SnO2 has been the most commonly used electron transport layer (ETL) in perovskite solar cells (PSCs) due to its excellent electron mobility and stability. To meet the applications of SnO2 ETL in large-scale solar cells, a rapid but inexpensive synthesis of high-quality SnO2 film is urgently needed. Herein, SnO2 quantum dots (QDs) were synthesized through a super rapid (∼3 min), additive-free microwave-assisted reaction. Comparing with the crystalized SnO2 films, the small-sized SnO2 QDs present improved electronic properties, including the Fermi level, conductivity, electron mobility, and trap density. Hence, with this SnO2 ETL, the power conversion efficiency of the PSCs reached 20.24% using a CH3NH3PbI3 absorber, which is among the highest values in the same rank. Overall, these results demonstrate a bright future for the facile microwave-assisted synthesis of SnO2 QDs along with their application for highly flexible and efficient PSCs.
A solid composite electrolyte-like bifunctional separator customized for lithium metal batteries, is developed by wrapping a PP substrate with PVDF–DBDPO layers on both sides, enabling high fire resistance and excellent cycling performance.
The SnO2 electron transport layer (ETL) for perovskite solar cells (PSCs) has been recognized as one of the most reported protocols due to its processing convenience, high reproducibility, and excellence in device performance. To date, the thermal annealing (TA) process is still an essential step for a high-quality SnO2 ETL to reduce the surface trap density. This however could restrict its processing with high thermal energy input and set a barrier to the easiness of manufacturing such as processing under room-temperature conditions. Herein, we report a thermal annealing-free (TAF) SnO2 ETL by an alternative UV-ozone (UVO) treatment. This technique simultaneously endows the SnO2 ETL with a deeper valence band maximum (EVB) and lower defect density. Furthermore, with this SnO2 ETL, a power conversion efficiency (PCE) of 21.46 and 22.26% was achieved based on MAPbI3 and Cs0.05(FA0.85MA0.15)0.95Pb(I0.85Br0.15)3 absorbers, respectively. Importantly, a fully room-temperature-processed (RTP) PSC based on the TAF-SnO2 ETL has been demonstrated with a PCE of 20.88% on a rigid substrate and 15.92% on a flexible substrate, which are the highest values for RTP solar cells.
The booming market of portable and wearable electronics has aroused the requests for advanced flexible self-powered energy systems featuring both excellent performance and high safety. Herein, we report a safe, flexible, self-powered wristband system by integrating high-performance zinc-ion batteries (ZIBs) with perovskite solar cells (PSCs). ZIBs were first fabricated on the basis of a defective MnO2–x nanosheet-grown carbon cloth (MnO2–x@CC), which was obtained via the simple lithium treatment of the MnO2 nanosheets to slightly expand the interlayer spacing and generate rich oxygen vacancies. When used as a ZIB cathode, the MnO2–x@CC with a ultrahigh mass loading (up to 25.5 mg cm–2) exhibits a much enhanced specific capacity (3.63 mAh cm–2 at current density of 3.93 mA cm–2), rate performance, and long cycle stability (no obvious degradation after 5000 cycles) than those of the MnO2@CC. Importantly, the MnO2–x@CC-based quasi-solid-state ZIB not only achieves excellent flexibility and an ultrahigh energy density of 5.11 mWh cm–2 (59.42 mWh cm–3) but also presents a high safety under a wide temperature range and various severe conditions. More importantly, the flexible ZIBs can be integrated with flexible PSCs to construct a safe, self-powered wristband, which is able to harvest light energy and power a commercial smart bracelet. This work sheds light on the development of high-performance ZIB cathodes and thus offers a good strategy to construct wearable self-powered energy systems for wearable electronics.
At present, an important research area is the search for materials that are compatible with CMOS technology and achieve a satisfactory response rate and modulation efficiency. A strong local field of graphene surface plasmon polariton (SPP) can increase the interaction between light and graphene, reduce device size, and facilitate the integration of materials with CMOS. In this study, we design a new modulator of SPP-based cycle branch graphene waveguide. The structure comprises a primary waveguide of graphene–LiNbO3–graphene, and a secondary cycle branch waveguide is etched on the surface of LiNbO3. Part of the incident light in the primary waveguide enters the secondary waveguide, thus leading to a phase difference with the primary waveguide as reflected at the end of the branch and interaction coupling to enhance output light intensity. Through feature analysis, we discover that the area of the secondary waveguide shows significant localized fields and SPPs. Moreover, the cycle branch graphene waveguide can realize gain compensation, reduce transmission loss, and increase transmission distance. Numerical simulations show that the minimum effective mode field area is about 0.0130l2, the gain coefficient is about 700 cm–1, and the quality factor can reach 150. The structure can realize the mode field limits of deep subwavelength and achieve a good comprehensive performance.
Abstract Herein, the authors report the fabrication of copper oxide/manganese oxide (CuO/Mn 3 O 4 ) hierarchical arrays on Cu substrate via an oriented catalytic oxidation combined with subsequent annealing. Based on an ingenious oriented catalytic oxidation process, abundant CuO/Mn 3 O 4 nanosheets are directionally modified on the surface of Cu(OH) 2 nanorod arrays which are uniformly grown on the Cu substrate. Through subsequent annealing treatment in an N 2 atmosphere, CuO/Mn 3 O 4 nanorod arrays are fabricated with tuned oxygen vacancies. The 3D hybrid nanoarray structure with advantages of enhanced electron transfer, a large exposed surface area, and robust structure stability can address the drawbacks associated with bare CuO electrodes. As a result, the as‐prepared CuO/Mn 3 O 4 nanoarray electrode demonstrates excellent electrochemical performance, delivering a high specific capacitance of 433 mF cm −2 at 5 mA cm −2 (1732 F g −1 at 20 A g −1 ), and achieving a long cycling lifespan with 144% capacitance retention at 20 mA cm −2 after 20 000 cycles. Interestingly, this facile oriented catalytic oxidation strategy can be extended to prepare other metal oxides/hydroxides (Ni 2+ , Co 2+ , Cu 2+ , Zn 2+ , or mixed ions based) on the surface of Cu(OH) 2 nanorod templates respectively, manifesting its versatility for preparing CuO‐based hybrid nanorod arrays on the Cu substrate.
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