Influence of the Anodic Work Function on the Performance of Organic Solar Cells

Frohne, Holger; Shaheen, Sean E.; Brabec, Christoph J.; Müller, David C.; Sariçiftçi, Niyazi Serdar; Meerholz, Klaus

doi:10.1002/1439-7641(20020916)3:9<795::aid-cphc795>3.0.co;2-a

Cited by 183 publications

(126 citation statements)

References 12 publications

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“…12 On the other hand, electrochemical modification of the PEDOT work function in PPV-based solar cells showed that the opencircuit voltage exactly followed the behavior as expected from the PEDOT work function. 13 This shows that the PE-DOT work function is not pinned in this system, which supports our estimate of the hole density at the interface. We use a recently developed drift-diffusion model to calculate the distribution of holes p͑x͒ as a function of distance x in the device.…”

Section: ͑1͒supporting

confidence: 83%

Diffusion-enhanced hole transport in thin polymer light-emitting diodes

2008

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Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. The transport of holes in polymer light-emitting diodes ͑PLEDs͒ based on poly͑2-methoxy, 5-͑2Ј ethylhexyloxy͒-p-phenylene vinylene͒ ͑MEH-PPV͒ is investigated as a function of layer thickness. For thicknesses smaller than 100 nm, the current in these thin PLEDs is strongly enhanced as compared to the expected space-charge limited ͑SCL͒ current. Applying the standard SCL model to measurements on a PLED with a thickness of only 40 nm results in an apparent increase of the hole mobility of a factor of 40. We show that this strong increase of the hole transport properties in these thin devices originates from the presence of an Ohmic hole contact. For Fermi-level alignment, holes diffuse from the contact into the MEH-PPV, forming an accumulation layer with a width of a few tens of nanometers. Due to the density dependence of the mobility, the hole transport in this accumulation region is strongly enhanced. For the analysis of thin PLEDs, it is therefore essential that both drift and diffusion of charge carriers are taken into account.

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Section: ͑1͒supporting

confidence: 83%

Diffusion-enhanced hole transport in thin polymer light-emitting diodes

2008

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“…In addition, the oxidation potential E ox of a PEDOT:PSS lm was measured using CV. 47 We assume that E ox of PEDOT:PSS measured using CV is equivalent to F measured using UPS and equate a linear scale between CV and UPS with PEDOT:PSS as the reference point. All other electrochemical states measured using CV from other polymers are referenced to this.…”

Section: Reaction Mechanismmentioning

confidence: 99%

Mixed interlayers at the interface between PEDOT:PSS and conjugated polymers provide charge transport control

et al. 2015

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Poly(3,4-ethylenedioxythiophene)-poly(styrenesulphonate) (PEDOT:PSS) is the most used organic hole injecting or hole transporting material. The hole carrying matrix PEDOT is highly doped by the acidic dopant PSS. When coated onto a substrate, PEDOT:PSS makes a highly uniform conductive layer and a thin (<5 nm) overlayer of PSS covers the air interface. Semiconducting polymer layers for organic photovoltaics or light emitting diodes are coated on top. In this article, we demonstrate that the PSS layer will mix with almost all conjugated polymers upon thermal annealing. Depending on the Fermi energy of the polymer an electrochemical reaction can take place, p-type doping the polymer at the interface between the PEDOT:PSS and the semiconducting polymer. We use chemical and spectroscopic analysis to characterize the polymer/PSS interlayer. We show that the stable and insoluble interlayer has a great effect on the charge injection and extraction from the interface. Finally we demonstrate and electronically model organic photovoltaic devices that are fabricated using these mixed interlayers.

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“…Frohne and coworkers systematically modified the work function of PEDOT:PSS films electrochemically [50,51]. The treatment of electrically polymerized PEDOT film in the presence of sodium-neutralized PSS resulted in PEDOT:PSS films with work function variations up to 1.3 eV, depending on the doping level.…”

Section: Figurementioning

confidence: 99%

“…The PEDOT:PSS film was then incorporated into poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV)/[6,6]-phenyl-fullerene-butyric acid methyl ester (PCBM) solar cells as the hole-transporting layer, and the compensation voltage, V0 (V0 is the potential at which the photocurrent equals the dark current, which is proportional to the Voc) tracks the work function of PEDOT:PSS. However, as the work function of PEDOT:PSS is beyond 0.3 V versus Ag/AgCl, the Vo plateaus [51]. Later, Li and coworkers found that the photovoltaic performance of poly(3-hexylthiophene) (P3HT):PCBM solar cells can be improved by incorporating a PEDOT:PSS IFL between the indium tin oxide (ITO) and the active layer [52].…”

Section: Figurementioning

confidence: 99%

Interfacial Layer Engineering for Performance Enhancement in Polymer Solar Cells

et al. 2015

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Improving power conversion efficiency and device performance stability is the most critical challenge in polymer solar cells for fulfilling their applications in industry at large scale. Various methodologies have been developed for realizing this goal, among them interfacial layer engineering has shown great success, which can optimize the electrical contacts between active layers and electrodes and lead to enhanced charge transport and collection. Interfacial layers also show profound impacts on light absorption and optical distribution of solar irradiation in the active layer and film morphology of the subsequently deposited active layer due to the accompanied surface energy change. Interfacial layer engineering enables the use of high work function metal electrodes without sacrificing device performance, which in combination with the favored kinetic barriers against water and oxygen penetration leads to polymer solar cells with enhanced performance stability. This review provides an overview of the recent progress of different types of interfacial layer materials, including polymers, small molecules, graphene oxides, fullerene derivatives, and metal oxides. Device performance enhancement of the resulting solar cells will be elucidated and the function and operation mechanism of the interfacial layers will be discussed. OPEN ACCESSPolymers 2015, 7 334

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Influence of the Anodic Work Function on the Performance of Organic Solar Cells

Cited by 183 publications

References 12 publications

Diffusion-enhanced hole transport in thin polymer light-emitting diodes

Diffusion-enhanced hole transport in thin polymer light-emitting diodes

Mixed interlayers at the interface between PEDOT:PSS and conjugated polymers provide charge transport control

Interfacial Layer Engineering for Performance Enhancement in Polymer Solar Cells

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