Mechanically robust, ITO-free, 4.8% efficient, all-solution processed organic solar cells on flexible PET foil

Nickel, Felix; Haas, Thomas; Wegner, E.; Bahro, Daniel; Salehin, Sayedus; Kraft, O.; Gruber, Patric A.; Colsmann, Alexander

doi:10.1016/j.solmat.2014.07.005

Cited by 42 publications

(41 citation statements)

References 24 publications

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“…Strain occurs within the plane of the device when stretched or bent (the strain is tensile on the convex surfaces above the neutral plane, and compressive on the concave surfaces below the neutral plane). 169 It is thus possible in principle for a solar cell to retain function even if the electrodes and the active materials are cracked all the way through, as long as the pathways leading to the electrodes are not interrupted. 51 Tensile strains can produce cracks in all layers of the device and concomitant delamination if one layer deforms more than another in response to the same stress.…”

Section: Catastrophic Fracturementioning

confidence: 99%

Mechanical degradation and stability of organic solar cells: molecular and microstructural determinants

Savagatrup

Printz

O’Connor

et al. 2015

Energy Environ. Sci.

222

256

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The mechanical properties of organic semiconductors and the mechanical failure mechanisms of devices play critical roles in the yield of modules in roll-to-roll manufacturing and the operational stability of organic solar cells (OSCs) in portable and outdoor applications. This paper begins by reviewing the mechanical propertiesprincipally stiffness and brittleness-of pure films of organic semiconductors. It identifies several determinants of the mechanical properties, including molecular structures, polymorphism, and microstructure and texture.Next, a discussion of the mechanical properties of polymer-fullerene bulk heterojunction blends reveals the strong influence of the size and purity of the fullerenes, the effect of processing additives as plasticizers, and the details of molecular mixing-i.e., the extent of intercalation of fullerene molecules between the side chains of the polymer. Mechanical strain in principle affects the photovoltaic output of devices in several ways, from strain-evolved changes in alignment of chains, degree of crystallinity, and orientation of texture, to debonding, cohesive failure, and cracking, which dominate changes in the high-strain regime. These conclusions highlight the importance of mechanical properties and mechanical effects on the viability of OSCs during manufacture and in operational environments. The review-whose focus is on molecular and microstructural determinants of mechanical properties-concludes by suggesting several potential routes to maximize both mechanical resilience and photovoltaic performance for improving the lifetime of devices in the near term and enabling devices that require extreme deformation (i.e., stretchability and ultra-flexibility) in the future. Broader contextOrganic solar cells (OSCs) are potentially an inexpensive source of renewable energy that can be manufactured at speeds that dwarf the rate at which wafer-based devices (i.e., silicon) can be fabricated. While low efficiencies of OSCs have historically been regarded as a major roadblock, the performance of this class of printable devices is improving rapidly, and module efficiencies of ten percent now seem possible. The susceptibility of polymer-based active layers to undergo thermally activated phase separation, photochemical damage, and other forms of degradation has motivated large and expanding literature devoted to understanding and improving the long-term stability of modules. Conspicuously absent from the literature, however, is a similar effort directed toward understanding the mechanical properties of organic semiconductors and their effects on the lifetime of devices against mechanical failure. The principal advantage of OSCs and all printed electronic devices is, nonetheless, roll-to-roll manufacturing on exible substrates. Manufacturing, installation, and use of these devices will thus require substantial mechanical resilience. Moreover, the ability to make devices on ultrathin plastic sheets-necessary to achieve low production energy for whole modules-requires that the acti...

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Section: Catastrophic Fracturementioning

confidence: 99%

Mechanical degradation and stability of organic solar cells: molecular and microstructural determinants

Savagatrup

Printz

O’Connor

et al. 2015

Energy Environ. Sci.

