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Flexible devices often need a protective coating when operating in harmful environments, ranging from mild ambient conditions to a biologically active environment of the human body. The flexibility poses a problem for traditional encapsulation solutions, as those make the device bulky and limit functionality by applying an external casing. Alternatively, fully conformal encapsulation of a device of arbitrary shape can be realized with thin‐film encapsulation (TFE) without altering device dimensions. Yet, TFE is susceptible to fail under mechanical stresses, especially when a hard ceramic coating is applied on a polymer. Reliability of TFE can be enhanced by altering the elasticity of the hard and brittle thin films, by adding softer layers in between sample and barrier. Herein, molecular layer deposited (MLD) metal‐linked trioxysilylheptanoate (M‐TOSH) films are studied for coating of large devices to conformally and uniformly tune the interface between polymer and atomic‐layer‐deposited protective film. The results show that M‐TOSH process scales to large chambers; parameter optimization leads to superior film quality and lowers elastic modulus. Conformality, tested with home‐built macroscopic test device, finds the process suitable for 3D parts. Final testing reveals that ten cycles of MLD interlayer double the crack‐onset‐strain from 0.26% to 0.51%. [ABSTRACT FROM AUTHOR]

Light‐emitting diodes (LEDs) are widely used in lighting and display applications. Carbon quantum dots (CQDs), which have high biocompatibility, high resistance to photobleaching, and full‐spectrum luminescence, have inherent advantages as fluorescent materials for LED devices. Herein, multicolor CQDs are prepared by a new reagent engineering strategy due to the difference of effective conjugate length and the surface electron‐withdrawing groups of CQDs. White CQDs are realized by mixing blue, green, and red CQDs proportionally. Then, the aggregation‐caused quenching phenomenon of CQDs is suppressed through the hydrogen‐bonding network of cellulose nanofibrils (CNFs). Multicolor fluorescent films are prepared from CQDs and CNFs by simple mixing and casting methods. Finally, thin‐film encapsulation based on the photosensitive resin ABPE‐10 coating can be realized and rapidly assembles into fluorescent films with different light‐emitting colors into LED devices, leading to have superior thermal performance compared with conventional LEDs. White LEDs have excellent white‐light illumination performance, with Commission Internationale de L'Eclairage color coordinates of (0.33, 0.37), a correlated color temperature of 5688 K, and a color rendering index of 86. This strategy provides a convenient and scalable pathway for low‐cost, environmentally friendly, and high‐performance CQDs‐based LEDs. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to review the research progress in the realization of the organic–inorganic hybrid thin-film packaging of flexible organic electroluminescent devices using the PEALD (plasma-enhanced atomic layer deposition) and MLD (molecular layer deposition) techniques. Firstly, the importance and application prospect of organic electroluminescent devices in the field of flexible electronics are introduced. Subsequently, the principles, characteristics and applications of PEALD and MLD technologies in device packaging are described in detail. Then, the methods and process optimization strategies for the preparation of organic–inorganic hybrid thin-film encapsulation layers using PEALD and MLD technologies are reviewed. Further, the research results on the encapsulation effect, stability and reliability of organic–inorganic hybrid thin-film encapsulation layers in flexible organic electroluminescent devices are discussed. Finally, the current research progress is summarized, and the future research directions and development trends are prospected. [ABSTRACT FROM AUTHOR]

As the hottest display technology today, OLED devices have been widely used in mobile devices, flexible displays, and other fields. Encapsulation layer film as a protective layer for OLED devices, its current manufacturing technology faces great challenges. The main reason for the challenges is the high cost and low efficiency of current manufacturing technologies. Electrohydrodynamic atomization printing (EHDAP), a low‐cost technology for the rapid manufacture of large‐area films, is up and coming for OLED encapsulation film manufacturing. In this paper, the manufacturing process of EHDAP is investigated for organic layer encapsulation film manufacturing. Multiple spray modes of organic layer encapsulated film solutions were investigated. The effect of printing states in different modes on fabricating organic layer encapsulated films was analyzed. The process phase diagram intervals are given for determining the boundaries of the steady injection state. Further production of organic layer encapsulation film with 95.7% uniformity based on self‐developed printing equipment. The theoretical and experimental studies in this paper pave the way for further development of EHDAP in OLED displays. [ABSTRACT FROM AUTHOR]

Display devices are more and more widely used in mobile devices and wearable devices, which put forward higher lightweight requirements for display devices. The thin film encapsulation (TFE) technology for display panels has emerged. Through the combination of inorganic and organic films, the thin film encapsulation films can provide 10‐6 levels of water vapor barrier ability at the thickness of micrometers, helping the display devices to realize the dual role of lightweight and long lifetime. Organic encapsulation layers prepared by inkjet printing technique with acrylate composition and epoxy composition are commonly used materials in mass production process, which can effectively improve the barrier properties and softness of thin film encapsulation. However, to prepare organic encapsulation films in line with mass production process, it is necessary to achieve high light transmittance, high aging resistance, ultra‐fast curing rate, low volatile level and other functions. In this paper, from the materials perspective of inkjet printing ink, we’ve studied how to realize the multifunctionality of organic encapsulation films through the combination of ink components and the configuration of functional groups, so as to provide reference for the downstream device preparation of organic encapsulation films. By reducing the content of chromogenesis impurities, both acrylic and epoxy based films can achieve high light transmittance (see Fig.8) using inkjet printing film formation method, and the transmittance of visible light (400nm‐800nm) can reach more than 98%. Controlling curing degree above 95% can result in good aging performance (see Table 5&6), and a very low volatile level. (see Fig. 3). [ABSTRACT FROM AUTHOR]

