An Organic-Inorganic Hybrid Electrolyte as a Cathode Interlayer for Efficient Organic Solar Cells.

An organic-inorganic hybrid electrolyte based on a cyclic Ti-oxo cluster as the inorganic core and naphthalene-based organic ammonium bromide salts as the electrolyte was developed with easy synthesis and low cost. The new hybrid electrolyte exhibits excellent solubility in methanol, aligned work function, good conductivity, and amorphous state in thin film, enabling its successful application as a cathode interlayer in organic solar cells with a high power conversion efficiency of 17.19 %. This work demonstrates that the hybrid electrolytes are a new kind of semiconductor, exhibiting promising applications in organic electronics.

Methylamine-Dimer-Induced Phase Transition toward MAPbI3 Films and High-Efficiency Perovskite Solar Modules.

Perovskite films prepared with CH3NH2 molecules under ambient conditions have led to rapid fabrication of perovskite solar cells (PSCs), but there remains a lack of mechanistic studies and inconsistencies with operability in their production. Here the crystal structure of CH3NH2-CH3NH3PbI3 was analyzed to involve hydrogen bonds (CH3NH2···CH3NH3+) and has guided the facile, reproducible preparation of high-quality perovskite films under ambient conditions. Hydrogen bonds within CH3NH2···CH3NH3+ dimers were found in the CH3NH2-CH3NH3PbI3 intermediates, accompanied by 1D-PbI3- chains (δ-phase). The weakly hydrogen-bonded CH3NH2 molecules were easily released from the CH3NH2-CH3NH3PbI3 intermediates, contributing to rapid, spontaneous phase transition from 1D-PbI3- (δ-phase) to 3D-PbI3- (α-phase). Further introduction of CH3NH3Cl into the CH3NH2-CH3NH3PbI3 intermediates led to interruption of 1D-PbI3- transition into 0D-Pb2I9-xClx5-(0 < x < 6), adjusting the phase transition route toward 3D-PbI3-. On the basis of the above understanding, CH3NH2 solution in ethanol and CH3NH3Cl were used for precursors and a best efficiency of 20.3% in PSCs was achieved. Large-scale modules (12 cm2 aperture area) fabricated by a dip-coating technology exhibited an efficiency up to 16.0% and outstanding stability over 10 000 s under continuous output. The developed preparation method of perovskite precursors and insightful research into the methylamine-dimer-induced phase transition mechanism have enabled the production of high-quality perovskite films with robust operability, showing great potential for large-scale commercialization.

High-Efficiency, Hysteresis-Less, UV-Stable Perovskite Solar Cells with Cascade ZnO-ZnS Electron Transport Layer.

Perovskite solar cells (PSCs) have reached certified efficiencies of up to 23.7% but suffered from frailness and instability when exposed to ambient atmosphere. Zinc oxide (ZnO), when used as electron transport layer (ETL) on PSCs, gives rise to excellent electronic, optic, and photonic properties, yet the Lewis basic nature of ZnO surface leads to deprotonation of the perovskite layer, resulting in serious degradation of PSCs using ZnO as ETL. Here, we report a simple but effective strategy to convert ZnO surface into ZnS at the ZnO/perovskite interface by sulfidation. The sulfide on ZnO-ZnS surface binds strongly with Pb2+ and creates a novel pathway of electron transport to accelerate electron transfer and reduce interfacial charge recombination, yielding a champion efficiency of 20.7% with improved stability and no appreciable hysteresis. The model devices modified with sulfide maintained 88% of their initial performance for 1000 h under storage condition and 87% for 500 h under UV radiation. ZnS is demonstrated to act as both a cascade ETL and a passivating layer for enhancing the performance of PSCs.

A novel high-energy-density lithium-free anode dual-ion battery and in situ revealing the interface structure evolution.