222

256

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“…The 150 nm thick bottom electrodes were doctor bladed from the PEDOT:PSS formulation Clevios HY E (Heraeus Deutschland GmbH & Co. KG), including dispersed AgNWs in air on a hot plate (65 °C) by using a universal thin‐film applicator (Zehntner ZUA 2000) with an applicator gap of 220 μm. During layer deposition, the applicator was accelerated from 10 to 80 mm s −1 to compensate the solution mass loss, which would otherwise lead to continuously decreasing layer thicknesses in the direction of coating . The PEDOT:PSS:AgNW‐coated and patterned PET substrates were flattened by hot‐pressing using an imprint tool (CNI, NIL Technology) and the temperature and pressure profiles are depicted in Figure b.…”

Section: Methodsmentioning

confidence: 99%

“…Complying with industrially relevant layer‐deposition processes, we doctor bladed the photoactive layer onto 2.5×7.5 cm 2 PET substrates, each carrying 18 devices of 0.22 cm 2 each on top of the optimized bottom HYE as depicted in Figure a. By accelerating the coating bar during the layer deposition, we produced a wedge‐shaped absorber layer on top of the electrode array . The thickness gradient becomes visible in the interferences of the reflected light in the photograph in Figure b.…”

Section: All‐solution‐processed Solar Cellsmentioning

confidence: 99%

Hot‐Pressed Hybrid Electrodes Comprising Silver Nanowires and Conductive Polymers for Mechanically Robust, All‐Doctor‐Bladed Semitransparent Organic Solar Cells

et al. 2018

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Future low‐cost, high‐throughput production of organic solar cells in roll‐to‐roll printing processes calls for all‐solution‐processable device architectures. Mechanical flexibility and robustness are mandatory to roll the solar foils during printing and to eventually comply with certain end‐user requirements. Here, we report on semitransparent organic solar cells, comprising top and bottom silver nanowire (AgNW) electrodes that were embedded into conductive poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). The devices exhibited excellent robustness in bending experiments with radii of 5 and 2.5 mm as well as upon folding. To avoid short circuits from nanowires that could stick out of the bottom electrodes, the PEDOT:PSS:AgNW layers were flattened by hot‐pressing after deposition. All solar cells were fabricated in air by doctor blading and exhibited a clear (haze‐free) transparency due to the absence of bus bars. On photoactive areas of 0.5 cm2, power conversion efficiencies of 3.8 % were obtained.

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“…PEDOT:PSS is also commonly used as a protective layer for the active layer from damaging by the solvent of metal NWs. In addition, the strong bonding between PEDOT and metal NWs helps the formation of excellent electrical contact, which has successfully demonstrated as the top electrode of OSCs . Through the combination of strategies of fabricating metal transparent electrode as the bottom and top transparent electrodes, the fully solution‐processed semitransparent OSCs have also demonstrated …”

Section: The Front Metal Electrodementioning

confidence: 99%

Emerging Novel Metal Electrodes for Photovoltaic Applications

Ren

Ouyang

et al. 2018

Small

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Emerging novel metal electrodes not only serve as the collector of free charge carriers, but also function as light trapping designs in photovoltaics. As a potential alternative to commercial indium tin oxide, transparent electrodes composed of metal nanowire, metal mesh, and ultrathin metal film are intensively investigated and developed for achieving high optical transmittance and electrical conductivity. Moreover, light trapping designs via patterning of the back thick metal electrode into different nanostructures, which can deliver a considerable efficiency improvement of photovoltaic devices, contribute by the plasmon-enhanced light-mattering interactions. Therefore, here the recent works of metal-based transparent electrodes and patterned back electrodes in photovoltaics are reviewed, which may push the future development of this exciting field.

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Mechanically robust, ITO-free, 4.8% efficient, all-solution processed organic solar cells on flexible PET foil

Cited by 42 publications

References 24 publications

Mechanical degradation and stability of organic solar cells: molecular and microstructural determinants

Mechanical degradation and stability of organic solar cells: molecular and microstructural determinants

Hot‐Pressed Hybrid Electrodes Comprising Silver Nanowires and Conductive Polymers for Mechanically Robust, All‐Doctor‐Bladed Semitransparent Organic Solar Cells

Emerging Novel Metal Electrodes for Photovoltaic Applications

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