Light‐emitting diodes (LEDs) are widely used in lighting and display applications. Carbon quantum dots (CQDs), which have high biocompatibility, high resistance to photobleaching, and full‐spectrum luminescence, have inherent advantages as fluorescent materials for LED devices. Herein, multicolor CQDs are prepared by a new reagent engineering strategy due to the difference of effective conjugate length and the surface electron‐withdrawing groups of CQDs. White CQDs are realized by mixing blue, green, and red CQDs proportionally. Then, the aggregation‐caused quenching phenomenon of CQDs is suppressed through the hydrogen‐bonding network of cellulose nanofibrils (CNFs). Multicolor fluorescent films are prepared from CQDs and CNFs by simple mixing and casting methods. Finally, thin‐film encapsulation based on the photosensitive resin ABPE‐10 coating can be realized and rapidly assembles into fluorescent films with different light‐emitting colors into LED devices, leading to have superior thermal performance compared with conventional LEDs. White LEDs have excellent white‐light illumination performance, with Commission Internationale de L’Eclairage color coordinates of (0.33, 0.37), a correlated color temperature of 5688 K, and a color rendering index of 86. This strategy provides a convenient and scalable pathway for low‐cost, environmentally friendly, and high‐performance CQDs‐based LEDs.

The purpose of this paper is to review the research progress in the realization of the organic–inorganic hybrid thin-film packaging of flexible organic electroluminescent devices using the PEALD (plasma-enhanced atomic layer deposition) and MLD (molecular layer deposition) techniques. Firstly, the importance and application prospect of organic electroluminescent devices in the field of flexible electronics are introduced. Subsequently, the principles, characteristics and applications of PEALD and MLD technologies in device packaging are described in detail. Then, the methods and process optimization strategies for the preparation of organic–inorganic hybrid thin-film encapsulation layers using PEALD and MLD technologies are reviewed. Further, the research results on the encapsulation effect, stability and reliability of organic–inorganic hybrid thin-film encapsulation layers in flexible organic electroluminescent devices are discussed. Finally, the current research progress is summarized, and the future research directions and development trends are prospected.

Al2O3 and MgO composite (Al2O3/MgO) films were rapidly deposited at low temperatures using filtered cathode vacuum arc (FCVA) technology, aiming to achieve good barrier properties for flexible organic light emitting diodes (OLED) thin-film encapsulation (TFE). As the thickness of the MgO layer decreases, the degree of crystallinity decreases gradually. The 3:2 Al2O3:MgO layer alternation type has the best water vapor shielding performance, and the water vapor transmittance (WVTR) is 3.26 × 10−4 g·m−2·day−1 at 85 °C and 85% R.H, which is about 1/3 of that of a single layer of Al2O3 film. Under the action of ion deposition, too many layers will cause internal defects in the film, resulting in decreased shielding ability. The surface roughness of the composite film is very low, which is about 0.3–0.5 nm depending on its structure. In addition, the visible light transmittance of the composite film is lower than that of a single film and increases with the increase in the number of layers. [ABSTRACT FROM AUTHOR]

As the demand for flexible organic light-emitting diodes (OLEDs) grows beyond that for rigid OLEDs, various elements of OLEDs, such as thin-film transistors, electrodes, thin-film encapsulations (TFEs), and touch screen panels, have been developed to overcome OLEDs' physical and chemical limitations through material and structural design. In particular, TFEs, which protect OLEDs from the external environment, including reactive gases, heat, sunlight, dust, and particles, have technical difficulties to be solved. This review covers various encapsulation technologies that have been developed with the advent of atomic layer deposition (ALD) technology for highly reliable OLEDs, in which solutions to existing technical difficulties in flexible encapsulations are proposed. However, as the conventional encapsulation technologies did not show technological differentiation because researchers have focused only on improving their barrier performance by increasing their thickness and the number of pairs, OLEDs are inevitably vulnerable to environmental degradation induced by ultraviolet (UV) light, heat, and barrier film corrosion. Therefore, research on multi-functional encapsulation technology customized for display applications has been conducted. Many research groups have created functional TFEs by applying nanolaminates, optical Bragg mirrors, and interfacial engineering between layers. As transparent, wearable, and stretchable OLEDs will be actively commercialized beyond flexible OLEDs in the future, customized encapsulation considering the characteristics of the display will be a key technology that guarantees the reliability of the display and accelerates the realization of advanced displays. [ABSTRACT FROM AUTHOR]

