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While sulfide solid electrolytes such as Na11Sn2PS12 can allow fast transport of Na+ ions, their utilization in solid sodium ion batteries is rather unsuccessful since they are not electrochemically compatible to both high‐voltage cathodes and sodium metal anode. In this work, we devise an effective approach toward realizing solid sodium ion batteries, using the Na11Sn2PS12 electrolyte and slurry‐coated NASICON‐type Na3MnTi(PO4)3@C as high‐voltage cathode, highly beneficial for low processing cost and high content/loading of active cathode matter. We report that through significantly improved integrity of electrolyte‐cathode interface, such solid sodium ion batteries can deliver outstanding cycling and rate performance, with a charge voltage resilience up to 4.1 V, a high cathode discharge capacity of 128.7 mAh g−1 against the Na3MnTi(PO4)3@C in cathode is achieved at 0.05 C, and capacity retention ratio of 82% with a rate of 0.1 C is realized after prolonged cycling at room temperature. Besides, we demonstrate that such a solid sodium ion battery can even perform at a sub‐zero Celsius temperature of −10°C, when the conventional control cell using liquid electrolyte completely fail to function. This work is to offer a dependable avenue in engineering next generation of safe solid ion batteries based on highly sustainable and much cheaper material resources. [ABSTRACT FROM AUTHOR]

While caesium lead bromide (CsPbBr3) is promising for highly stable perovskite solar cells (PSCs), the usual solution-based methods require tedious multistep spin coating processes, which imposes a practical barrier against scaling up to large areas for industrial exploitation. Although sequential vapour deposition (SVD) can meet commercial requirements, these films are limited by high trap density and impure phases, resulting in poor performance of PSCs. Here, we obtained low-trap density and effectively phase-pure CsPbBr3 films (grain size > 3 μm, trap density < 4 × 1015 cm−3) by systematic defect and phase management. With the identification of a molecular ionic liquid from theoretical simulation, we find that such a designer molecule can form multiple bonding interactions with the perovskite phase. This results in significantly enhanced crystallization of the CsPbBr3 phase, and more importantly, effective passivation of well recognized Cs- and Br-vacancy defects. CsPbBr3 PSCs with simplified architecture using carbon as electrodes without hole transport layer (HTL) achieved highest power conversion efficiency (PCE) of up to 11.21% for small area devices (0.04 cm2) and 9.18% for large area devices (1 cm2). The unencapsulated devices exhibited excellent long-term stability, maintaining over 91% of the initial PCE after 100 days in ambient air at a humidity of ∼55%. This work also provides a valuable approach to process phase-pure, low-defect, and large-area inorganic CsPbBr3 perovskite films for efficient and stable optoelectronic devices. [ABSTRACT FROM AUTHOR]

Lead‐free Cs2AgBiBr6 double perovskite has received widespread attention because of its non‐toxicity and high thermal stability. However, intrinsic bromide ion (Br–) migration limits continuous operation of Cs2AgBiBr6‐based perovskite solar cells (PSCs). Herein, an operational and simple strategy is carried out to improve the power conversion efficiency (PCE) and long‐term stability of Cs2AgBiBr6‐based PSCs by introducing 1‐butyl‐1‐methylpyrrolidinium chloride (BMPyrCl) and 1‐butyl‐3‐methylpyridinium chloride (BMPyCl) ionic liquids (ILs). The higher binding energy between Br– in Cs2AgBiBr6 and cation in IL containing pyrrole can inhibit Br– migration effectively, thereby reducing film defects and improving energy level matching. The optimized PCE of 2.22% is obtained for hole transport layer‐free, carbon‐based PSC, which hardly degrades at 40% ± 5% relative humidity and 25 °C for 40 days. This work highlights an effective method to mitigate the halide migration in Cs2AgBiBr6 perovskite, thus providing an effective route in promoting the development of lead‐free double PSCs. [ABSTRACT FROM AUTHOR]

