Enhanced Hole Injection in a Hybrid Organic–Inorganic Light-Emitting Diode

Morii, Katsuyuki; Omoto, Masayuki; Ishida, Masaya; Gräetzel, Michael

doi:10.1143/jjap.47.7366

Cited by 25 publications

(17 citation statements)

References 11 publications

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“…In the case where Q < 0.5 nm, the difference became greater, i.e., the Mo 3d states shifted to the low BE side relative to C 1s, with decreasing Q. While no clear feature assigned to reduced species (Mo 5þ or Mo 4þ ) was detected, in contrast to previous reports, [40,41] this shift tendency can be regarded as a sign of charge transfer (CT) from F8BT to MoO 3 , in other words MoO 3 was partially reduced by electron donation from F8BT. The present results suggest that the proportion of the reduced MoO 3 was more dominant, particularly when Q was small.…”

Section: Discussioncontrasting

confidence: 87%

“…[18,23] On the other hand, the occurrence of CT from F8BT to MoO 3 has been proposed based on XPS results, [41] and our present XPS results also support this proposition. Furthermore, the positive vacuum level shift, observed at Stage II, strongly suggests the generation of an interface dipole resulting in CT to the overlayer from the substrate.…”

Section: Discussionsupporting

confidence: 86%

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Origins of Improved Hole‐Injection Efficiency by the Deposition of MoO₃ on the Polymeric Semiconductor Poly(dioctylfluorene‐alt‐benzothiadiazole)

Nakayama

Morii

Suzuki

et al. 2009

Adv Funct Materials

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The electronic structure of the interfaces formed after deposition of MoO3 hole‐injection layers on top of a polymer light‐emitting material, poly(dioctylfluorene‐alt‐benzothiadiazole) (F8BT), is studied by ultraviolet photoelectron spectroscopy (UPS), X‐ray photoelectron spectroscopy and metastable atom electron spectroscopy. Significant band bending is induced in the F8BT film by MoO3 “acceptors” that spontaneously diffuse into the F8BT “host” probably driven by kinetic energy of the deposited hot MoO3. Further deposition leads to the saturation of the band bending accompanied by the formation of MoO3 overlayers. Simultaneously, a new electronic state in the vicinity of the Fermi level appears on the UPS spectra. Since this peak does not appear in the bulk MoO3 film, it can be assigned as an interface state between the MoO3 overlayer and underlying F8BT film. Both band bending and the interface state should result from charge transfer from F8BT to MoO3, and they appear to be the origin of the hole‐injection enhancement by the insertion of MoO3 layers between the F8BT light‐emitting diodes and top anodes.

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Section: Discussioncontrasting

confidence: 87%

Section: Discussionsupporting

confidence: 86%

Origins of Improved Hole‐Injection Efficiency by the Deposition of MoO₃ on the Polymeric Semiconductor Poly(dioctylfluorene‐alt‐benzothiadiazole)

Nakayama

Morii

Suzuki

et al. 2009

Adv Funct Materials

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“…These values correspond to samples prepared either through in situ metal oxidation or sublimation. However, MoO 3 layers have been reported to have work functions between 5.2 and 5.8 eV, for instance when exposed to air or deposited on gold . The discrepancy can arise from the thickness of the layer, reactions with the substrate, or environmental effects.…”

Section: Reducing Contact Resistance: Electrode Design and Beyondmentioning

confidence: 99%

Contact Resistance in Organic Field‐Effect Transistors: Conquering the Barrier

Waldrip

Jurchescu

Gundlach

et al. 2019

Adv Funct Materials

225

261

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Organic semiconductors have sparked interest as flexible, solution processable, and chemically tunable electronic materials. Improvements in charge carrier mobility put organic semiconductors in a competitive position for incorporation in a variety of (opto-)electronic applications. One example is the organic field-effect transistor (OFET), which is the fundamental building block of many applications based on organic semiconductors. While the semiconductor performance improvements opened up the possibilities for applying organic materials as active components in fast switching electrical devices, the ability to make good electrical contact hinders further development of deployable electronics. Additionally, inefficient contacts represent serious bottlenecks in identifying new electronic materials by inhibiting access to their intrinsic properties or providing misleading information. Recent work focused on the relationships of contact resistance with device architecture, applied voltage, metal and dielectric interfaces, has led to a steady reduction in contact resistance in OFETs. While impressive progress was made, contact resistance is still above the limits necessary to drive devices at the speed required for many active electronic components. Here, the origins of contact resistance and recent improvement in organic transistors are presented, with emphasis on the electric field and geometric considerations of charge injection in OFETs.semiconductors with superior intrinsic charge transport properties, there is a stringent need to improve the device properties in order to allow organic devices to fulfill their technological prospectives. In the organic semiconductor community, contact resistance (R C ) has come under increased scrutiny as it is apparent that the final device performance is often domi nated by carrier injection, rather than the transport through the semiconductor layer. Contact resistance can impact OFET development in multiple ways. First, if not accounted for, a high contact resistance may lead to inaccurate extraction of the device parameters. Second, any inaccuracies in parameter extraction can have significant consequences on material development, from generating incorrect structure-property relationships to discarding organic semiconductors whose efficient intrinsic electrical properties have been masked by inefficient contacts. Beyond OFET and semiconductor characterization, analog, low power, and high frequency applications require a greater level of device parameter control than has been obtained in typical DC, high-voltage OFETs. For analog applications, e.g., integration of conditioning circuits such as local sense amps for distributed flexible sensor arrays, nonlinearity of the transistor response inhibits proper functioning and limits applicability of common models used to design circuitry. Low power device development for novel materials are hindered by the high voltage turn-on and current suppression in devices with large R C . Considering high-frequency applications, Klauk suggest...

