Increasing the Fill Factor of Inverted P3HT:PCBM Solar Cells Through Surface Modification of Al‐Doped ZnO via Phosphonic Acid‐Anchored C60 SAMs

Stubhan, Tobias; Salinas, Michael; Ebel, Alexander; Krebs, Frederik C.; Hirsch, Andreas; Halik, Marcus; Brabec, Christoph J.

doi:10.1002/aenm.201100668

Cited by 119 publications

(111 citation statements)

References 24 publications

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“…ethanolamine, methanol and ethanol) was reported to improve the contact properties. 19,30,31 The most popular interfacial dipole layers reported were self-assembled monolayers (SAMs), 32,33 conjugated polyelectrolytes (CPEs) 21,[34][35][36] or polyelectrolyte layers (PEs), 37 which all enhanced the power efficiency of OSCs by reducing the work function difference between MeO x and PCBM and further by reducing defect or trap-assisted recombination at the interface.…”

Section: 26-29mentioning

confidence: 99%

A solution-processed barium hydroxide modified aluminum doped zinc oxide layer for highly efficient inverted organic solar cells

Zhang

Stubhan

et al. 2014

J. Mater. Chem. A

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Inverted organic solar cells (iOSCs) with air stable interface materials and top electrodes and an efficiency of 6.01% are achieved by inserting a barium hydroxide (Ba(OH) 2 ) layer between the aluminum doped zinc oxide (AZO) electron extraction layer and the active layer. A low bandgap diketopyrrolopyrrolequinquethiophene alternating copolymer (pDPP5T-2) and phenyl-C61-butyric acid methyl ester (PC 61 BM) were chosen as the active layer compounds. Compared to the control device without Ba(OH) 2 , insertion of a few nm thick Ba(OH) 2 layer results in an enhanced V OC of 10%, J SC of 28%, FF of 28% and PCE of 80%. Modification of AZO with a solution processed low-cost Ba(OH) 2 layer increased the efficiency of the inverted device by dominantly reducing the energy barrier for electron extraction from PC 61 BM, and consequently, reduced charge recombination is observed. The drastic improvement in device efficiency and the simplicity of fabrication by solution processing suggest Ba(OH) 2 as a promising and practical route to reduce interface induced recombination losses at the cathode of organic solar cells.

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Section: 26-29mentioning

confidence: 99%

A solution-processed barium hydroxide modified aluminum doped zinc oxide layer for highly efficient inverted organic solar cells

Zhang

Stubhan

et al. 2014

J. Mater. Chem. A

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“…SAMs of functionalized fullerenes have been used in organic photovoltaics, 13,21,22 memory transistors, 9 light sensors 23 and SAMFETs. 18,24,25 In all of these devices the order of the SAM is of crucial importance for electronic properties.…”

Section: Introductionmentioning

confidence: 99%

“…By varying the mixing ratio, a continuous shift of the properties can be obtained, as exemplarily shown for the threshold voltage in organic thin film transistors. 10 Due to this large variety in scope for design, SAMs have been successfully integrated into various organic electronic devices, such as organic thin film transistors (TFTs), 11,12 organic photovoltaics (OPV) 13 and organic memory devices. 9,14 Even semiconducting properties can be included in the molecules, which leads to organic semiconducting monolayers.…”

Section: Introductionmentioning

confidence: 99%

Tuning the molecular order of C₆₀-based self-assembled monolayers in field-effect transistors

Schmaltz¹,

Khassanov²,

Steinrück

et al. 2014

Nanoscale

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The control of order in organic semiconductor systems is crucial to achieve desired properties in electronic devices. We have studied the order in fullerene functionalized self-assembled monolayers by mixing the active molecules with supporting alkyl phosphonic acids of different chain length. By adjusting the length of the molecules, structural modifications of the alignment of the C 60 head groups within the SAM can be tuned in a controlled way. These changes on the sub-nanometre scale were analysed by grazing incidence X-ray diffraction and X-ray reflectivity. To study the electron transport properties across these layers, self-assembled monolayer field-effect transistors (SAMFETs) were fabricated containing only the single fullerene monolayer as semiconductor. Electrical measurements revealed that a high 2D crystalline order is not the only important aspect. If the fullerene head groups are too confined by the supporting alkyl phosphonic acid molecules, defects in the crystalline C 60 film, such as grain boundaries, start to strongly limit the charge transport properties. By close interpretation of the results of structural investigations and correlating them to the results of electrical characterization, an optimum chain length of the supporting alkyl phosphonic acids in the range of C 10 was determined. With this study we show that minor changes in the order on the sub-nanometre scale, can strongly influence electronic properties of functional self-assembled monolayers.

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“…Mostly the open-circuit voltage (V oc ) or the fill factor (FF) are negatively affected. The low FF often comes along with distorted current-voltage (J-V ) curves in the extreme case showing inflection points close to V oc (so-called S-kink) [6,7,8,9].…”

mentioning

confidence: 99%

Simple experimental test to distinguish extraction and injection barriers at the electrodes of (organic) solar cells with S-shaped current–voltage characteristics

Tress

Inganäs

2013

Solar Energy Materials and Solar Cells

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Adjusting the work function of the two electrodes to the energy levels of the intrinsic active materials of an organic solar cell is crucial for a good device performance. Often, injection barriers (in combination with selective contacts blocking one charge carrier species) caused by a misaligned metal work function or extraction barriers resulting from insulating intentional or unintentional interlayers between metal and active layers, result in a decrease in fill factor seen in the extreme case in S-shaped current–voltage (J–V) characteristics. To avoid this S-kink, it is essential to identify its origin, desirably applying a simple experimental method. We propose an approach based on analyses of current–voltage data as a function of illumination intensity. A normalization of the J–V curves at the saturated photocurrent reveals distinctive features for each type of barrier. We apply the method to planar heterojunction small-molecule and bulk heterojunction polymer solar cells with oxidized metal electrode or plasma-treated active layer and explain the theory with a drift-diffusion model.

Funding Agencies|BMBF (OPEG)|13N9720|Reiner Lemoine foundation||Science Council (V)||Swedish Energy Agency||Knut and Alice Wallenberg Foundation||

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Increasing the Fill Factor of Inverted P3HT:PCBM Solar Cells Through Surface Modification of Al‐Doped ZnO via Phosphonic Acid‐Anchored C60 SAMs

Cited by 119 publications

References 24 publications

A solution-processed barium hydroxide modified aluminum doped zinc oxide layer for highly efficient inverted organic solar cells

A solution-processed barium hydroxide modified aluminum doped zinc oxide layer for highly efficient inverted organic solar cells

Tuning the molecular order of C₆₀-based self-assembled monolayers in field-effect transistors

Simple experimental test to distinguish extraction and injection barriers at the electrodes of (organic) solar cells with S-shaped current–voltage characteristics

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Increasing the Fill Factor of Inverted P3HT:PCBM Solar Cells Through Surface Modification of Al‐Doped ZnO via Phosphonic Acid‐Anchored C60 SAMs

Cited by 119 publications

References 24 publications

A solution-processed barium hydroxide modified aluminum doped zinc oxide layer for highly efficient inverted organic solar cells

A solution-processed barium hydroxide modified aluminum doped zinc oxide layer for highly efficient inverted organic solar cells

Tuning the molecular order of C60-based self-assembled monolayers in field-effect transistors

Simple experimental test to distinguish extraction and injection barriers at the electrodes of (organic) solar cells with S-shaped current–voltage characteristics

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Tuning the molecular order of C₆₀-based self-assembled monolayers in field-effect transistors