Breakdown and Protection of ALD Moisture Barrier Thin Films

Nehm, Frederik; Klumbies, Hannes; Richter, Claudia; Singh, Aarti; Schroeder, Uwe; Mikolajick, Thomas; Mönch, Tobias; Hoßbach, Christoph; Albert, Matthias; Bartha, Johann W.; Leo, Karl; Müller‐Meskamp, Lars

doi:10.1021/acsami.5b06891

Cited by 48 publications

(39 citation statements)

References 23 publications

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“…To further demonstrate the fully flexible OPVs including light trapping elements, the device is protected by a 20 nm flexible AlO x layer at a water vapor transmission rate (WVTR) of 2 Â 10 À5 g/m 2 day. 28 Degradation of OPVs with this encapsulation was previously investigated, and AlO x layer still showed similar WVTR value without cracking after 300 bending cycles with the bending radius of 15 mm. 31 To check the stability of the solar cell on the PET substrates, a bending test is performed in the ambient condition.…”

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confidence: 54%

“…For the top encapsulation, an equivalent thin-film is deposited on 125 lm planarised Teonex PEN (Dupont Teijin Films Ltd., UK). In a glovebox, this barrier film is directly laminated onto the OPV devices using a special moisture barrier adhesive film (tesa SE, Germany), 28 which contains a latent getter against lateral oxygen and water diffusion. Current voltage curves are acquired under simulated AM 1.5G sunlight (16S-150 V.3, Solar Light Co., USA) using a Keithley 2400 source measuring unit (SMU).…”

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confidence: 99%

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Flexible, light trapping substrates for organic photovoltaics

Park¹,

Berger

Tang³

et al. 2016

Applied Physics Letters

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Micro-structured organic photovoltaic (OPV) devices on polyethylene terephthalate substrates are produced using direct laser interference patterning (DLIP). The performance of organic solar cells on these substrates is improved by a factor of 1.16, and a power conversion efficiency of 7.70% is achieved. We show that a shorter spatial period of the pattern allows for a stronger light trapping effect in solar cell, as it leads to a longer light path. Moreover, since the patterned structures are located on the outside of the fully encapsulated OPV devices, there are no problems with the roughness induced shunts.

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confidence: 54%

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confidence: 99%

Flexible, light trapping substrates for organic photovoltaics

Park¹,

Berger

Tang³

et al. 2016

Applied Physics Letters

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“…Details are described elsewhere. [ 38 ] The ALD deposition takes place either on the planarized Teonex PEN (pPEN, DupontTeijin, Japan) or directly on top of the solar cell cathode. Solar cells are prepared according to the following procedure: First, the PEDOT:PSS "P VP AI 4083" (Heraeus Clevios, Germany) is spin-coated as delivered with 2000 rpm (NOA63/NW35) or 4000 rpm (ITO), heated out at 120 °C for 15 min in air and overnight at 80 °C in an N 2 -fi lled glovebox.…”

Section: Methodsmentioning

confidence: 99%

“…The AlO x layer exhibits water vapor transmission rates down to 3 × 10 −5 g m −2 d −1 , measured at 38 °C and 90% relative humidity (RH). [ 38 ] Current Table 1 .…”