Sputtering technique involves the use of plasma that locally heats surfaces of substrates during the deposition of atoms or molecules. This modifies the microstructure by increasing crystallinity and the adhesive properties of the substrate. In this study, the effect of sputtering on the microstructure of parylene-C was investigated in an aluminum nitride (AlN)-rich plasma environment. The sputtering process was carried out for 30, 45, 90 and 120 min on a 5 μm thick parylene-C film. Topography and morphology analyses were conducted on the parylene-C/AlN bilayers. Based on the experimental data, the results showed that the crystallinity of parylene-C/AlN bilayers was increased after 30 min of sputtering and remained saturated for 120 min. A scratch-resistance test conducted on the bilayers depicted that a higher force is required to delaminate the bilayers on top of the substrate. Thus, the adhesion properties of parylene-C/AlN bilayers were improved on glass substrate by about 17% during the variation of sputtering time. [ABSTRACT FROM AUTHOR]

High-performance submicron thin-film encapsulation deposited rapidly under low temperature plays an important role in Si-based organic micro-displays. In this letter, the formation mechanism of high-performance encapsulation films consisting of SiO2/in situ plasma oxidized Al at 77 °C is explained. We think that the reason why the performance of encapsulation films deposited by this method behave better than the simple stacking of SiO2/Al2O3 is the formation of Alâ€"Oâ€"Si bonds. By further optimizing the process parameters, the water vapor transmission rate and the transmittance in the visible region have been improved, which reached 10âˆ'6 g∙mâˆ'2∙dâˆ'1 and 90%, respectively. [ABSTRACT FROM AUTHOR]

Nowadays, flexible organic light-emitting diodes (OLEDs) have been widely used in next-generation wearable electronics. Flexible electrodes, flexible substrates, and flexible encapsulation are indispensable components for the construction of flexible OLEDs. In this review, metal nanowires and graphene-based flexible electrodes, textile (fiber and fabric), novel polymer film-based flexible OLEDs, including the key process of planarization for flexible OLEDs fabrication on uneven surfaces are discussed. OLEDs cannot operate stably without encapsulation in an ambient atmosphere. Not only barrier performance but also mechanical properties are necessary for the encapsulation of flexible OLEDs. The encapsulation technologies for flexible OLEDs fabrication are also described. [ABSTRACT FROM AUTHOR]

Al2O3 and MgO composite (Al2O3/MgO) films were rapidly deposited at low temperatures using filtered cathode vacuum arc (FCVA) technology, aiming to achieve good barrier properties for flexible organic light emitting diodes (OLED) thin-film encapsulation (TFE). As the thickness of the MgO layer decreases, the degree of crystallinity decreases gradually. The 3:2 Al2O3:MgO layer alternation type has the best water vapor shielding performance, and the water vapor transmittance (WVTR) is 3.26 × 10−4 g·m−2·day−1 at 85 °C and 85% R.H, which is about 1/3 of that of a single layer of Al2O3 film. Under the action of ion deposition, too many layers will cause internal defects in the film, resulting in decreased shielding ability. The surface roughness of the composite film is very low, which is about 0.3–0.5 nm depending on its structure. In addition, the visible light transmittance of the composite film is lower than that of a single film and increases with the increase in the number of layers.

The stability of long-term microfabricated implants is hindered by the presence of multiple water diffusion paths within artificially patterned thin-film encapsulations. Side permeation, defined as infiltration of molecules through the lateral surface of the thin structure, becomes increasingly critical with the trend of developing high-density and miniaturized neural electrodes. However, current permeability measurement methods do not account for side permeation accurately nor quantitatively. Here, a novel optical, magnesium (Mg)-based method is proposed to quantify the side water transmission rate (SWTR) through thin film encapsulation and validate the approach using micrometric polyimide (PI) and polyimide-silicon carbide (PI-SiC) multilayers. Through computed digital grayscale images collected with corroding Mg film microcells coated with the thin encapsulation, side and surface WTRs are quantified. A 4.5-fold ratio between side and surface permeation is observed, highlighting the crucial role of the PI-PI interface in lateral diffusion. Universal guidelines for the design of flexible, hermetic neural interfaces are proposed. Increasing encapsulation's width (interelectrode spacing), creating stronger interfacial interactions, and integrating high-barrier interlayers such as SiC significantly enhance the lateral hermeticity., (© 2024 The Authors. Advanced Materials published by Wiley‐VCH GmbH.)

Gas barrier films are widely used in electronic and packaging applications. They are also critical components of flexible organic light-emitting diodes (FOLEDs) that require high gas barrier performance. Among the various film manufacturing techniques, solution-processed thin-film encapsulation (TFE) represents a low-cost FOLED fabrication method. The nanometer-thick SiN films produced following the vacuum ultraviolet (VUV)-induced densification of solution-processed perhydropolysilazane (PHPS) films in a N2 atmosphere can potentially serve as TFE barrier films. However, the nanometer-thick PHPS densification process has not been examined in sufficient detail. We investigated and discussed the effects of the Si–N bond number, PHPS film composition, and free volume (present in the produced Si–N network) on the VUV-induced PHPS densification process. It was found that VUV irradiation caused rapid hydrogen release and film densification through the formation of Si–N bonds. The results obtained using the X-ray photoelectron spectroscopy and dynamic secondary ion mass spectrometry techniques, and the calculated residual hydrogen ratios, revealed that the film composition was strongly related to the number of residual hydrogen atoms and Si–N bonds. Notably, nanometer-thick PHPS film densification was a relatively slow process, in which the free volume in the Si–N network was considerably reduced by the atomic rearrangement induced by the simultaneous cleavage of several Si–N bonds during VUV irradiation. We believe that the results presented herein can potentially serve as a guideline for developing solution-processed nanometer-thick SiN films with relatively high density and excellent gas barrier performance (that is comparable to that exhibited by vacuum-processed barrier films). [ABSTRACT FROM AUTHOR]

