Due to the severe volume expansion and poor cycle stability, transition metal oxide anode is still not meeting the commercial utilization. We herein demonstrate the synthetic method of core-shell pomegranate-shaped Fe2O3/C nano-composite via one-step hydrothermal process for the first time. The electrochemical performances were measured as anode material for Li-ion batteries. It exhibits excellent cycling performance, which sustains 705 mAh g−1 reversible capacities after 100 cycles at 100 mA g−1. The anodes also showed good rate stability with discharge capacities of 480 mAh g−1 when cycling at a rate of 2000 mA g−1. The excellent Li storage properties can be attributed to the unique core-shell pomegranate structure, which can not only ensure good electrical conductivity for active Fe2O3, but also accommodate huge volume change during cycles as well as facilitate the fast diffusion of Li ion.
The scientific and effective control of steam wetness in steam turbines is of great significance for improving power generation efficiency. Based on the research status of wet steam, the influence of different surface heating intensity in a stator cascade was studied. The distribution of condensation flow parameters in White cascade under 0-700 kW/m 2 surface heating intensity is calculated. On this basis, the positive heating intensity region was determined and refined to obtain the best heating condition with higher accuracy. The results show that the condensation is restrained and the outlet wetness is decreased as the blade surface heating intensity increases. The steam wetness and droplet diameter in the flow field can be controlled by adding heating intensity. Additionally, at the initial stage of applying heat to the blade, an increasing enthalpy drop occurs, and the entropy increase experiences a decline, while negative effects rapidly emerge if the heating intensity is too high. The optimum heating intensity is 120 kW/m 2. Compared with the 0 kW/m 2 , the average outlet wetness, total pressure loss coefficient and entropy increase of 120 kW/m 2 surface heating intensity can be reduced by 1.1266%, 15.5% and 1.7%, respectively, and the enthalpy drop can be increased by 1.7%.
Carbon-based perovskite solar cells (C-PSC) are favored by researchers for their low cost and support for large-scale production. However, the particles precipitated on the surface of the perovskite (PVK) film can affect the fabrication and operation of C-PSC, such as disrupting the coating of C electrode film and producing defects that can aggravate the carrier recombination. Herein a reliable and efficient C-PSC is prepared by applying a physical polishing strategy. The compact interface contact and the larger Fermi level difference at the carbon-perovskite (C/PVK) interface are achieved, resulting in a 21.4% increase in power conversion efficiency compared to that without polishing. A hole-transport-layer-free C-PSC with an efficiency of 12.2% is achieved, resulting from the reduction of perovskite surface roughness and defects that cause non-radiative recombination. It is revealed that the physical polishing can reduce the root mean square roughness from 15.9 nm to 1.2 nm, facilitating the screen printing of the C electrode. The carrier lifetime of the perovskite film also increases from 39.9 ns to 73.3 ns, which improves the photocurrent of the solar cell. We believe that the improved C/PVK interface contact will provide a solid foundation for the future large-scale commercial production of perovskite solar cells.
Sputtered indium tin oxide (ITO) is widely used as top electrode in semi-transparent and tandem perovskite solar cell. However, damage of sputtering to under layers and limited conductivity of ITO are still the two main obstacles that hinder further performance improvement of the devices. In this work, the effects and mechanism of sputtering damage and poor conductivity of ITO are investigated based on a traditional perovskite solar cell with bathocuproine (BCP) buffer layer. In order to suppress the sputtering damage, tin oxide (SnO2) is deposited on C60 to replace BCP buffer layer. However, it is found that the deposition of SnO2 on the non-reactive C60 by atomic layer deposition will result in island growth of SnO2 film, which is the key reason for large dark current in solar cells. Fortunately, the phenomenon is inhibited by decorating C60 surface with WO3 thin film. In order to improve the conductivity of the transparent electrode, an ITO/Au/ITO multilayer architecture is designed. The fill factor (FF) and power conversion efficiency (PCE) of the semi-transparent solar cells (ST-PSCs) with the modified buffer layer and electrodes reached 76.4% and 17.62%, respectively, showing an improvement of FF and PCE when it compared to the device with BCP buffer layer and ITO electrode. It is revealed that the optimization also benefits for the increase of short circuit current of the solar cells. These results provide new strategies for damage reduction of sputtering and performance improvement of ST-PSCs.
With the development of optoelectronic devices toward miniaturization, flexibility, and large-scale integration, conventional submillimeter rigid encapsulation techniques rarely achieve conformational functionality while blocking water and oxygen. At the same time, the sensitivity of electronic devices with organic/metal/semiconductor components to humidity and oxygen severely impairs their operational stability and lifetime. Here, a nanometer to micrometer scale organic/inorganic hybrid thin film encapsulation (TFE) with the self-cleaning ability for flexible encapsulation is developed. The water vapor transmittance rate of polyethylene terephthalate substrate coated with the TFE is as low as 1.65 × 10 −4 g m −2 day −1 , and the barrier improvement factor reaches 10 4 at 38 °C and 90% relative humidity. This value is equivalent to 9.81 × 10 −6 g m −2 day −1 at ambient conditions, sufficient to improve the lifetime of water-sensitive electronic devices. Meanwhile, this TFE shows a super-hydrophobic performance, with a water contact angle of 168.4°. In addition, the resulting barrier films exhibit outstanding optical properties, with an average optical transmittance of 86.88% in the visible region. This versatile TFE can promote the development of optoelectronic devices toward miniaturization and large-scale integration in the future.
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