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A robust HOF has been employed as cathode for LIBs. The decoration of rich redox-active moieties in HOFs introduces the surface-controlled capacitive mechanism in LIBs, accessing a high capacity, high rate capability and excellent cycling stability.

A bipolar-type 2D COF has been fabricated through the condensation of TPPDA and Cu-TFPP. The COF cathode with p- and bipolar-type redox-active centers exhibits good performance for Li-ion batteries.

The rapid development of the Internet of Things has resulted in the harvesting of distributed sustainable energy receiving increasing attention. Recently, a study on triboelectric nanogenerators (TENGs) for collecting low-frequency and irregular-amplitude ocean wave energy has attracted significant interest. Herein, a self-powered seesaw-structured spherical triboelectric–electromagnetic hybrid nanogenerator (SSTE-HNG) combining various working modes is presented for harvesting wide-frequency wave energy from different directions and self-powered sea surface wireless positioning. The electrical output performances were systematically investigated and optimized via studying the effects of the configuration parameters, including the central slider mass, oscillation frequency, and swing amplitude of each module and the entire device; the instantaneous maximum output power densities of the origami zigzag-multilayer structured (OZ), freestanding layer rolling (FL), and electromagnetic generator (EMG) modules can reach 17, 4.8, and 9.8 W m−3, respectively, at an oscillation frequency of 0.7 Hz, and around 410 LEDs can be lit when operating the SSTE-HNG. Finally, the output voltage of the SSTE-HNG was stabilized using a transistor-controlled power management circuit for charging a 4.7 mF commercial capacitor in the range of 2.7 to 3.3 V; the seesaw-structured spherical buoy was used to drive a global positioning system (GPS) module for dynamic sea surface real-time wireless positioning, and our lab building on campus was successfully located upon installing the SSTE-HNG in a water tank. This study provides an ingenious design for achieving synchronized movements among hybrid effect/mode-based generators, and a self-powered buoy with a hybrid nanogenerator for sea surface wireless positioning was realized, which has the potential to be integrated with distributed electronics, such as sensors that collect sea surface meteorological information, in the future in the field of smart marine technology.

Simultaneously tailoring the interfacial energetics and healing the defective nanostructure of perovskite films is important for promoting the power conversion efficiency of perovskite solar cells (PSCs). Herein, a fluoroaniline molecule-terminated graphene oxide (GO) is fabricated as an interface modulator in all-inorganic CsPbIBr2 PSCs. Owing to the amidation reaction induced p–π conjugation effect with an adjacent benzene ring, the spontaneous electron transfer from oxygen-containing groups at the GO surface to the aniline unit causes the self-reduction and p-type doping of GO, benefiting hole extraction and delocalization. Together with the passivation effect by –F termination with under-coordinated Pb2+, the best device delivers an efficiency of 11.08% with superior stability originating from the presence of hydrophobic C–F bonds, the reduced defects and suppressed ion migration. Moreover, the functionalized GO can effectively capture and obstruct the leakage of Pb2+ ions from a destructive device, demonstrating its unique advantages in high-performance PSC platforms.

A new polyoxometalate (POM) pillared metal–organic framework (POMOF), [Cu24(Trz)16(H2O)Cl4(HPMo12O40)] (Cu-POM, Trz = 1,2,3-triazole), was synthesized and characterized. Crystal analysis reveals that the Keggin POMs are inserted into copper–triazole layers with a graphite-like structure generating a POM-supported porous three-dimensional framework. Owing to the combination of the multi-electron redox property of POM units and the open porous framework, Cu-POM can be utilized as an anode material for lithium ion batteries (LIBs), and exhibits a reversible capacity of 525 mA h g−1 at a current density of 100 mA g−1 after 100 cycles. Moreover, to illustrate lithium storage, the impedance spectra of compound Cu-POM during the first and 100th charge process have also been studied. The study of Cu-POM in this work might guide the development of POM-based electrode materials for LIBs.