As the demand for flexible organic light-emitting diodes (OLEDs) grows beyond that for rigid OLEDs, various elements of OLEDs, such as thin-film transistors, electrodes, thin-film encapsulations (TFEs), and touch screen panels, have been developed to overcome OLEDs’ physical and chemical limitations through material and structural design. In particular, TFEs, which protect OLEDs from the external environment, including reactive gases, heat, sunlight, dust, and particles, have technical difficulties to be solved. This review covers various encapsulation technologies that have been developed with the advent of atomic layer deposition (ALD) technology for highly reliable OLEDs, in which solutions to existing technical difficulties in flexible encapsulations are proposed. However, as the conventional encapsulation technologies did not show technological differentiation because researchers have focused only on improving their barrier performance by increasing their thickness and the number of pairs, OLEDs are inevitably vulnerable to environmental degradation induced by ultraviolet (UV) light, heat, and barrier film corrosion. Therefore, research on multi-functional encapsulation technology customized for display applications has been conducted. Many research groups have created functional TFEs by applying nanolaminates, optical Bragg mirrors, and interfacial engineering between layers. As transparent, wearable, and stretchable OLEDs will be actively commercialized beyond flexible OLEDs in the future, customized encapsulation considering the characteristics of the display will be a key technology that guarantees the reliability of the display and accelerates the realization of advanced displays.

Flexible top‐emission organic light‐emitting diodes (TOLEDs) with a thin‐film encapsulation (TFE) are of increasing attention to improve the flexibility of foldable smartphone organic light‐emitting diode (OLED) displays. There are inevitable issues to achieve foldable display with smaller folding radius for the future portable display. Herein, the device flexibility is investigated with infolding and outfolding tests with the curvature radius from 2.5 to 0.32 mm. Parylene (1 μm)/silicon nitride (SiNx) (X nm)/parylene (1 μm)/SiNx (X nm) (X = 100, 70, 50, and 30 nm) of TFEs are applied on the TOLEDs. It is found that stable device performances can be achieved at the curvature radius of 0.32 mm after 100 000 cycles infolding testing when the SiNx thickness is 30 nm. The device has significant degradation upon outfolding of 5000 cycles at the same radius of 0.32 mm. Note that, the water vapor transmission rate (WVTR) of the TFT with 30 nm SiNx is higher than the TFE with thicker SiNx (e.g., 50 nm). The flexibility and WVTR can be much improved using four‐stacked TFE with 30 nm SiNx for foldable active‐matrix OLED displays. [ABSTRACT FROM AUTHOR]

Sputtering technique involves the use of plasma that locally heats surfaces of substrates during the deposition of atoms or molecules. This modifies the microstructure by increasing crystallinity and the adhesive properties of the substrate. In this study, the effect of sputtering on the microstructure of parylene-C was investigated in an aluminum nitride (AlN)-rich plasma environment. The sputtering process was carried out for 30, 45, 90 and 120 min on a 5 μm thick parylene-C film. Topography and morphology analyses were conducted on the parylene-C/AlN bilayers. Based on the experimental data, the results showed that the crystallinity of parylene-C/AlN bilayers was increased after 30 min of sputtering and remained saturated for 120 min. A scratch-resistance test conducted on the bilayers depicted that a higher force is required to delaminate the bilayers on top of the substrate. Thus, the adhesion properties of parylene-C/AlN bilayers were improved on glass substrate by about 17% during the variation of sputtering time.

A good packing of flexible electronics is one of the most critical points to ensure its lifetime. However, efficient and straightforward packaging technology is still very challenging. In this work, a new strategy for preparing encapsulation film is reported by "enameling" a fusible glass layer on a polymer membrane. Careful consideration has been given to the materials properties and manufacturing process, and the obtained glass‐coated polymer can combine the advantageous properties of polymers and inorganic materials unconventionally. The encapsulation films show exceptional overall properties, including transparency (<5% optical deterioration), flexibility (radius of curvature: 1.5 mm), and low permeability. The film with 12 µm glass layer exhibits a water vapor transmission rate of 5.7 × 10−4 g m−2 day−1, and an oxygen transmission rate of 1.46 × 10−4 g m−2 day−1, which is 5 and 3 orders of magnitude lower than that of the polymer substrate, respectively. The fabrication process is suitable for roll‐to‐roll manufacturing, showing great advantages over the existing deposition methods like plasma‐enhanced chemical vapor deposition and atomic layer deposition in terms of reducing manufacturing costs and simplifying the process. Therefore, it is a significant contribution to the development of flexible electronics packaging technology. [ABSTRACT FROM AUTHOR]

In this paper, the environmental stability of silicon nitride (SiNx) films deposited at 80 °C by plasma-enhanced chemical vapor deposition was studied systematically. X-ray photoelectron spectroscopy and Fourier transform infrared reflection were used to analyze the element content and atomic bond structure of the amorphous SiNx films. Variation of mechanical and optical properties were also evaluated. It is found that SiNx deposited at low temperature is easily oxidized, especially at elevated temperature and moisture. The hardness and elastic modulus did not change significantly with the increase of oxidation. The changes of the surface morphology, transmittance, and fracture extensibility are negligible. Finally, it is determined that SiNx films deposited at low-temperature with proper processing parameters are suitable for thin-film encapsulation of flexible devices.