Lithium-free anode dual-ion batteries have attracted extensive studies due to their simple configuration, reduced cost, high safety and enhanced energy density. For the first time, a novel Li-free DIB based on a carbon paper anode (Li-free CGDIB) is reported in this paper. Carbon paper anodes usually have limited application in DIBs due to their poor electrochemical performance. Herein, by using a lithium bis(fluorosulfonyl)imide (LiFSI)-containing electrolyte, the battery shows outstanding electrochemical performance with a capacity retention of 96% after 300 cycles at 2C with a stable 98% coulombic efficiency and 89% capacity retention after 500 cycles at 5C with a stable coulombic efficiency of 98.5%. Moreover, the electrochemical properties of the CGDIB were investigated with a variety of in situ characterization techniques, such as in situ EIS, XRD and online differential electrochemical mass spectrometry (OEMS). The multifunctional effect of the LiFSI additive on the electrochemical properties of the Li-free CGDIB was also systematically analyzed, including generating a LiF-rich interfacial film, prohibiting Li dendrite growth effectively and forming a defective structure of graphite layers. This design strategy and fundamental analysis show great potential and lay a theoretical foundation for facilitating the further development of DIBs with high energy density.

Novel MnO-Graphite Dual-Ion Battery and New Insights into Its Reaction Mechanism during Initial Cycle by Operando Techniques.

Dual-ion battery complements lithium-ion batteries in terms of the use of inexpensive materials and ease to construct cells. To improve the safety and energy density of dual-ion battery, in this paper, a novel MnO-graphite dual-ion battery is reported for the first time. Microporous MnO materials are used as anode, which exhibits a low conversion potential and a low voltage hysteresis. The MnO-graphite dual-ion battery can deliver a capacity of 104 mAh g-1 at 0.5C and exhibits good rate performances and cycling stability (capacity retention >93% after 300 cycles). A mechanism is proposed to explain the irreversibility in capacity during the initial cycle by using operando X-ray diffraction in combination with online electrochemical mass spectrometry and electrochemical impedance spectroscopy.

High-Energy Density Li metal Dual-Ion Battery with a Lithium Nitrate-Modified Carbonate-Based Electrolyte.

Lithium (Li) metal is a favorable anode for most energy storage equipment, thanks to its higher theoretical specific capacity. However, nonuniform Li nucleation/growth results in large-sized and irregular dendrites generated from the Li anode, which causes rapid capacity fade and serious safety hazard, hindering its widespread practical applications. In this paper, with the aid of a lithium nitrate (LiNO3) additive in a carbonate-based electrolyte, the Li anode shows low hysteresis for in excess of 1000 h at a current density of 0.5 mA cm-2. At the same time, a Li-graphite dual-ion battery exhibits an outstanding cycling stability at 5C; after 1000 cycles, 81% of the capacity is retained. After calculation, the Li-graphite dual-ion battery shows a competitive specific energy density of 243 Wh kg-1 at a power density of 234 W kg-1. Moreover, the linear sweep voltammetry test was first performed to analyze the Li nucleation/growth mechanism and explain the effect of the LiNO3 additive. The superior electrochemical properties of the Li-graphite dual-ion battery are ascribed to the formation of smooth Li composed of Li nanoparticles and a steady solid electrolyte interface film.

Study on a series of novel self-assembly supramolecular solar cells based on a double-layer structured chromophore of Zn-porphyrins.

We prepared in this work an anchoring porphyrin and a series of hat-porphyrins. The zinc atom of the hat-porphyrins can be coordinated axially with the pyridine moiety of the anchoring porphyrin which is anchored on the titania surface by a carboxyl group. The structures of the assemblies were confirmed using computational calculations, transmission electron microscopy (TEM) and energy dispersive spectrometry (EDS). Solar cell devices of the monomer anchoring porphyrin and its assemblies were fabricated and the photovoltaic performances were measured under standard AM 1.5 sunlight irradiance. We found that the assembly devices showed higher JSC and lower VOC than that of the monomer anchoring porphyrin device. However, the comprehensive influence of JSC and VOC led to an enhancement in the solar-to-electric power-conversion efficiency (PCE) of the assemblies. We also studied the variation of JSC and VOC using electronic absorption and emission spectroscopy, charge extraction measurements, transient photovoltage decay measurements and electrochemical impedance spectroscopy.