Influence of Electron Extracting Interface Layers in Organic Bulk‐Heterojunction Solar Cells

Singh, Charanjit; Li, Cheng; Mueller, Christian; Hüttner, Sven; Thelakkat, Mukundan

doi:10.1002/admi.201500422

Cited by 8 publications

(9 citation statements)

References 50 publications

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“…To gain further insight into the character of the CT states present in the different systems, we additionally performed electroabsorption spectroscopy on bilayer devices. In this technique, one applies a varying electric field F = F DC + F AC cos(ω t ) to the sample and measures the change in absorption Δα due to the quadratic Stark effect and the nonzero second-order term of the linear Stark effect. − We measured electroabsorption from about 3.2 eV down to 1.2 eV to cover the full range of excitation, from bulk CT states in the fullerenes above 2.0 eV to the interfacial CT states in the sub-band-gap region Figure shows the spectra for all three acceptors in a bilayer device with PCDTBTOx measured at the same internal field.…”

Section: Resultsmentioning

confidence: 99%

Does Electron Delocalization Influence Charge Separation at Donor–Acceptor Interfaces in Organic Photovoltaic Cells?

et al. 2018

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We use bilayer devices with a series of three fullerene acceptors differing in order and intermolecular coupling to systematically explore the influence of electron delocalization in the acceptor phase on the dissociation efficiency of charge transfer states. Structural information from GIWAXS measurements is combined with the results of optical and electrical characterization as well as theoretical modeling.Our results indicate that an increase in CT-dissociation efficiency is directly coupled to an enhancement in electron delocalization that is particularly prominent for C 60 which forms crystalline domains. Therefore, our results substantiate the concept of delocalization of electrons taking a positive role in the charge separation process, and of acceptor crystallinity being crucial in this respect.

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Section: Resultsmentioning

confidence: 99%

Does Electron Delocalization Influence Charge Separation at Donor–Acceptor Interfaces in Organic Photovoltaic Cells?

et al. 2018

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“…External quantum efficiency (EQE) measurements were performed under both dark and white light bias conditions at short circuit conditions via a Bentham PVE 300 assembly unit. More details have been published elsewhere 57 .…”

Section: Methodsmentioning

confidence: 99%

Plasmonic nanomeshes: their ambivalent role as transparent electrodes in organic solar cells

Stelling

Singh

Karg

et al. 2017

Sci Rep

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231

120

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In this contribution, the optical losses and gains attributed to periodic nanohole array electrodes in polymer solar cells are systematically studied. For this, thin gold nanomeshes with hexagonally ordered holes and periodicities (P) ranging from 202 nm to 2560 nm are prepared by colloidal lithography. In combination with two different active layer materials (P3HT:PC61BM and PTB7:PC71BM), the optical properties are correlated with the power conversion efficiency (PCE) of the solar cells. A cavity mode is identified at the absorption edge of the active layer material. The resonance wavelength of this cavity mode is hardly defined by the nanomesh periodicity but rather by the absorption of the photoactive layer. This constitutes a fundamental dilemma when using nanomeshes as ITO replacement. The highest plasmonic enhancement requires small periodicities. This is accompanied by an overall low transmittance and high parasitic absorption losses. Consequently, larger periodicities with a less efficient cavity mode, yet lower absorptive losses were found to yield the highest PCE. Nevertheless, ITO-free solar cells reaching ~77% PCE compared to ITO reference devices are fabricated. Concomitantly, the benefits and drawbacks of this transparent nanomesh electrode are identified, which is of high relevance for future ITO replacement strategies.

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“…More details have been published elsewhere. 23 The EQE measurements were performed under both dark and white light bias conditions at short circuit and under À4 V bias conditions. The total reflectance and transmission spectra were measured by placing the sample at a port of the integrating sphere and illuminating it through the glass substrate.…”

Section: Solar Cell Fabrication and Characterizationmentioning

confidence: 99%

The role of colloidal plasmonic nanostructures in organic solar cells

Singh

Honold

Gujar

et al. 2016

Phys. Chem. Chem. Phys.

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Plasmonic particles can contribute via multiple processes to the light absorption process in solar cells. These particles are commonly introduced into organic solar cells via deposition techniques such as spin-coating or dip-coating. However, such techniques are inherently challenging to achieve homogenous surface coatings as they lack control of inter-particle spacing and particle density on larger areas. Here we introduce interface assisted colloidal self-assembly as a concept for the fabrication of well-defined macroscopic 2-dimensional monolayers of hydrogel encapsulated plasmonic gold nanoparticles. The monolayers showed a pronounced extinction in the visible wavelength range due to localized surface plasmon resonance with excellent optical homogeneity. Moreover this strategy allowed for the investigation of the potential of plasmonic monolayers at different interfaces of P3HT:PCBM based inverted organic solar cells. In general, for monolayers located anywhere underneath the active layer, the solar cell performance decreased due to parasitic absorption. However with thick active layers, where low hole mobility limited the charge transport to the top electrode, the plasmonic monolayer near that electrode spatially redistributed the light and charge generation close to the electrode led to an improved performance. This work systematically highlights the trade-offs that need to be critically considered for designing an efficient plasmonically enhanced organic solar cell.

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Influence of Electron Extracting Interface Layers in Organic Bulk‐Heterojunction Solar Cells

Cited by 8 publications

References 50 publications

Does Electron Delocalization Influence Charge Separation at Donor–Acceptor Interfaces in Organic Photovoltaic Cells?

Does Electron Delocalization Influence Charge Separation at Donor–Acceptor Interfaces in Organic Photovoltaic Cells?

Plasmonic nanomeshes: their ambivalent role as transparent electrodes in organic solar cells

The role of colloidal plasmonic nanostructures in organic solar cells

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