Abstract In order to protect a flexible OLED on plastic foil against water from the ambient atmosphere a top and bottom thin-film encapsulation (TFE) is necessary. A TFE stack SiN-OCP-SiN with getter in OCP results in excellent shelf lifetime. However, the getter particles result in light scattering that is lost upon water ingress in the stack. As a result spots of reduced electroluminescence are observed during exposure to the ambient atmosphere that limit the practical lifetime of the device drastically. For the bottom emitting OLED we reduced the getter content in the bottom barrier to a level that does not exhibit visible light scattering. The reduced getter capacity with respect to the top barrier does not result in a lower performance of the bottom barrier due to the lower pinhole density in SiN-ITO with respect to Al-SiN. The projected shelf lifetime at ambient conditions is 10 years. Graphical abstract Image 1 Highlights • Hybrid TFE is applied to flexible OLEDs: PEN-OCP(1) SiN(1) OCP(2) SiN(2)-OLED-SiN(3) OCP(3) SiN(4) OCP(4). • SiN(1) and SiN(4) have comparable number of pinholes, but SiN(2)-anode has much lower pinhole density than cathode-SiN(3). • As a result of 2 the OCP getter content in the bottom barrier can be much lower than in the top barrier. • As a result of 3 a spotless and fully transparent bottom barrier is obtained. • The shelf lifetime of the thin-film encapsulated OLED on foil is more than 10 years at ambient conditions. [ABSTRACT FROM AUTHOR]

We fabricated a highly robust and flexible gas diffusion barrier (GDB) with a multi‐interfacial system. Our GDB film had a nanolaminate (NL) structure composed of 1‐nm‐thick ZnO, Al2O3, and MgO sublayers (ZAM). The ZAM NL single layer exhibits a water vapor transmission rate (WVTR) value of 1.92 × 10−5 g/m2/day. Furthermore, a WVTR value of 3.18 × 10−6 g/m2/day was achieved with a thickness of sub‐500 nm by fabricating stacking structures of 2.5 dyads with organic layers. The multi‐barrier demonstrated mechanical reliability with little WVTR change at a tensile strain of about 1%. The ZAM NL film helps to delay the occurrence of cracking and delamination in barrier films in comparison to previous single‐layer films. Thus, a multi‐interfacial and defect‐decoupled ZAM NL structure was effectively designed considering the transmittance, gas diffusion barrier properties, and flexibility. [ABSTRACT FROM AUTHOR]

A thin‐film Hard‐Coat (HC) layer was investigated for the collective encapsulation and mechanical protection of top‐emission OLED micro displays on wafer‐scale and as an alternative solution to individual glass‐lid protection. The HC is fabricated by UV‐curing process from a silica‐based hybrid polymer synthetized by sol‐gel process. [ABSTRACT FROM AUTHOR]

Abstract: The stability of a perovskite solar cell (PSC) is enhanced significantly by applying a customized thin‐film encapsulation (TFE). The TFE is composed of a multilayer stack of organic/inorganic layers deposited by initiated chemical vapor deposition and atomic layer deposition, respectively, whose water vapor transmission rate is on the order of 10−4 g m−2 d−1 at an accelerated condition of 38 °C and 90% relative humidity (RH). The TFE is optimized, taking into consideration various aspects of thermosensitive PSCs. Lowering the process temperature is one of the most effective methods for minimizing the thermal damage to the PSC during the monolithic integration of the TFE onto PSC. The direct deposition of TFE onto a PSC causes less than 0.3% degradation (from 18.5% to 18.2%) in the power conversion efficiency, while the long‐term stability is substantially improved; the PSC retains 97% of its original efficiency after a 300 h exposure to an accelerated condition of 50 °C and 50% RH, confirming the enhanced stability of the PSC against moisture. This is the first demonstration of a TFE applied directly onto PSCs in a damage‐free manner, which will be a powerful tool for the development of highly stable PSCs with high efficiency. [ABSTRACT FROM AUTHOR]

Side leakage experiments have been performed on the organic interlayer, so-called organic coating for planarization (OCP), in a hybrid thin-film encapsulation (TFE) stack based on two silicon nitride (SiN) barrier layers that was developed for organic light-emitting diodes (OLED). To measure the side leakage into OCP, a metallic Ca thin-film monitor can be used. However, the water uptake capacity of the Ca monitor affects the measurements. Here, we eliminated the contribution of the Ca layer from the measurement by variation of the Ca thickness and by measuring the side leakage until it reaches the Ca layer. For OCP with a water getter inside (5% CaO) the side leakage can be monitored by the loss of scattering of the CaO when it reacts with water to Ca(OH) 2 . This work describes measurements of the rate of side leakage into the OCP layer of the TFE stack, both for plain OCP and for OCP with CaO getter inside. The side leakage curves are used to derive diffusion coefficients. Performing measurements at various climates provides acceleration factors that are relevant for the performance quantification of the TFE stack. The limiting factors on the performance of an unstructured TFE stack as produced in a roll-to-roll (R2R) process are presented. For small OLED devices side leakage would drastically reduce the shelf lifetime but for larger devices the permeation properties of the TFE stack determine the shelf lifetime. [ABSTRACT FROM AUTHOR]