Section: Doi: 101002/aenm201502432mentioning

confidence: 99%

Degradation of Sexithiophene Cascade Organic Solar Cells

Bormann

Nehm

Weiß

et al. 2016

Advanced Energy Materials

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fl exibility or light weight required for fl exible OPV. Atomic layer deposited (ALD) oxide thin-fi lms (e.g. SiO x , AlO x ) provide fl exibility and low WVTR rates at the same time. [22][23][24] This work is motivated by two factors: First, a lifetime study for cascade organic solar cells (CSCs) under ambient climate conditions has not been performed up to now, making the evaluation of their applicability diffi cult. Second, only a few publications show highly effi cient organic solar cells on silver nanowire electrodes. Beyond that, all devices exhibiting a PCE >5% on AgNW electrodes used polymer donors. [25][26][27] In this study, we show aging experiments on organic solar cells with the small molecules α-6T/SubNc/SubPc as cascade. [ 10 ] We compare rigid glass-glass encapsulated devices with ITO bottom electrodes to fully fl exible devices. AgNWs are utilized as transparent electrode, ALD thin-fi lms of alumina serve as fl exible ultra-barrier. The planarization of AgNWs is challenging, as they exhibit high surface roughness which usually causes the organic thin-fi lm device to shunt. Many different planarization techniques have been successfully employed using poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), metal oxides, or small molecules. [ 17,[28][29][30][31][32] Another method uses a peel-off process whereby the silver nanowires are buried in a polymer substrate. [ 25,[33][34][35] We employ the AgNW planarization concept recently demonstrated by Cui et al., [ 36 ] where the AgNWs are buried in the UV-curable optical adhesive "NOA63". This polymer serves as ultrathin and ultrafl exible substrate for the highly conductive AgNW network. Figure 1 shows the electrode fabrication and characterization by means of topographical and optical analysis. Silver nanowires with 35 nm diameter (NW35) are used to transfer the NOA63 into a conductive substrate (details can be found in the Experimental Section).Atomic force microscopy (AFM) measurements reveal that the root-mean-square roughness of the electrode is in the range of 1 to 2 nm (Figure 1 B). Furthermore, the strong phase contrast in Figure 1 C shows that AgNWs protrude from the NOA63 surface. This guarantees an electrical contact to adjacent conductive layers. A sheet resistance ( R S ) of (18.5 ± 0.2) Ω/sq is measured for this electrode even though the maximum processing temperature is only 80 °C. The electrode exhibits a total transmission of 84.5% at a wavelength of 550 nm which is comparable to NW35 on glass. However, plasmonic nanowire absorption, which is already present in the neat glass/NW35 electrode, broadens upon embedding in the polymer. This stronger plasmonic absorption in the spectral region between 350 and 500 nm reduces the average total transmission in the visible light spectrum T av to 82.8% as compared to 83.9% of NW35 on glass. Although ITO on glass exhibits a T av of 84.3%, its R S of 26 Ω/sq is higher than for the NW35 electrode.This ultrasmooth, highly conductive, and transparent AgNW electrode is well suitable for ...

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“…This step is necessary to prevent potential barrier corrosion. 9,10 Aging and WVTR measurements are done in a self-built setup containing thermal insulation boxes with heating resistors in a feedback control system for constant temperature adjustment, silica gel filled plastic boxes to keep the background humidity low, custom circuit boards to connect the samples to a Keithley 2400 source measuring unit (Keithley Instruments, OH, USA), custom-made switching circuits to individually connect samples, and a PC running a self-written measurement software. Each sample is connected to a vial of saturated salt solution, above which a constant relative humidity will arise.…”

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Note: Inhibiting bottleneck corrosion in electrical calcium tests for ultra-barrier measurements

Nehm

Müller‐Meskamp

Klumbies

et al. 2015

Review of Scientific Instruments

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A major failure mechanism is identified in electrical calcium corrosion tests for quality assessment of high-end application moisture barriers. Accelerated calcium corrosion is found at the calcium/electrode junction, leading to an electrical bottleneck. This causes test failure not related to overall calcium loss. The likely cause is a difference in electrochemical potential between the aluminum electrodes and the calcium sensor, resulting in a corrosion element. As a solution, a thin, full-area copper layer is introduced below the calcium, shifting the corrosion element to the calcium/copper junction and inhibiting bottleneck degradation. Using the copper layer improves the level of sensitivity for the water vapor transmission rate (WVTR) by over one order of magnitude. Thin-film encapsulated samples with 20 nm of atomic layer deposited alumina barriers this way exhibit WVTRs of 6 × 10−5 g(H2O)/m2/d at 38 °C, 90% relative humidity.

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Breakdown and Protection of ALD Moisture Barrier Thin Films

Cited by 48 publications

References 23 publications

Flexible, light trapping substrates for organic photovoltaics

Flexible, light trapping substrates for organic photovoltaics

Degradation of Sexithiophene Cascade Organic Solar Cells

Note: Inhibiting bottleneck corrosion in electrical calcium tests for ultra-barrier measurements

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