Perovskite photovoltaics on roll-to-roll coated ultra-thin glass as flexible high-efficiency indoor power generators

The internet of things revolution requires efficient, easy-to-integrate energy harvesting. Here, we report indoor power generation by flexible perovskite solar cells (PSCs) manufactured on roll-to-roll indium-doped tin oxide (ITO)-coated ultra-thin flexible glass (FG) substrates with notable transmittance (>80%), sheet resistance (13 Ω/square), and bendability, surpassing 1,600 bending procedures at 20.5-mm curvature. Optimized PSCs on FG incorporate a mesoporous scaffold over SnO2 compact layers delivering efficiencies of 20.6% (16.7 μW⋅cm−2 power density) and 22.6% (35.0 μW⋅cm−2) under 200 and 400 lx LED illumination, respectively. These represent, to the best of our knowledge, the highest reported for any indoor flexible solar cell technology, surpassing by a 60%–90% margin the prior best-performing flexible PSCs. Specific powers (W/g) delivered by these lightweight cells are 40%–55% higher than their counterparts on polyethylene terephthalate (PET) films and an order of magnitude greater than those on rigid glass, highlighting the potential of flexible FG-PSCs as a key enabling technology for powering indoor electronics of the future

Transparente Hochbarriereschichten auf flexiblen Substraten

Die vorliegende Dissertation befasst sich mit der Bewertung eines Mehrfachschichtmodells für Permeationsbarrieren auf Basis einer detaillierten Charakterisierung der zugrunde liegenden Einzelschichten. Diese sind reaktiv gesputterte Oxidschichten als Barriereschicht und mittels Magnetron-PECVD abgeschiedene siliziumhaltige Plasmapolymerschichten zur Verwendung als Zwischenschicht. Zunächst werden die verschiedenen gesputterten Oxidschichten charakterisiert und verglichen. Die untersuchten Materialien sind Zinkoxid, Siliziumoxid, Zink-Zinn-Oxid, Aluminiumoxid und Titanoxid. Die wirkenden Permeationsmechanismen und die Ursachen für teils deutliche Unterschiede zwischen verschiedenen Materialien werden diskutiert. Während die Sauerstoffpermeation immer durch Punktdefekte in den Schichten bestimmt wird, muss bei der Wasserdampfpermeation von weiteren Permeationsmechanismen ausgegangen werden. Am Beispiel des Zink-Zinn-Oxids und des Aluminiumoxids wird anschließend die Abhängigkeit der Permeationseigenschaften von wesentlichen Prozessparametern wie Sputterleistung, Prozessdruck oder reaktiver Arbeitspunkt untersucht. Im zweiten Teil der Arbeit werden die Plasmapolymerschichten hinsichtlich ihrer Struktur- und Permeationseigenschaften charakterisiert und mit gesputtertem Siliziumoxid verglichen. Die Abhängigkeit der Permeationseigenschaften vom Kohlenstoffgehalt in den Schichten wird untersucht. Anhand der gewonnenen Ergebnisse werden abschließend sowohl die Sputterschichten als auch die mittels Magnetron-PECVD abgeschiedenen Schichten hinsichtlich ihrer Eignung für ein Barrieremehrfachschichtsystem bewertet.The aim of this PhD-thesis is to evaluate a concept for a multilayer permeation barrier by a detailed characterization of the different constituent of the layer stack. The multilayer concept is based on reactively sputtered permeation barrier layers and an interlayer that is deposited by using a magnetron based plasma enhanced chemical vapor deposition (Magnetron-PECVD) process. In the first part of this thesis, different sputtered oxide layers are characterized and compared regarding their structural and surface properties as well as their water vapor and oxygen permeability. These oxide layers include the materials zinc oxide, silicon oxide, zinc-tin oxide, aluminum oxide and titanium oxide. The permeation mechanisms and reasons for significant differences in the water vapor and oxygen transmission rates in the different materials are evaluated and discussed. Oxygen permeation thereby is always dominated by defects in the layers. In contrast to that, additional permeation mechanisms can be assumed for water vapor permeation. The dependence of the gas permeation on sputter process parameters like plasma power, process pressure and reactive sputtering mode is evaluated for zinc-tin oxide and aluminum oxide layers. In the second part of this thesis, plasma polymer layers that are deposited using the Magnetron-PECVD process are characterized regarding their structure and surface roughness. Their water vapor and oxygen permeability is compared to the permeation through reactively sputtered silicon oxide layers. The dependence of the gas permeation on the atomic composition, in particular on the carbon concentration, is evaluated. Finally, both the sputtered oxide layers and the Magnetron-PECVD plasma polymer layers are evaluated regarding their usability in a multilayer stack for high permeation barrier applications

