolecular level. The TiOPc molecules were adsorbed with their Pc planes parallel to the substrate surface in domains Y and I, while the Pc planes tilted against the surface with two lobes pointed toward the vacuum in domain II. A growth mode transition from layer-by-layer to bilayer-by-bilayer was experimentally observed in domains Y and I when the TiOPc coverage exceeded 2 ML, while domain II remained unchanged. The stable double-layer island growth, i.e., O-up and O-down in odd-and even-numbered layers, respectively, was maintained as the coverage increased in domains Y and I. Detailed structural analyses based on the submolecular resolution STM imaging indicated that domains Y, I, and II corresponded to polymorphic crystal phases Y-TiOPc, I-TiOPc, and deformed II-TiOPc grown on Au(111), which were frequently missed in previous studies due to the lack of subtle structural details by high-resolution images. Such a structural clarification of the grown TiOPc films should help in the understanding of the relationship between their optoelectronic device performance and polymorphism of the polycrystalline TiOPc thin films.

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Section: Introductionmentioning

confidence: 99%

Precursor Structures for Polymorphic Titanyl Phthalocyanine Crystal Phases on Au(111): A High-Resolution STM Study

et al. 2019

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“…Due to its high photoelectronic activity in the IR region, titanyl phthalocyanine (TiOPc) is an excellent photocarrier generation material . It is been widely explored because of its potential applications in organic photovoltaic solar cells, − organic light emitting diodes, , and field effect transistors . Bulk or thin film TiOPc materials exhibit four polymorphs: monoclinic phases I, C, and Y as well as triclinic phase II. − The carrier generation efficiency in different TiOPc crystal form is remarkably different because the intermolecular interaction between the TiOPc molecules has a profound impact on its photoresponse. , In order to obtain a uniform crystal with a high efficiency, it is vital to understand the growth mechanism and structure of the TiOPc molecular films.…”

Section: Introductionmentioning

confidence: 99%

“…Due to its high photoelectronic activity in the IR region, 1 titanyl phthalocyanine (TiOPc) is an excellent photocarrier generation material. 2 It is been widely explored because of its potential applications in organic photovoltaic solar cells, 3−5 organic light emitting diodes, 6,7 and field effect transistors. 8 Bulk or thin film TiOPc materials exhibit four polymorphs: monoclinic phases I, C, and Y as well as triclinic phase II.…”

Section: Introductionmentioning

confidence: 99%

Adsorption and Assembly of Photoelectronic TiOPc Molecules on Coinage Metal Surfaces

et al. 2018

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The adsorption and assembly of individual and submonolayered TiOPc on Ag(111), Cu(111), and Au(111) have been investigated by scanning tunneling microscopy (STM) and spectroscopy. High resolution STM imaging as well as dI/dV and I−z measurements reveal that TiOPc adsorbed on Ag(111) adopts either O-up or O-down configuration. An intermolecular dipole−dipole interaction leads to the fact that neighboring TiOPc molecules in alternating O-up and O-down configurations form a highly ordered checkerboard assembly structure on Ag(111). However, no large size TiOPc assemblies are observed on Cu(111) and Au(111) due to low surface mobility and diffusivity caused by strong TiOPc−Cu(111) interaction and the templating effect by the reconstructed herringbone structure of Au(111), respectively. Instead, molecular dimers on both Au(111) and Cu(111) as well as molecular aggregates on Au(111) are routinely observed in experiments, indicating that the intermolecular dipole−dipole attraction and weak hydrogen bonding coplay an important role in steering the adsorption and assembly of the TiOPc molecules on the coinage metal surfaces.

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“…Besides that, it is important to stress that the devices using IZO anodes present the highest power efficiency for the three EMLs. Moreover, the superior power efficiency of IZO based devices compared with ITO is attributed to a better charge balance, which in principle should lead to a change in the position of the recombination zone 13, 40…”

Section: Resultsmentioning

confidence: 99%

Role of Room Temperature Sputtered High Conductive and High Transparent Indium Zinc Oxide Film Contacts on the Performance of Orange, Green, and Blue Organic Light Emitting Diodes

Gonçalves

Barquinha

Pereira

et al. 2011

Plasma Processes & Polymers

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The core of this paper concerns the use of an amorphous transparent conductive oxide (a‐TCO), whose performance is on par with the classical indium tin oxide (ITO) films as a transparent contact in organic light emitting diodes (OLEDs). The main advantage of indium zinc oxide (IZO) films relies on their amorphous structure and high mobility that turns them likely to be used with high conductivity and high transmittance even at the infrared region. The mobility of IZO films (47.8 cm2 · V−1 · s−1) surpasses the one exhibited by ITO films (26.4 cm2 · V−1 · s−1), which along with its smoother surface and better current distribution plays an important role on OLEDs performance. Besides their similar turn‐on voltage, the devices using IZO anodes exhibit higher power efficiency than the ITO ones, which is 66, 18, and 62% for orange, green, and blue OLEDs, respectively. These results suggest that IZO can potentially be applied as an anode in full color displays based on OLEDs.

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Enhancing the contrast and power efficiency of organic light-emitting diodes using CuPc/TiOPc as an anti-reflection layer

Cited by 18 publications

References 22 publications

Precursor Structures for Polymorphic Titanyl Phthalocyanine Crystal Phases on Au(111): A High-Resolution STM Study

Precursor Structures for Polymorphic Titanyl Phthalocyanine Crystal Phases on Au(111): A High-Resolution STM Study

Adsorption and Assembly of Photoelectronic TiOPc Molecules on Coinage Metal Surfaces

Role of Room Temperature Sputtered High Conductive and High Transparent Indium Zinc Oxide Film Contacts on the Performance of Orange, Green, and Blue Organic Light Emitting Diodes

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