Solution‐processed metal halide perovskites have the advantages of a tunable bandgap, excellent charge transport properties, and suitable exciton binding energy. They therefore emerge as promising semiconductors for efficient perovskite solar cells (PSCs) and bright perovskite light‐emitting diodes (PLEDs). In addition, these devices possess a similar planar–heterojunction architecture, thus novel dual‐functional perovskite light‐emitting solar cells (PLESCs) that can realize electrical‐to‐optical and optical‐to‐electrical conversion on one device are developed. To date, high‐performance PLESCs with 17.2% electroluminescence external quantum efficiency and 25.2% power conversion efficiency are achieved using a holistic optimization approach. However, a comprehensive review focusing on dual‐functional PLESCs with discussion on their development and limitations, remains lacking. Herein, the rapid progress in PLESCs, including 0D quantum dot, 2D Ruddlesden–Popper, and 3D bulk perovskite devices, is reviewed. First, the fundamental understanding of the device structure and working principle of PLESCs is overviewed. Second, the state‐of‐the‐art developments for simultaneously achieving high‐efficiency PSCs and PLEDs, focusing on defect passivation, interface optimization, energy level alignment, and dimensional control, are comprehensively summarized. Finally, the authors offer some perspectives for future trends in the development of promising PLESCs, which can provide guidelines for this emerging field. [ABSTRACT FROM AUTHOR]

All‐inorganic CsPbBr3‐based perovskite solar cells (PSCs) have attracted great attention because of their high chemical and thermal stabilities in ambient air. However, the short‐circuit current density (Jsc) of CsPbBr3‐based PSCs is inadequate under solar illumination because of the wide bandgap, inefficient charge extraction and recombination loss, leading to lower power‐conversion efficiencies (PCEs). It is envisaged that in addition to narrowing the bandgap by alloying, Jsc of the PSCs could be enhanced by effective improvement of electron transportation, suppression of charge recombination at the interface between the perovskite and electron transporting layer (ETL), and tuning of the space charge field in the device. In this work, Nb‐doped SnO2 films as ETLs in the CsPbBr3‐based PSCs have been deposited at room temperature by high target utilization sputtering (HiTUS). Through optimizing the Nb doping level alone, the Jsc was increased by nearly 19%, from 7.51 to 8.92 mA·cm−2 and the PCE was enhanced by 27% from 6.73% to 8.54%. The overall benefit by replacing the spin‐coated SnO2 with sputtered SnO2 with Nb doping was up to 39% increase in Jsc and 62% increase in PCE. Moreover, the PCE of the optimized device showed negligible degradation over exposure to ambient environment (T ˜ 25 °C, RH˜45%), with 95.4% of the original PCE being maintained after storing the device for 1200 h. [ABSTRACT FROM AUTHOR]

The scalability processing of all functional layers in perovskite solar cells (PSCs) is one of the critical challenges in the commercialization of perovskite photovoltaic technology. In response to this issue, a large-area and high-quality gallium-doped tin oxide (Ga-SnO x ) thin film is deposited by direct current magnetron sputtering and applied in CsPbBr 3 all-inorganic PSCs as an electron transport layer (ETL). It is found that oxygen defects of SnO x can be remarkably offset by regulating oxygen flux and acceptor-like Ga doping level, resulting in higher carrier mobility and suitable energy level alignment, which is beneficial in accelerating electron extraction and suppressing charge recombination at the perovskite/ETL interface. At the optimal O 2 flux (12 sccm) and Ga doping level (5%), the device based on sputtered Ga-SnO x ETL without any interface modification shows a power conversion efficiency (PCE) of 8.13%, which is significantly higher than that of undoped SnO x prepared by sputtering or spin coating. Furthermore, a PCE of 5.98% for a device with an active area of 1 cm 2 is obtained, demonstrating great potential in fabricating efficient and stable large-area PSCs.