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The degradation of sexithiophene cascade organic solar cells is studied. Glass–glass encapsulated devices on indium tin oxide as transparent electrode show efficiencies of 6.6% and degrade within 500 h in illuminated 38 °C/50% RH climate. Fully flexible devices with silver nanowire electrode and alumina barrier achieve 5% efficiency and degrade within 30 h due to electrode failure. [ABSTRACT FROM AUTHOR]

The article offers information on a study which examines ultratransparent poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate)(PEDOT:PSS) and silver (Ag) grid hybrid electrodes for organic photovoltaic (OPV) cells. An oxygen plasma etching process was performed to prepare the PEDOT:PSS thin films. It shows the potential of hybrid electrodes for effective OPV cells.

Highly transparent electrodes are demonstrated based on thermally evaporated calcium:silver blend thin-films, which show unusually high transmission well above the expectations from bulk material properties and thin film optics. These electrodes exhibit a low sheet resistance of 27.3 Ω/, combined with an extraordinarily high mean transmittance of 93.0% in the visible spectral range (σdc/σopt = 186.7), superior to the commonly used inorganic electrodes made from indium tin oxide (ITO). Additionally, the metal blend electrode is flexible, showing a constant sheet resistance down to a bending radius of 10 mm and can be employed on top of organic devices without causing damage to the organic material. The spontaneously formed unique microstructure of a polycrystalline Ag network with randomly distributed nanoapertures, surrounded by a calcium shell, enables broadband transmittance enhancement due to amplified plasmonic coupling. Consequently, top-illuminated organic solar cells using such metal blend electrodes achieve a power conversion efficiency of 7.2% (which defines a new record for top illuminated organic solar cells) and even exceed the efficiency of similar bottom-illuminated reference solar cells (6.9%) employing common ITO electrodes. [ABSTRACT FROM AUTHOR]

The great potential of solution-processed metal nanowire networks utilized as a transparent electrode has attracted much attention in the last years. Typically, silver nanowires are applied, although their replacement by more abundant and cheaper materials is of interest. Here, a hydrazine-free synthesis route for high aspect ratio copper nanowires is used to prepare conductive networks showing an enhanced electrode performance. The network deposition is done with a scalable spray-coating process on glass and on polymer foils. By a pressing or an annealing step, highly conductive transparent electrodes are obtained, and they reveal transmittance-resistance values similar to indium tin oxide (ITO) and networks made of silver nanowires. The application potential of the copper nanowire electrodes is demonstrated by integrating them into an evaporated small-molecule organic solar cell with 3% efficiency. [ABSTRACT FROM AUTHOR]

High performance indium tin oxide (ITO)-free small molecule organic solar cells and organic light-emitting diodes (OLEDs) are demonstrated using optimized ZnO electrodes with alternative non-metallic co-dopants. The co-doping of hydrogen and fluorine reduces the metal content of ZnO thin films, resulting in a low absorption coefficient, a high transmittance, and a low refractive index as well as the high conductivity, which are needed for the application in organic solar cells and OLEDs. While the established metal-doped ZnO films have good electrical and optical properties, their application in organic devices is not as efficient as other alternative electrode approaches. The optimized ZnO electrodes presented here are employed in organic solar cells as well as OLEDs and allow not only the replacement of ITO, but also significantly improve the efficiency compared to lab-standard ITO. The enhanced performance is attributed to outstanding optical properties and spontaneously nanostructured surfaces of the ZnO films with non-metallic co-dopants and their straightforward integration with molecular doping technology, which avoids several common drawbacks of ZnO electrodes. The observations show that optimized ZnO films with non-metallic co-dopants are a promising and competitive electrode for low-cost and high performance organic solar cells and OLEDs. [ABSTRACT FROM AUTHOR]

n‐Doped C60 is reported as a new electrode material for indium‐tin‐oxide‐free organic solar cells. All layers from the bottom to top electrode are prepared in one step in a vacuum chamber. The organic solar cells based on the n‐C60 electrodes assisted by a semitransparent metal grid exhibit efficiencies as high as 2.9%. [ABSTRACT FROM AUTHOR]

