Nanoscale Surface Morphology and Rectifying Behavior of a Bulk Single‐Crystal Organic Semiconductor

Menard, Etienne; Marchenko, Alexandr; Podzorov, Vitaly; Gershenson, M. E.; Fichou, Denis; Rogers, John A.

doi:10.1002/adma.200502569

Cited by 95 publications

(78 citation statements)

References 24 publications

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“…Of particular interest in that context is the recent discovery of the exceptionally low-threshold injection characteristics of rubrene crystals 2 . We implement here a resonant scheme that permits to drive electroluminescence (EL) with an extremely low turn-on voltage.…”

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confidence: 99%

Upconversion injection in rubrene/perylene-diimide-heterostructure electroluminescent diodes

Pandey

Nunzi

2007

Applied Physics Letters

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We implement and demonstrate in this paper a scheme that permits to drive electroluminescence with an extremely low turn-on voltage. The device behaves like compound semiconductors, in which the electroluminescence turn-on voltage is about the same as the open circuit voltage for the photovoltaic effect. However, the electroluminescence turn-on voltage is about half of the band gap of the emitting material, that cannot be explained using current models of charge injection in organic semiconductors. We hereby propose explanation through an Auger-type two-step injection mechanism.2 Apart from their ease of fabrication and suitability to large area applications, there are many unexplored fields related to the peculiar physics of conjugated materials 1 . Of particular interest in that context is the recent discovery of the exceptionally low-threshold injection characteristics of rubrene crystals 2 . We implement here a resonant scheme that permits to drive electroluminescence (EL) with an extremely low turn-on voltage. The heterostructure device behaves like compound semiconductors, in which the EL turn-on voltage is about the same as the open circuit voltage for the photovoltaic effect. Surprisingly however, this places the EL turn-on voltage at about half of the rubrene band gap (2.2 eV). The physical interpretation can be found into the so-called Auger mechanism 3 that we could implement in our molecular heterojunction diode. 5,6,11,12-tetraphenylnaphthacene, commonly known as rubrene (Aldrich, sublimed grade, see insert in Fig. 1a), was used as a hole-transporting material, while N,N'-ditridecylperylene-3, 4, 9, 10-tetracarboxylic diimide (PTCDI, Aldrich, purum grade) was used as an electron transporting material. Both rubrene and PTCDI are widely studied semiconductors with among the highest fieldeffect mobility for holes 4 and electrons 5 , respectively. Moreover, rubrene is also currently used as a yellow dopant for achieving efficient light emitting diodes (LED) 6 and efficient photovoltaic (PV) not find explanation using current models of charge injection in organic semiconductors 8 , as we discuss in the following. Under 1V bias, electron-hole pairs with ~1eV electrochemical potential recombining at the rubrene/C 60 interface must create ~2eV excitons in rubrene to yield effective electroluminescence with the characteristic color of rubrene (Fig.2a). To understand better that halfgap EL phenomenon, it is necessary to figure the energetic steps involved, starting from charge injection at the organic-metal interface. Figure 3a figure 3a, that is not the case as figure 1 shows; Second, the energy barrier for thermal emission from PTCDI-LUMO to rubrene-LUMO is F i ≈ 1eV and the thermal emission current density can be estimated from the Richardson-Dushman equation:J th = AT 2 .exp(-F i /kT), where the theoretical value of A is 123 A.cm -2 K -2 . One obtains J th ≈ 50 pA/cm 2 , very far from the J ≈ 1 mA/cm 2 measured at V = 1V (Figure 1b). EL at a relatively lower 5 voltage than the semiconductor band-gap has b...

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confidence: 99%

Upconversion injection in rubrene/perylene-diimide-heterostructure electroluminescent diodes

Pandey

Nunzi

2007

Applied Physics Letters

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“…The FWHM of the PL spectra of the amorphous DA NPs was estimated to be about 157 nm while that of the crystalline DA NPs was about 51 nm. The blue-shifted for the crystalline DA NPs is due to the nano-size crystalline structure effect, and the narrowed LCM PL spectra of the crystalline DA NPs is originated from the light emission of the structural confinement bands due to the single crystal structure [27][28][29]. Fig.…”

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confidence: 99%

Sharp and bright photoluminescence emission of single-crystalline diacetylene nanoparticles

Kim

Park

et al. 2016

Journal of the Korean Physical Society

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Amorphous nanoparticles (NPs) of diacetylene (DA) molecules were prepared by using a reprecipitation method. After crystallization through solvent-vapor annealing process, the highly crystalline DA NPs show different structural and optical characteristics compared with the amorphous DA NPs. The single crystal structure of DA NPs was confirmed by high-resolution transmission electron microscopy (HR-TEM) and wide angle X-ray scattering (WAXS). The luminescence color and photoluminescence (PL) characteristics of the DA NPs were measured using color charge-coupled device (CCD) images and high-resolution laser confocal microscope (LCM). The crystalline DA NPs emit bright green light emission compared with amorphous DA NPs and the main PL peak of the crystalline DA NPs exhibits relative narrow and blue shift phenomena due to enhanced interaction between DA molecular in the nano-size crystal structure.

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“…47 STM investigations were carried out also on single-crystal surfaces in ambient air and revealed a herringbone-like motif similar to that found in the bulk. 48 In this paper, we investigate the adsorption and self-assembly properties of rubrene molecules on the O-Cu nanotemplate by in situ high-resolution STM in UHV. We show that rubrene adsorbs preferentially on the clean Cu(110) stripes.…”

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confidence: 99%

Molecular Assembly of Rubrene on a Metal/Metal Oxide Nanotemplate

et al. 2007

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We investigated the adsorption properties and self-assembly of rubrene molecules on the copper oxide nanotemplate formed by high-temperature exposure of Cu (110) to molecular oxygen. Using high-resolution scanning tunneling microscopy under ultrahigh-vacuum conditions, we observed a complex variety of selfassembled motifs, driven by competing effects such as the chemical affinity between the organic molecule and the surface, surface coverage, and spatial confinement of the rubrene molecules within the rows of the template.

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Nanoscale Surface Morphology and Rectifying Behavior of a Bulk Single‐Crystal Organic Semiconductor

Cited by 95 publications

References 24 publications

Upconversion injection in rubrene/perylene-diimide-heterostructure electroluminescent diodes

Upconversion injection in rubrene/perylene-diimide-heterostructure electroluminescent diodes

Sharp and bright photoluminescence emission of single-crystalline diacetylene nanoparticles

Molecular Assembly of Rubrene on a Metal/Metal Oxide Nanotemplate

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