Transparente Hochbarriereschichten auf flexiblen Substraten

Die vorliegende Dissertation befasst sich mit der Bewertung eines Mehrfachschichtmodells für Permeationsbarrieren auf Basis einer detaillierten Charakterisierung der zugrunde liegenden Einzelschichten. Diese sind reaktiv gesputterte Oxidschichten als Barriereschicht und mittels Magnetron-PECVD abgeschiedene siliziumhaltige Plasmapolymerschichten zur Verwendung als Zwischenschicht. Zunächst werden die verschiedenen gesputterten Oxidschichten charakterisiert und verglichen. Die untersuchten Materialien sind Zinkoxid, Siliziumoxid, Zink-Zinn-Oxid, Aluminiumoxid und Titanoxid. Die wirkenden Permeationsmechanismen und die Ursachen für teils deutliche Unterschiede zwischen verschiedenen Materialien werden diskutiert. Während die Sauerstoffpermeation immer durch Punktdefekte in den Schichten bestimmt wird, muss bei der Wasserdampfpermeation von weiteren Permeationsmechanismen ausgegangen werden. Am Beispiel des Zink-Zinn-Oxids und des Aluminiumoxids wird anschließend die Abhängigkeit der Permeationseigenschaften von wesentlichen Prozessparametern wie Sputterleistung, Prozessdruck oder reaktiver Arbeitspunkt untersucht. Im zweiten Teil der Arbeit werden die Plasmapolymerschichten hinsichtlich ihrer Struktur- und Permeationseigenschaften charakterisiert und mit gesputtertem Siliziumoxid verglichen. Die Abhängigkeit der Permeationseigenschaften vom Kohlenstoffgehalt in den Schichten wird untersucht. Anhand der gewonnenen Ergebnisse werden abschließend sowohl die Sputterschichten als auch die mittels Magnetron-PECVD abgeschiedenen Schichten hinsichtlich ihrer Eignung für ein Barrieremehrfachschichtsystem bewertet.The aim of this PhD-thesis is to evaluate a concept for a multilayer permeation barrier by a detailed characterization of the different constituent of the layer stack. The multilayer concept is based on reactively sputtered permeation barrier layers and an interlayer that is deposited by using a magnetron based plasma enhanced chemical vapor deposition (Magnetron-PECVD) process. In the first part of this thesis, different sputtered oxide layers are characterized and compared regarding their structural and surface properties as well as their water vapor and oxygen permeability. These oxide layers include the materials zinc oxide, silicon oxide, zinc-tin oxide, aluminum oxide and titanium oxide. The permeation mechanisms and reasons for significant differences in the water vapor and oxygen transmission rates in the different materials are evaluated and discussed. Oxygen permeation thereby is always dominated by defects in the layers. In contrast to that, additional permeation mechanisms can be assumed for water vapor permeation. The dependence of the gas permeation on sputter process parameters like plasma power, process pressure and reactive sputtering mode is evaluated for zinc-tin oxide and aluminum oxide layers. In the second part of this thesis, plasma polymer layers that are deposited using the Magnetron-PECVD process are characterized regarding their structure and surface roughness. Their water vapor and oxygen permeability is compared to the permeation through reactively sputtered silicon oxide layers. The dependence of the gas permeation on the atomic composition, in particular on the carbon concentration, is evaluated. Finally, both the sputtered oxide layers and the Magnetron-PECVD plasma polymer layers are evaluated regarding their usability in a multilayer stack for high permeation barrier applications

Influence of the applied power on the barrier performance of silicon-containing plasma polymer coatings using a hollow cathode-activated PECVD process

