One-step hydrothermal synthesis of nitrogen and tungsten codoped TiO2 nanorods with high visible light photocatalytic activity

N,W codoped TiO 2 $\mathrm{TiO}_{2}$ nanorods were synthesized via a one-step hydrothermal method using ammonium metatungstate as the nitrogen and tungstate sources. The prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–visible diffuse reflectance spectroscopy (DRS), and X-ray photoelectron spectroscopy (XPS). The results indicated that the N,W codoped TiO 2 $\mathrm{TiO}_{2}$ nanorods exhibited a higher photocatalytic activity under visible light irradiation compared with P25 and undoped TiO 2 $\mathrm{TiO}_{2}$ , because the codoping of N and W ions not only extended the visible light absorption but also promoted the separation of the photogenerated electrons and holes.     

3.3MeV直线感应加速器的设计和性能

综述3.3MeV直线感应加速器(LIA)的物理工程概貌和束流特性参数测量。所测数据均达到或超过了设计指标。并已成功地做为曙光一号自由电子激光器出光实验的电子束源。目前,拟串接更多的加速组元使加速器的电子束能量达到10MeV,以便同时用于自由电子激光研究和闪光X射线照相。     

Interfacial Engineering for Efficient Low-Temperature Flexible Perovskite Solar Cells

Photovoltaic technology with low weight, high specific power in cold environments, and compatibility with flexible fabrication is highly desired for near-space vehicles and polar region applications. Herein, we demonstrate efficient low-temperature flexible perovskite solar cells by improving the interfacial contact between electron-transport layer (ETL) and perovskite layer. We find that the adsorbed oxygen active sites and oxygen vacancies of flexible tin oxide (SnO₂) ETL layer can be effectively decreased by incorporating a trace amount of titanium tetrachloride (TiCl₄). The effective defects elimination at the interfacial increases the electron mobility of flexible SnO₂ layer, regulates band alignment at the perovskite/SnO₂ interface, induces larger perovskite crystal growth, and improves charge collection efficiency in a complete solar cell. Correspondingly, the improved interfacial contact transforms into high-performance solar cells under one-sun illumination (AM 1.5G) with efficiencies up to 23.7 % at 218 K, which might open up a new era of application of this emerging flexible photovoltaic technology to low-temperature environments such as near-space and polar regions.     

Crystallization Regulation by Self-Assembling Liquid Crystal Template Enables Efficient and Stable Perovskite Solar Cells

It is found that the disordered growth of bottom perovskite film deteriorates the buried interface of perovskite solar cells (PSCs), so developing a new material to modify the buried interface for regulating the crystal growth and defect passivation is an effective approach for improving the photovoltaic performance of PSCs. Here, we developed a new ionic liquid crystal (ILC, 1-Dodecyl-3-methylimidazolium tetrafluoroborate) as both crystal regulator and defect passivator to modify the buried interface of PSCs. The high lattice matching between this ILC and perovskite promotes preferential growth of perovskite film along [001] direction, while the oriented ILC with mesomorphic phase has a strong chemical interaction with perovskite to passivate the interface defect, as a result, the modified buried interface exhibits suppressed defects, improved band alignment, reduced nonradiative recombination losses, and enhanced charge extraction. The ILC-modified PSC delivers a power conversion efficiency of 24.92 % and maintains 94 % of the original value after storage in ambient for 3000 h.     

Managing Multiple Halide-Related Defects for Efficient and Stable Inorganic Perovskite Solar Cells

Halide-related surface defects on inorganic halide perovskite not only induce charge recombination but also severely limit the long-term stability of perovskite solar cells. Herein, adopting density functional theory calculation, we verify that iodine interstitials (I_i) has a low formation energy similar to that of the iodine vacancy (V_I) and is also readily formed on the surface of all-inorganic perovskite, and it is regarded to function as an electron trap. We screen a specific 2,6-diaminopyridine (2,6-DAPy) passivator, which, with the aid of the combined effects from halogen-N_pyridine and coordination bonds, not only successfully eliminates the I_i and dissociative I₂ but also passivates the abundant V_I. Furthermore, the two symmetric neighboring -NH₂ groups interact with adjacent halides of the octahedral cluster by forming hydrogen bonds, which further promotes the adsorption of 2,6-DAPy molecules onto the perovskite surface. Such synergetic effects can significantly passivate harmful iodine-related defects and undercoordinated Pb²⁺, prolong carrier lifetimes and facilitate the interfacial hole transfer. Consequently, these merits enhance the power-conversion efficiency (PCE) from 19.6 % to 21.8 %, the highest value for this type of solar cells, just as importantly, the 2,6-DAPy-treated CsPbI_3−xBr_x films show better environmental stability.     

Recoverable Flexible Perovskite Solar Cells for Next-Generation Portable Power Sources

Flexible perovskite solar cells (FPSCs) with excellent recoverability show a wide range of potential applications in portable power sources. The recoverability of FPSCs requires outstanding bendability of each functional layer, including the flexible substrates, electrodes, perovskite light absorbers, and charge transport materials. This review highlights the recent progress and practical applications of high-recoverability FPSCs, and illustrates the routes toward improvement of the recoverability and environmental stability through the choice of flexible substrates and the preparation of high-quality perovskite films, as well as the optimization of charge-selective contacts. In addition, we explore the intrinsic properties of each functional layer from the physical perspective and analyze how to select suitable functional layers. Additionally, some effective strategies are summarized, including material modification engineering of selective contacts, additives and interface engineering of interlayers, which can release mechanical stress and increase the power-conversion efficiency (PCE) and recoverability of the FPSCs. The challenges of making high-performance FPSCs with long-term stability and high recoverability are discussed. Finally, future applications and perspectives for FPSCs are discussed, aiming to promote more extensive commercialization processes for lightweight and durable FPSCs.