Organic light-emitting diodes degrade rapidly by means of local cathode oxidation when exposed to the ambient atmosphere, resulting in visible non-emissive areas called black spots. High performance inorganic based encapsulations are required to protect the OLED. We have applied a hybrid thin-film encapsulation stack consisting of two inorganic barrier layers of silicon nitride deposited at low temperature with an organic layer in between. The resulting water permeation mechanism into the OLED is solely by means of lateral pinhole-to-pinhole transport. With the application of CaO nanoparticles in the organic layer the lateral water transport rate is reduced and we show that black spot formation in 8 cm 2 OLEDs is delayed by 6000 h at accelerated climate conditions of 60°C/90% relative humidity. This is estimated to correspond to 20 years at ambient conditions. [ABSTRACT FROM AUTHOR]

A zero-stress thin-film encapsulation method was developed to mitigate residual stress. By keeping total residual stress at a minimum, the intrinsic mechanical stability of the encapsulated device was increased. The lifetimes of FOLEDs using the zero-stress encapsulation method were increased by more than 35% compared with conventional encapsulation. [ABSTRACT FROM AUTHOR]

Recently, perovskite solar cells (PSCs) have been attracting attention as the most promising alternative to conventional photovoltaics, mainly due to their high power conversion efficiency (PCE) of 25.7%. However, prior to commercialization, problems with their long-term stability caused by moisture should be solved. Accordingly, encapsulation is a crucial strategy for enhancing the long-term stability of PSCs, meaning a well-established strategy that includes an excellent barrier that protects them from the external environment while minimizing any damage during encapsulation is required. In this study, a room temperature thin-film encapsulation (RT-TFE) strategy is applied by transferring a defect-free thermally grown silicon dioxide nanomembrane (t-SiO 2 NM), which is a well-known superior water molecule barrier, onto the PSCs. The average PCE of the devices decreased by only 0.012% with a standard deviation of 0.4249 during the entire encapsulation process, which was achieved by minimizing any thermal degradation of the photovoltaic components, including the perovskite and hole transport layers. This t-SiO 2 NM successfully protected the PSC from external water molecules in an underwater condition for 31 days at room temperature, which is the longest reported survival time of encapsulated PSCs. As a result, the RT-TFE PSC maintained more than 98% of the initial efficiency. • Demonstrated room temperature thin film encapsulation using thermally grown SiO 2. • Demonstrated encapsulation of perovskite solar cells without thermal decomposition. • The thermally grown silicon dioxide nanomembrane is superior moisture barrier. • The encapsulated perovskite solar cell was stable for 31 days underwater. [ABSTRACT FROM AUTHOR]

Owing to the sensitivity of organic materials to ambient conditions, encapsulation of organic light-emitting diodes (OLEDs) is critical. In this work, Al 2 O 3 film, deposited by atomic layer deposition (ALD) technique, on flexible polyethylene terephthalate (PET) substrate is used as a barrier film. Al 2 O 3 is also deposited directly on OLED as thin-film encapsulation. Electrical Ca tests are used to measure water vapor transfer rate (WVTR) values, and an optimum WVTR value of 9 *10−4 g/m2/day using 43 nm Al 2 O 3 film has been obtained. The related results on five different encapsulation structures for solution-processed OLEDs: (i) glass to glass encapsulation (G2G) as a reference, (ii) glass to barrier film encapsulation (G2B), (iii) glass to direct thin-film encapsulation (G2D), (iv) barrier to barrier film encapsulation (B2B), and (v) barrier to direct thin-film encapsulation (B2D), are evaluated. The operating half-lifetime values of OLEDs with G2B- and G2D-encapsulation are 54% and 82% of the half-lifetime with G2G encapsulation, respectively. The lifetime of flexible OLED devices with B2D encapsulation is also 34% more than that with B2B encapsulation. Based on the bending stress analysis, the estimated critical bending radius for B2B and B2D encapsulation of flexible OLEDs are 16.83 and 7.07 mm, respectively. [Display omitted] • Lifetime evaluation of OLEDs using barrier films and/or thin film encapsulations. • Respective L 50 values for G2B and G2D are 54 and 82% of that for G2G encapsulation. • B2D offers better barrier performance than B2B encapsulation of flexible OLEDs. • Corresponding critical radii for B2B and B2D encapsulation are 16.83 and 7.07 mm. • ALD of Al 2 O 3 at a low temperature (85 °C) for barrier film and encapsulation layer. [ABSTRACT FROM AUTHOR]