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“…To improve the injection efficiency of the hole carriers, the internal quantum efficiency (IQE) of the PLED should be enhanced until the anodes work function (WF) matches (as far as possible) that of the HTL. Many research groups [6][7][8][9] have deposited SiO 2 , MoO 3 , or TiO 2 thin film on the anode surface by sputter-coating or evaporation. Although these techniques improve and homogenize the WF of the anode surface, they insignificantly improve the IQE of the PLED.…”

mentioning

confidence: 99%

Enhanced Device Performances of Blue‐Emitting PLEDs Coupled with Silver‐Nanoicosahedrons

Chen

Huang

Cheng

et al. 2018

Part & Part Syst Charact

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Silver‐nanoicosahedron particles (AgNIPs) are produced by chemical reduction and photochemical methods and doped into the hole transport layer (HTL) or emissive layer (EML) of blue‐emitting polymer light‐emitting diodes (PLEDs) to improve their luminous efficiency. The optimal distributed‐densities of the AgNIPs are determined from current density–voltage–luminance measurements at different doping concentrations. The AgNIP dopant doses that maximize the average luminous efficiency of the proposed PLED are 6.71 µg cm−2 in EML (achieving 3.48 cd A−1) and 6.88 µg cm−2 in HTL (achieving 3.35 cd A−1). Although the luminous efficiencies of the blue‐emitting PLEDs fabricated by both doping methods are not significantly different, the maximum plasmonic enhancement (around 30‐fold) of the blue‐emitting PLED with AgNIPs in EML is red‐shifted to the green region (≈530 nm in the electroluminescence spectrum), seriously degrading the luminescent monochromaticity of the blue‐emitting PLED. The maximum plasmonic enhancement (around 33‐fold) of blue‐emitting PLED with AgNIPs in HTL occurred at 430 nm, overlapping the localized surface‐plasmon resonance extinctions of the AgNIPs in HTL (425 nm), thus favoring the enhancement of fluorescence emission. Therefore, to enhance the large‐area emission of blue‐emitting PLEDs, the AgNIPs should be doped in the HTL rather than the EML.

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Enhanced Hole Injection in a Hybrid Organic–Inorganic Light-Emitting Diode

Cited by 25 publications

References 11 publications

Origins of Improved Hole‐Injection Efficiency by the Deposition of MoO₃ on the Polymeric Semiconductor Poly(dioctylfluorene‐alt‐benzothiadiazole)

Origins of Improved Hole‐Injection Efficiency by the Deposition of MoO₃ on the Polymeric Semiconductor Poly(dioctylfluorene‐alt‐benzothiadiazole)

Contact Resistance in Organic Field‐Effect Transistors: Conquering the Barrier

Enhanced Device Performances of Blue‐Emitting PLEDs Coupled with Silver‐Nanoicosahedrons

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Enhanced Hole Injection in a Hybrid Organic–Inorganic Light-Emitting Diode

Cited by 25 publications

References 11 publications

Origins of Improved Hole‐Injection Efficiency by the Deposition of MoO3 on the Polymeric Semiconductor Poly(dioctylfluorene‐alt‐benzothiadiazole)

Origins of Improved Hole‐Injection Efficiency by the Deposition of MoO3 on the Polymeric Semiconductor Poly(dioctylfluorene‐alt‐benzothiadiazole)

Contact Resistance in Organic Field‐Effect Transistors: Conquering the Barrier

Enhanced Device Performances of Blue‐Emitting PLEDs Coupled with Silver‐Nanoicosahedrons

Contact Info

Product

Resources

About

Origins of Improved Hole‐Injection Efficiency by the Deposition of MoO₃ on the Polymeric Semiconductor Poly(dioctylfluorene‐alt‐benzothiadiazole)

Origins of Improved Hole‐Injection Efficiency by the Deposition of MoO₃ on the Polymeric Semiconductor Poly(dioctylfluorene‐alt‐benzothiadiazole)