Alternative model for injection-limited current into organic solids

Fathollahi, Mohammad-Reza; Sharifi, Mohammad-Javad; Boroumand, Farhad Akbari; Raissi, Farshid; Mohajerani, Ezeddin

doi:10.1117/1.jpe.5.057610

Cited by 6 publications

(7 citation statements)

References 30 publications

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“…The current density–voltage ( J–V ) characteristics of the fabricated UV detectors were measured under dark and UV light and are shown in Figure (a). It can be clearly observed that the devices exhibit typical rectifying behavior in dark, indicating the formation of a simple p‐n junction at the interface of ZnO NPs and BFE polymer . While the device exhibits rectification ratio of 64 at ±1.5 V, its dark current density is 1.3 × 10 −7 A/cm 2 at −1.5 V. This value is the range of the lowest reported values for UV photodetectors with TiO 2 /PVK and ZnO/PFH structures.…”

Section: Resultsmentioning

confidence: 77%

Low noise ultraviolet photodetector with over 100% enhanced lifetime based on polyfluorene copolymer and ZnO nanoparticles

Azadinia

Fathollahi

Ameri

et al. 2018

J of Applied Polymer Sci

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Stability and noise current of a hybrid UV photodetector with inverted planar heterojunction (PHJ) structure indium‐tin‐oxide/ZnO nanoparticles (NPs)/poly[9,9′‐dioctyl‐fluorene‐2,7‐diyl]‐copoly[diphenyl‐p‐tolyl‐amine‐4,4′‐diyl] (BFE)/Ag are investigated. ZnO NPs as the acceptor and BFE as the donor were deposited as the active layer. Under UV light illumination, light to dark current ratio of about 102 is observed at a very low bias voltage of −1.5 V. The spectral response of the device is located near UV region with a maximum responsivity of ∼57 mA/W at wavelength of 350 nm. In particular, the prepared device exhibits remarkably higher photoresponse (∼350%) and stability (∼115%) enhancement under ambient condition compared to the reference device. In addition, the presented results show that the noise current of our device with PHJ structure is about an order of magnitude lower than that of commonly used bulk heterojunction system. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46533.

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Section: Resultsmentioning

confidence: 77%

Low noise ultraviolet photodetector with over 100% enhanced lifetime based on polyfluorene copolymer and ZnO nanoparticles

Azadinia

Fathollahi

Ameri

et al. 2018

J of Applied Polymer Sci

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“…The numerical model solves four equations self-consistently to obtain the dynamic of the carriers 47 61 62 . The carrier transition between the electrode and the organic molecules was formulated by Bardeen tunneling theory and basically accounts for the localized nature of the electronics states in the organic solids 61 63 64 :…”

Section: Methodsmentioning

confidence: 99%

“…The carrier transition among the organic molecules with localized states was modeled by the master equation as follows 47 61 62 64 :…”

Section: Methodsmentioning

confidence: 99%

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Organic/Organic Heterointerface Engineering to Boost Carrier Injection in OLEDs

Fathollahi

Ameri

Mohajerani

et al. 2017

Sci Rep

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We investigate dynamic formation of nanosheet charge accumulations by heterointerface engineering in double injection layer (DIL) based organic light emitting diodes (OLEDs). Our experimental results show that the device performance is considerably improved for the DIL device as the result of heterointerface injection layer (HIIL) formation, in comparison to reference devices, namely, the current density is doubled and even quadrupled and the turn-on voltage is favorably halved, to 3.7 V, which is promising for simple small-molecule OLEDs. The simulation reveals the (i) formation of dynamic p-type doping (DPD) region which treats the quasi Fermi level at the organic/electrode interface, and (ii) formation of dynamic dipole layer (DDL) and the associated electric field at the organic/organic interface which accelerates the ejection of the carriers and their transference to the successive layer. HIIL formation proposes alternate scenarios for device design. For instance, no prerequisite for plasma treatment of transparent anode electrode, our freedom in varying the thicknesses of the organic layers between 10 nm and 60 nm for the first layer and between 6 nm and 24 nm for the second layer. The implications of the present work give insight into the dynamic phenomena in OLEDs and facilitates the development of their inexpensive fabrication for lighting applications.

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“…Recently, the application of metal buffers such as indium has been presented to enhance device properties . Also, many studies have been conducted in order to understand the physics of carrier transfer at the metal/organic interface in an OLED structure.…”

Section: Introductionmentioning

confidence: 99%

Ultrathin buffer layer at organic/organic interface for managing the recombination profile in organic light‐emitting diodes: Metal versus dielectric buffer

Kalhor

Mohajerani

Hashemipour

et al. 2016

J of Applied Polymer Sci

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We report on the utilization of an ultrathin buffer layer at the organic/organic (O/O) interface to enhance device efficiency in organic light‐emitting diodes. Two different kinds of buffer layers are examined: metal and dielectric. It is shown that employment of an ultrathin Ag layer with a thickness of 1–2 nm enhances the device performance, while a MgF2 dielectric buffer cannot affect the device properties considerably. In particular, the turn‐on voltage of the device with an appropriate buffer layer is reduced about 3 V, its current efficiency increases by a factor of more than three, and the power efficiency increases by a factor of more than five in comparison to the control device when a Ag buffer layer is introduced at the O/O interface. By employment of the buffer layer at the interface, an accumulation of current carriers appears within the device that redistribute the recombination profile toward the interior part of the emissive layer. Also, morphological examinations reveal that distinguishable phase segregation occurs in the blend of the hole‐transport layer. In particular, the polymer component remains at the surface and facilitates the hole transport into the successive layers. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43894.

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Alternative model for injection-limited current into organic solids

Cited by 6 publications

References 30 publications

Low noise ultraviolet photodetector with over 100% enhanced lifetime based on polyfluorene copolymer and ZnO nanoparticles

Low noise ultraviolet photodetector with over 100% enhanced lifetime based on polyfluorene copolymer and ZnO nanoparticles

Organic/Organic Heterointerface Engineering to Boost Carrier Injection in OLEDs

Ultrathin buffer layer at organic/organic interface for managing the recombination profile in organic light‐emitting diodes: Metal versus dielectric buffer

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