Materials that can serve as long-lived barriers to biofluids are essential to the development of any type of chronic electronic implant. Devices such as cardiac pacemakers and cochlear implants use bulk metal or ceramic packages as hermetic enclosures for the electronics. Emerging classes of flexible, biointegrated electronic systems demand similar levels of isolation from biofluids but with thin, compliant films that can simultaneously serve as biointerfaces for sensing and/or actuation while in contact with the soft, curved, and moving surfaces of target organs. This paper introduces a solution to this materials challenge that combines (i) ultrathin, pristine layers of silicon dioxide (SiO2) thermally grown on device-grade siliconwafers, and (ii) processing schemes that allow integration of these materials onto flexible electronic platforms. Accelerated lifetime tests suggest robust barrier characteristics on timescales that approach 70 y, in layers that are sufficiently thin (less than 1 μm) to avoid significant compromises in mechanical flexibility or in electrical interface fidelity. Detailed studies of temperature- and thickness-dependent electrical and physical properties reveal the key characteristics. Molecular simulations highlight essential aspects of the chemistry that governs interactions between the SiO2 and surrounding water. Examples of use with passive and active components in high-performance flexible electronic devices suggest broad utility in advanced chronic implants. [ABSTRACT FROM AUTHOR]

• Dynamic diffusion mechanism of optically monitored water vapor in thin film defects. • Establish the calculation model of regional resistance after eliminating defects. • Enables accurate measurement of spotless water vapor transmission rate of films with different defect spot densities. Optoelectronic devices' organic materials and metal electrodes are highly susceptible to water vapor. The use of a thin-film encapsulation technique is an effective solution. The accurate water vapor transmission rate (WVTR) of thin films, however, is challenging to acquire because of the influence of dust particles in industrial production laboratories. We have developed a low-cost, high accurate optical and electrical combined Ca corrosion test to analyze the permeation at the defects by optical camera and Matlab software, and established a model to eliminate the influence caused by defective spots in the WVTR method for the encapsulated film. We tested the WVTR of aluminum oxide (Al 2 O 3) with different defect spot densities to ensure the accuracy and reliability of this process. The results illustrated that regardless of the sample defect spot density, the WVTR acquired by the test method reported in this paper generally agreed with the spotless WVTR. [ABSTRACT FROM AUTHOR]

A qualitative study of electrical probing through 25 nm thick amorphous Al2O3 barrier layers, made by low temperature ALD, has been developed. It has been found that the effectiveness of probing depends on the metallic layer beneath the oxide barrier. While a 100 nm thick Cr layer does not allow any probing through the oxide, softer metals like Al turn out to be ideal candidates. From a mechanical point-of-view, nano-indentation studies (normal nano-indentation with a Berkovitch indenter) onto Al2O3 films made onto the different metals reveal that their mechanical properties are different. While Al2O3 onto Cr is very stiff, Al2O3 deposited onto Al is softer, allowing electrical probes to reach the metal underneath. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we propose a new selective two-step method of anodization of porous anodic alumina (PAA) for thin-film encapsulation. It is based on the formation of a selectively anodized porous alumina membrane using only photoresist (PR) which offers lots of vertical nanopores as release holes for sacrificial layer etching. This method allows finer patterning in the selective PAA process and reduces the whole process time and cost. Furthermore, it does not leave isolated aluminum (Al) residue during the anodization process, and the deposited Al film is not conformal over the 3-dimensional structure. The key for this new selective anodization method is the technique to form the locally anodized PAA membrane with the masking material PR by two-step anodization. The nanopores in the PAA membrane allow the penetration of plasma gas or etchant into the cavity to release the sacrificial layer underneath. To seal the packaging, a thin-film is deposited over the selectively anodized PAA membrane in a vacuum ambient atmosphere with no detectable internal deposition of the sealing material. Hermetically sealed thin-film vacuum encapsulation using the proposed selective anodization method is demonstrated, and its hermeticity is also monitored through the measurement of the center deflection of the sealing layer. [Copyright &y& Elsevier]

Perovskite solar cells (PSCs) have attracted considerable attention due to their excellent photovoltaic properties, but stability issues have prevented their widespread application. PSCs must be protected by encapsulation to extend their lifetime. Here, we show that perhydropolysilazane (PHPS)-based multilayered encapsulation improves the lifetime of PSCs. The PSCs were encapsulated by converting PHPS into silica under vacuum ultraviolet (UV) irradiation. The PHPS-based multilayer encapsulation method achieved a sandwich structure of PHPS/poly(ethylene terephthalate) (PET)/PHPS with a water vapor transmission rate (WVTR) of 0.92 × 10 -3 gm -2 d -1 (at 37.8 °C and 100% relative humidity). We then performed a reservoir test of the encapsulated PSCs to confirm the moisture stability of the encapsulation based on PHPS/PET/PHPS barrier films. The cell lifetime remained stable even after 1000 h of ambient-temperature operation. Finally, we analyzed the mechanical flexibility of the PHPS/PET/PHPS multibarrier through bending tests. The multibarrier exhibited high mechanical stability with no large increase in WVTR after bending.