We present highly transparent and conductive silver thin films in a thermally evaporated dielectric/metal/dielectric (DMD) multilayer architecture as top electrode for efficient small molecule organic solar cells. DMD electrodes are frequently used for optoelectronic devices and exhibit excellent optical and electrical properties. Here, we show that ultrathin seed layers such as calcium, aluminum, and gold of only 1 nm thickness strongly influence the morphology of the subsequently deposited silver layer used as electrode. The wetting of silver on the substrate is significantly improved with increasing surface energy of the seed material resulting in enhanced optical and electrical properties. Typically thermally evaporated silver on a dielectric material forms rough and granular layers which are not closed and not conductive below thicknesses of 10 nm. With gold acting as seed layer, the silver electrode forms a continuous, smooth, conductive layer down to a silver thickness of 3 nm. At 7 nm silver thickness such an electrode exhibits a sheet resistance of 19 Ω/□ and a peak transmittance of 83% at 580 nm wavelength, both superior compared to silver electrodes without seed layer and even to indium tin oxide (ITO). Top-illuminated solar cells using gold/silver double layer electrodes achieve power conversion efficiencies of 4.7%, which is equal to 4.6% observed in bottom-illuminated reference devices employing conventional ITO. The top electrodes investigated here exhibit promising properties for semitransparent solar cells or devices fabricated on opaque substrates. [ABSTRACT FROM AUTHOR]

Abstract: We have developed semi-transparent n–i–p organic solar cells (OSC) with free-standing multi-wall carbon nanotube (f-CNT) sheets as transparent top electrodes. By a simple and damage-free room temperature orthogonal liquid solution assisted self-laminating process, f-CNT top electrodes are successfully deposited on top of ZnPc:C60 bulk heterojunction small molecule OSCs. The cells show high fill factors above 58% as well as efficiencies up to 1.5% and greater long-term stability compared to the device having a metal electrode. For the given cell structure with f-CNT semi-transparent electrodes, the influence of an optical spacer on light absorption is studied by a systematic variation of the hole transport layer thickness, supported by optical simulations. The results strongly indicate that OSCs with f-CNT top electrodes and optimized thin film stack are highly promising for semi-transparent OSCs, which can be used in tandem devices, in tinted smart windows, and similar applications by a simple and damage-free process in roll-to-roll configuration that can be scaled to large area manufacturing. [Copyright &y& Elsevier]

A hybrid electrode with a combination of an ultratransparent conductive polymer (nearly 100% transparency) and a semitransparent silver grid is developed for organic photovoltaic cells. In article number 1401822, Yong Hyun Kim and co‐workers report that the hybrid electrode shows an improvement of the photovoltaic performance and a potential to reduce a significant resistive power loss in large‐area devices. These hybrid electrodes will contribute the development of low‐cost, efficient, large‐area organic photovoltaic cells. [ABSTRACT FROM AUTHOR]

The cover illustrates a flexible small molecule solar cell with three different semitransparent silverbased top electrodes using varying seed layers. With increasing surface energy of the seed layer, the wetting of subsequently deposited silver is significantly improved as indicated in the zoomed out SEM microscope images. For continuous and closed silver films, the transparency of the electrode, the optical field distribution inside the solar cell, and its power conversion efficiency are strongly increased. Further details can be found in the article by Sylvio Schubert and co‐workers on page 438. [ABSTRACT FROM AUTHOR]

Flexible aluminum moisture barrier films are shown to meet ultra-barrier requirements with water vapor transmission rates as low as 1*10 −4 g/m 2 /day at 38 °C and 90% R.H. These low transmission rates are achieved by lamination of two films that are independently processed on individual substrates. The integration in organic electronic devices like organic solar cells or OLEDs is particularly easy in a single lamination step, since an existing aluminum electrode can be utilized as one half of the moisture barrier. The resulting laminate maintains flexibility of the device and improves the barrier quality by an order of magnitude compared to conventional stacking of two barriers. Organic solar cells with this type of encapsulation are manufactured and aged in controlled climate. They do not exhibit significant extrinsic degradation. [ABSTRACT FROM AUTHOR]

Abstract: We investigate various electrode combinations of bottom and top contacts for organic photovoltaic (OPV) cells. Silver (Ag), indium tin oxide (ITO), poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), and silver nanowires (AgNW) are used as bottom electrodes. As top electrodes, thin silver layers (t-Ag) and free-standing carbon nanotube (f-CNT) sheets are employed. The manufactured zinc phthalocyanine (ZnPc): fullerene C60 small molecule bulk heterojunction OPV cells with different kinds of bottom electrodes show efficiencies of 1.9∼2.2% and 1.1∼1.5%, when comprised of t-Ag and f-CNT top contacts, respectively. We demonstrate alternative electrodes beyond ITO, silver, and aluminum, which can be readily used for organic photovoltaics technology. [Copyright &y& Elsevier]