A hollow cathode arc discharge is used for the roll-to-roll deposition of silicon-containing plasma polymer thin films on a polymer substrate. It is found that the fragmentation of the used monomer hexamethyldisiloxane (HMDSO) increases with increasing plasma power. The higher fragmentation was related to a reduced hydrogen content as a result of breaking CH bonds. This allowed for a higher degree of cross-linking. The latter has a positive effect on the barrier performance of the coatings. A hollow cathode arc discharge with separate anode allowed the deposition of a plasma polymer with a water vapor transmission rate (WVTR) of 0.16gm(-2)day(-1) (measured at 38 degrees C and 90% r.h.) on a PET substrate while maintaining a deposition rate of approximately 450nmmmin(-1).</p

Vacuum plasma treatment and coating of fluoropolymer webs - challenges and applications

The copolymer ethylene tetrafluoroethylene (ETFE) combines the favorable properties of both ethylene: good processing behavior like hydrocarbon polymers and tetrafluoroethylene: superior weathering stability, chemical resistance and thermal stability [1], [2]. It has a high optical transmittance from ultra violet to near infrared wavelength range. ETFE is used in architecture, e.g. membrane roofs or facades in stadiums, shopping malls and airports, and photovoltaic modules as front-side encapsulation [3]. However, thin film deposition on fluoropolymer webs faces several critical challenges because of poor mechanical and thermo-mechanical properties, inferior surface quality with respect to roughness, surface energy, and low adhesion of coated layers

Nanostructuring of polymer surfaces by magnetron plasma treatment

Stochastic nanostructured polymer surfaces exhibit superior properties like enhanced antireflective behavior and soil-resistance as well as improved adhesion to adhesives and other coatings. This paper investigates and compares the nanostructure formation on the surface of different widely used polymers by means of a roll-to-roll reactive dual magnetron plasma etching process. The etching process induces formation of stochastic nanostructures on the surfaces. Structure shapes, texture and application relevant properties depend on the composition, morphology and crystallinity of the treated polymers. The impact on optical transmission increase and hydrophobic behavior of the surfaces is discussed. Nanostructured varnish coatings allow surface modification of inorganic surfaces that may not be etched directly in a plasma treatment. This paper therefore characterizes plasma etching of acrylic based varnish coatings on polymer webs. Structure formation is investigated in relation to surface active additive content in varnish material. Finally, outdoor stability of a nanostructured ETFE surface is shown in a 24. month outdoor weathering test in central Europe

Vacuum coating on polymer films for outdoor applications

This paper discusses functionalization of ETFE webs by vacuum roll-to-roll deposition of permeation barrier layers and highly conductive transparent electrodes for outdoor applications. A 100 nm thick gas barrier layer (zinc-tin-oxide – ZTO) and a 60nm thick transparent conductive layer stack(indium-tin-oxide – ITO 25 nm – Ag 10 nm –ITO 25 nm) achieve a water vapor transmission rate of 0.01 g/m²d (at38°C/90% r.h.) and sheet resistance of< 6 Ω/sq on a commercial grade ETFE film. However, the elastic properties of ETFE as well as its creep-behavior require specific attention during roll-to-roll processing and for design of the functional layer stacks. Inconsequence, layer thicknesses and material selection must be balanced between functional performance and the ability to survive deformation of the polymer web. This paper compares functional performance and crack formation under strain load of different layer stacks on both PET and ETFE substrates

Influence of the applied power on the barrier performance of silicon-containing plasma polymer coatings using a hollow cathode-activated PECVD process

A hollow cathode arc discharge is used for the roll-to-roll deposition of silicon-containing plasma polymer thin films on a polymer substrate. It is found that the fragmentation of the used monomer hexamethyldisiloxane (HMDSO) increases with increasing plasma power. The higher fragmentation was related to a reduced hydrogen content as a result of breaking C[BOND]H bonds. This allowed for a higher degree of cross-linking. The latter has a positive effect on the barrier performance of the coatings. A hollow cathode arc discharge with separate anode allowed the deposition of a plasma polymer with a water vapor transmission rate (WVTR) of 0.16 g m−2 day−1 (measured at 38 °C and 90% r.h.) on a PET substrate while maintaining a deposition rate of approximately 450 nm m min−1