Abstract: A new technology for thin-film MEMS encapsulation based on a monocrystalline silicon membrane and interfacial bonding is presented. The thickness of the membrane, used here, is 36μm. It is produced on a dedicated wafer using a further development of the “Advanced Porous Silicon Membrane (APSM)” Process. The membrane wafer is attached on waferlevel to a MEMS wafer by glass-frit bonding. Before and during bonding the membrane is mechanically connected to its substrate by vertical anchors. Finally, the substrate is detached by cracking the anchors. Detaching the substrate is optimized by a variation of the lateral and the vertical anchor geometries. The new encapsulation technology enables a very low sensor height by a hermetically sealed monocrystalline MEMS-Cap while using well known technologies from mass production. Hence, a cost-efficient all-purpose thin-film encapsulation is presented. We demonstrate the new encapsulation technology by a capped absolute pressure sensor. [Copyright &y& Elsevier]

Abstract: We investigate the heat transfer property of thin-film encapsulation (TFE) for organic light-emitting diodes (OLEDs). It is demonstrated that the TFE combined with a flexible heat sink shows better thermal performance, compared with the epoxy-filled glass encapsulation and the conventional glass encapsulation. By way of experiments and simulations, we verify that the multi-heterojunction configuration and the low thermal conductivity of the polymer layer in the TFE film have no impact on the thermal performance. Furthermore, we find through simulations that a significant temperature gradient appears inside the TFE layers only when the thermal conductivity of the polymer is lower than 1×10−3 W/mK. This enables us to perform design optimization of the TFE configuration with relaxed heat dissipation. [ABSTRACT FROM AUTHOR]

A thin-film encapsulation process, featuring low-temperature steps, hermetic sealing (preliminary), and RF-compatible shell, is reported. Uniquely attractive as compared with the existing MEMS packaging approaches is its capability to monolithically package metal microstructures inside a microcavity on chip in one continuous surface-micromachining process. The key for this process is a technique to fabricate a large freestanding porous membrane on chip by postdeposition anodization of thin-film aluminum at room temperature. The porous-alumina membrane allows for the diffusion of gas or liquid etchants through the nanopores to etch away the sacrificial material underneath, freeing the movable microstructures encapsulated inside the cavity. To seal the package, a thin film is deposited over the alumina shell whose nanoscale pores of a high aspect ratio (> 30) do not allow any detectable penetration of the sealing material. The low-temperature (< 300 °C) encapsulation process produced a low-pressure seal (8 torr), monitored by a Pirani pressure gauge that also represents an encapsulated freestanding metal microstructure in the cavity. The thin-film package demonstrated a considerably low RF insertion loss of less than 0.1 dB up to 40 GHz. [ABSTRACT FROM AUTHOR]

In this paper, the environmental stability of silicon nitride (SiNx) films deposited at 80 °C by plasma-enhanced chemical vapor deposition was studied systematically. X-ray photoelectron spectroscopy and Fourier transform infrared reflection were used to analyze the element content and atomic bond structure of the amorphous SiNx films. Variation of mechanical and optical properties were also evaluated. It is found that SiNx deposited at low temperature is easily oxidized, especially at elevated temperature and moisture. The hardness and elastic modulus did not change significantly with the increase of oxidation. The changes of the surface morphology, transmittance, and fracture extensibility are negligible. Finally, it is determined that SiNx films deposited at low-temperature with proper processing parameters are suitable for thin-film encapsulation of flexible devices. [ABSTRACT FROM AUTHOR]

Stretchable barrier films capable of maintaining high levels of moisture- and gas-barrier performance under significant mechanical strains are a critical component for wearable/flexible electronics and other devices, but realization of stretchable moisture-barrier films has not been possible due to the inevitable issues of strain-induced rupturing compounded with moisture-induced swelling of a stretched barrier film. This study demonstrates nanolaminated polymer/metal oxide stretchable moisture-barrier films fabricated by a novel molecular layer deposition (MLD) process of polyamide-2,3 (PA-2,3) integrated with atomic layer deposition (ALD) metal oxide processes and an in situ surface-functionalization technique. The PA-2,3 surface upon in situ functionalization with H 2 O 2 vapor offers adequate surface chemisorption sites for rapid nucleation of ALD oxides, minimizing defects at the PA-2,3/oxide interfaces in the nanolaminates. The integrated ALD/MLD process enables facile deposition and precise structural control of many-layered oxide/PA-2,3 nanolaminates, where the large number of PA-2,3 nanolayers provide high tolerance against mechanical stretching and flexing thanks to their defect-decoupling and stress-buffering functions, while the large number of oxide nanolayers shield against swelling by moisture. Specifically, a nanolaminate with 72 pairs of alternating 2 nm (5 cycles) PA-2,3 and 0.5 nm HfO 2 (five cycles) maintains its water vapor transmission rate (WVTR) at the 10 -6 g/m 2 day level upon 10% tensile stretching and 2 mm-radius bending, a significant breakthrough for the wearable/flexible electronics technologies.

A multilayer thin-film encapsulation process based on the use of Atomic Layer Deposition of Al2O3 for organic light-emitting diodes (OLED) has been presented at the last SID Display Week 2012 by LETI. It is based on the use of a generic stack of the kind Al2O3/organic layer/inorganic layer. When comes the time to evaluate the performances of this stack in severe climatic storage conditions, it turns out that the intrinsic stability of the organic decoupling layer becomes of outmost importance. This work details the behavior of the thin film barrier stack when exposed to 85 °C / 85 %RH climatic conditions. [ABSTRACT FROM AUTHOR]