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Infrared Absorption Imaging of Water Ingress Into the Encapsulation of (Opto-)Electronic Devices
摘要： Water ingress into the encapsulation of electronic devices is a serious issue, especially for organic and perovskite-based electronics. In order to guide the development of suitable barrier materials and design, a reliable, fast, and non-destructive analysis tool is required. In this work, an imaging setup is presented, which is based on selective infrared (IR) radiation sources and a mid- IR sensitive camera that uses the absorption band of water around 1920 nm and a reference band. This system enables us to monitor the distribution of water concentration inside the packaging of devices and its change over time. Our measurement is capable of detecting the local presence of water down to the mg/m2 concentration range in a wide variety of encapsulation materials. The new tool allows identifying the pathways of moisture ingress into the encapsulation along with the corresponding diffusion coef?cient. Thus, it provides fast and reliable analysis of humidity related failure mechanisms, and consequently helps to improve the design of encapsulation materials and processes.
关键词： optical signal detection,Degradation,organic photovoltaics (PVs),packaging,diffusion processes
更新于2025-09-04 15:30:14
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The role of oxygen doping on elemental intermixing at the PVD-CdS/Cu (InGa)Se <sub/>2</sub> heterojunction
摘要： Elemental intermixing at the CdS/CuIn1?xGaxSe2 (CIGS) heterojunction in thin‐film photovoltaic devices plays a crucial role in carrier separation and thus device efficiency. Using scanning transmission electron microcopy in combination with energy dispersive X‐ray mapping, we find that by controlling the oxygen in the sputtering gas during physical vapor deposition (PVD) of the CdS, we can tailor the degree of elemental intermixing. More oxygen suppresses Cu migration from the CIGS into the CdS, while facilitating Zn doping in the CdS from the ZnO transparent contact. Very high oxygen levels induce nanocrystallinity in the CdS, while moderate or no oxygen content can promote complete CdS epitaxy on the CIGS grains. Regions of cubic Cu2S phase were observed in the Cu‐rich CdCuS when no oxygen is included in the CdS deposition process. In the process‐of‐record sample (moderate O2) that exhibits the highest solar conversion efficiency, we observe a ~26‐nm‐thick Cu‐deficient CIGS surface counter‐doped with the highest Cd concentration among all of the samples. Cd movement into the CIGS was found to be less than 10 nm deep for samples with either high or zero O2. The results are consistent with the expectation that Cd doping of the CIGS surface and lack of Zn diffusion into the buffer both enhance device performance.
关键词： scanning transmission electron microscopy,Cu diffusion,Cu (In,Ga)Se2 photovoltaics,CdS structure,STEM‐EDS mapping
更新于2025-09-04 15:30:14
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Two stage image de-noising by SVD on large scale heterogeneous anisotropic diffused image data
摘要： De-noising of images along with the edge enhancement has always been a challenging task in large scale heterogeneous image data. This paper presents a two stage image de-noising as well as edge enhancement method where in the first stage two copies of input noisy image are created through diffusion. The first copy is got by using anisotropic diffusion method which employ optimal diffusion function while the second copy is generated to improve the sharp edges by applying the combination of inverse heat diffusion and Canny edge detector. In the next stage, the singular value decomposition is applied on the two copies achieved in first stage to reduce the noise and improve the quality of detected edges. The optimal number of significant singular values have been estimated by the analysis of signal to noise ratio of singular value decomposed images of first copy. The singular values extracted from the second copy of the diffused image are superimposed with non decreasing weights from linear weighting function. Finally the sharp edged and noise reduced output image is generated by taking the linear combination of two singular value decomposed images. The performance of the proposed method has been compared with existing methods based on singular value decomposition as well as anisotropic diffusion. The experimental results exhibit that the proposed method efficiently enhances the edges by reducing the noisy significantly.
关键词： Image de-noising,Anisotropic diffusion,Edge enhancement,Singular value decomposition
更新于2025-09-04 15:30:14
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Atomistic Insight into Ion Transport and Conductivity in Ga/Al-Substituted Li <sub/>7</sub> La <sub/>3</sub> Zr <sub/>2</sub> O <sub/>12</sub> Solid Electrolytes
摘要： Garnet-structured Li7La3Zr2O12 is a promising solid electrolyte for next-generation solid-state Li batteries. However, sufficiently fast Li-ion mobility required for battery applications only emerges at high temperatures, upon a phase transition to cubic structure. A well-known strategy to stabilize the cubic phase at room temperature relies on aliovalent substitution; in particular, the substitution of Li+ by Al3+ and Ga3+ ions. Yet, despite having the same formal charge, Ga3+ substitution yields higher conductivities (10?3 S/cm) than Al3+ (10?4 S/cm). The reason of such difference in ionic conductivity remains a mystery. Here we use molecular dynamic simulations and advanced sampling techniques to precisely unveil the atomistic origin of this phenomenon. Our results show that Li+ vacancies generated by Al3+ and Ga3+ substitution remain adjacent to Ga3+ and Al3+ ions, without contributing to the promotion of Li+ mobility. However, while Ga3+ ions tend to allow limited Li+ diffusion within their immediate surroundings, the less repulsive interactions associated with Al3+ ions lead to a complete blockage of neighboring Li+ diffusion paths. This effect is magnified at lower temperatures, and explains the higher conductivities observed for Ga-substituted systems. Overall this study provides a valuable insight into the fundamental ion transport mechanism in the bulk of Ga/Al-substituted Li7La3Zr2O12 and paves the way for rationalizing aliovalent substitution design strategies for enhancing ionic transport in these materials.
关键词： Li-ion conductivity/diffusion,enhanced sampling hybrid Monte Carlo,Molecular Dynamics,GSHMC,Ga/Al-substituted LLZO,Solid electrolytes
更新于2025-09-04 15:30:14