Charge injection and accumulation in organic light-emitting diode with PEDOT:PSS anode

Weis, Martin; Otsuka, Takako; Taguchi, Dai; Manaka, Takaaki; Iwamoto, Mitsumasa

doi:10.1063/1.4918556

Cited by 24 publications

(13 citation statements)

References 35 publications

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“…On the other hand, although the secondary doping effect is usually assumed, it is still not reliably confirmed and discussion on the origin of the conductivity improvement is often carried out. [11][12][13] It should be mentioned here that conductive PEDOT:PSS layers have been envisioned as electrode layers for OLEDs [14][15][16][17] and organic solar cells 18,19 as well as organic transistors. 20,21 Hence, the deep understanding of PEDOT:PSS conductivity enhancement by the secondary doping effect has high potential for application.…”

Section: Introductionmentioning

confidence: 99%

Secondary doping in poly(3,4‐ethylenedioxythiophene):Poly(4‐styrenesulfonate) thin films

Nevrela

Micjan

Novota

et al. 2015

J Polym Sci B Polym Phys

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The electrical and structural properties of poly (3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) thin films deposited from aqueous dispersion using different concentrations of selected secondary dopants are studied in detail. An improvement of the electrical conductivity by three orders of magnitude is achieved for dimethyl sulfoxide, sorbitol, ethylene glycol, and N,N-dimethylformamide, and the secondary dopant concentration dependence of the conductivity exhibits almost identical behavior for all investigated secondary dopants. Detailed analysis of the surface morphology and Raman spectra reveals no presence of the secondary dopant in fabricated films, and thus the dopants are truly causing the secondary doping effect. Although the ratio of benzenoid and quinoid vibrations in Raman spectra is unaffected by doping, the phase transition in PEDOT:PSS films owing to doping is confirmed. Further analysis of temperature-dependent conductivity reveals 1D variable range hopping (VRH) charge transport for undoped PEDOT:PSS, whereas highly conductive doped PEDOT:PSS films exhibit 3D VRH charge transport. We demonstrate that the charge-hopping dimensionality change should be a fundamental reason for the conductivity enhancement.

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Section: Introductionmentioning

confidence: 99%

Secondary doping in poly(3,4‐ethylenedioxythiophene):Poly(4‐styrenesulfonate) thin films

Nevrela

Micjan

Novota

et al. 2015

J Polym Sci B Polym Phys

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“…Probing carrier behaviors in combination with charge accumulation at the interface is particularly important, because the Maxwell-Wagner effect suggests carrier accumulation at the interface of layers, and this accumulation contributes to form space charge field. Consequently, EFISHG measurement coupled with the Maxwell-Wagner model analysis is very helpful for this purpose [28,29,89,134,135]. layers, and non-reversal charging and discharging processes resulted from the different carrier behaviors accompanied by ordinary green EL [29,89].…”

Section: A Double Layer El Diodesmentioning

confidence: 99%

Modeling and visualization of carrier motion in organic films by optical second harmonic generation and Maxwell-displacement current

Iwamoto¹,

Manaka²,

Taguchi³

2015

J. Phys. D: Appl. Phys.

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Probing and modeling of carrier motions in materials as well as in electronic devices is a fundamental research subject in science and electronics. According to the Maxwell electromagnetic field theory, carriers are a source of electric field. Therefore, by probing dielectric polarization caused by the electric field arising from moving carriers and dipoles, we can find a way to visualize the carrier motions in materials and in devices. The techniques used here are an electrical Maxwell-displacement current (MDC) measurement and a novel optical method based on electric field induced optical second harmonic generation (EFISHG) measurement. The MDC measurement probes changes of induced charge on electrodes, while the EFISHG probes nonlinear polarization induced in organic active layers due to coupling of electron clouds of molecules and electromagnetic waves of incident laser beam in the presence of dc field caused from electrons and holes. Both measurements allow us to probe dynamical carrier motions in solids through detection of dielectric polarization phenomena originated from dipolar motions and electron transport. In this Topical review, on the basis of the Maxwell's electro-magnetism theory in 1873, which stems from the Faraday's idea, the concept for probing electron and hole transport in solids by using the EFISHG is discussed in comparison with the conventional time of flight (TOF) measurement. We then visualize carrier transit in organic devices, i.e., organic field effect transistors, organic light emitting diodes, organic solar cells, and others. We also show that visualizing EFISHG microscopic image is a novel way for characterizing the anisotropic carrier transport in organic thin films. We also discuss the concept of the detection of rotational dipolar motions in monolayers by means of the MDC measurement, which is capable of probing the change of dielectric spontaneous polarization formed by dipoles in organic monolayers. Finally we conclude that ideas and experiments on EFISHG and MDC lead to a novel way for analyzing dynamical motions of electrons, holes, and dipoles in solids, thus these are available in organic electronic device application. to Eq. (1), we obtain the following equation:

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“…The stored charges in OLEDs behave noticeably under transient condition since they are sensitive to the change of electric field. Thus, some transient approaches were used to investigate these excess space charges, e.g., transient electroluminescence( EL ) measurement [ 12 , 27 , 28 , 29 , 30 ], impedance spectroscopy (IS) [ 31 , 32 , 33 , 34 , 35 , 36 ], and photo charge extraction by linearly increasing voltage (photo-CELIV) [ 37 , 38 , 39 , 40 ], etc. Transient electroluminescence measurement is often used to study the mechanism involved are carrier capture, exciton quenching and emission by driving the device through pulses.…”

Section: Introductionmentioning

confidence: 99%

“…The defect density can also be determined by capacitance under illumination [ 47 ]. Among these works, some C-V characteristics just present one peak [ 43 , 44 , 45 ], but it is also intriguing to find two peaks in some experiments [ 34 , 44 , 47 , 48 , 49 ].…”

Section: Introductionmentioning

confidence: 99%

Optical Capacitance/Conductance-Voltage Characteristics of Stored Charges in Organic Light-Emitting Diodes

Zhang

Wang

et al. 2020

Molecules

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In this paper, capacitance/conductance-voltage characteristics (C/G-V) under illumination was achieved to investigate the dynamic mechanism of stored charges in OLEDs with a structure of ITO/ PEDOT:PSS/PMMA/Alq3/Al. For all devices, at least two peaks presented in the optical capacitance-voltage curve. Compared to curves of devices under dark, the first peak increased remarkably with a deviation to Vbi, which can be explained in the form of stored charges combined with the optical conductance characteristics. It was also found that a great decrease in capacitance is followed by the collapse of the first peak with PMMA thickness increased. It can account for the presence of interfacial charges, which is proved further by the conductance curves. To the device with 10 nm PMMA, a third peak took place in optical capacitance and it was due to the storage of electrons by PMMA. Also, the first capacitance peak enhanced approximate linearly as the illumination power increased, which can verify the contribution of the stored charges. Additionally, it shows the potential for the stored charges in optical detections.

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Charge injection and accumulation in organic light-emitting diode with PEDOT:PSS anode

Cited by 24 publications

References 35 publications

Secondary doping in poly(3,4‐ethylenedioxythiophene):Poly(4‐styrenesulfonate) thin films

Secondary doping in poly(3,4‐ethylenedioxythiophene):Poly(4‐styrenesulfonate) thin films

Modeling and visualization of carrier motion in organic films by optical second harmonic generation and Maxwell-displacement current

Optical Capacitance/Conductance-Voltage Characteristics of Stored Charges in Organic Light-Emitting Diodes

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