The electron-transporting layer (ETL) plays a non-negligible role in determining the charge extraction and transfer behaviors from perovskite films under solar irradiation for high efficiency perovskite solar cells. A suitable band structure, good conductivity, high electron mobility and low trap state density are preferred for the desired ETL to maximize the electricity generation and minimize the charge recombination. Herein, we have demonstrated that the incorporation of antimony (Sb) dopants into the lattice of low-temperature processed TiO2 nanocrystals can effectively suppress the formation of under-coordinated Ti3+ and oxygen vacancies, leading to improved electronic conductivity and mobility. When assembling into all-inorganic, carbon-based CsPbBr3 planar perovskite solar cells free of noble metal electrodes, an enhanced efficiency of 8.91% with an ultra-high open-circuit voltage of 1.654 V and reduced hysteresis from 32% to 15% is achieved based on the Sb-doped TiO2 ETL. The mechanism behind this phenomenon is mainly attributed to the improved perovskite film quality and significantly reduced charge recombination. Taking the advantages of low temperature, low defect state density, high electrical conductivity and mobility into consideration, the Sb-doped TiO2 ETL demonstrates great potential in advanced perovskite solar cells even in flexible devices.

Triboelectric nanogenerators (TENGs) are preferred energy conversion devices to scavenge low-frequency mechanical energy sources from ambient environments due to their easy-to-operate principle structures, cost-effectiveness, and wide application areas. Halide perovskites have been demonstrated to be a good candidate as triboelectrification dielectric materials in TENGs, yet their triboelectrification behavior and charging affinity are still unclear. Herein, inorganic CsPbBr3 perovskites doped with halide ions (I− and Cl−) are systematically investigated focusing on their triboelectric behaviors through fabricating perovskite TENGs in vertical contact-separation mode. The charging polarities of different halide perovskites are qualified and ascertained by evaluating their triboelectric output signals, power density, charging capacity, and figure of merit (FOM), which are confirmed by the deviation of electron binding energy, carrier mobility, surface potential and dielectric properties affected by different halide ion incorporation. Meanwhile, the champion perovskite TENG demonstrates an excellent operational durability in an ambient atmosphere. A modified triboelectric series containing inorganic perovskites with various halide ions is established based on the empirical results. This work not only enriches the triboelectric series, but also expands the application of perovskite materials in mechanical energy harvesting fields.

Triboelectric nanogenerators (TENGs) have attracted growing attention because they are advanced energy conversion devices to efficiently harvest low-frequency mechanical energy from nature. How to increase the permittivity of electrode materials as well as the surface charge density is technically important to improve the output performances of a robust TENG. In this study, an all-inorganic cesium lead bromide (CsPbBr3) perovskite film with semiconducting characteristics is combined with metallic nano-platinum to build bulk Pt/CsPbBr3 Schottky junctions, which are used as triboelectric electrode materials in vertical contact-separation perovskite TENGs. The systematic characterization demonstrates that the electron binding energy and dielectric properties of bulk Pt/CsPbBr3 Schottky junction tailored perovskite films are maximized by optimizing the Pt dosage. An open-circuit voltage of 273 V, a short-circuit current density of 30.3 μA cm−2 and an instantaneous maximum power density of 1295.5 mW m−2 are achieved by the champion Pt/CsPbBr3 TENG at a Pt dosage of 0.5%. A maximum energy storage of 3.96 mJ is stored in a 1 μF capacitor within a 300 s charging period. This work provides new insights into Schottky junction TENGs for enriching the fundamental principles of both halide perovskites and TENGs.

Triboelectric nanogenerators (TENGs) have received growing attention to efficiently harvest waste micromechanical energy from ambient atmosphere such as hydrodynamic energy from raindrops. The comprehensive understanding of the electrification mechanism and dynamic charging behavior between rain droplets and the collecting substrate is essential for multi-application scenarios of TENGs. Herein, a bi-electrode freestanding mode TENG (BF-TENG) is designed to harvest hydrodynamic energy from rain droplets with regard to the implementation at rooftops, terraces and greenhouse roofs. By placing the BF-TENG horizontally, an intriguing cumulative charging behavior of successive water droplets is in-depth investigated, which expands the fundamental charging mechanism for maximizing the surface charge storage capacity. Optimal configurations of the inclination angle and drop height of the BF-TENG system are further studied for improving the electrification charge density as well as power output and extending the application area to inclined surfaces such as rooftops and umbrellas. Through coupling of the cumulative charging behavior and the optimal configurations of BF-TENG, an instantaneous maximum power density of 1.838 W m−2 is achieved and 30 LEDs can be lit up when spraying tap water from a shower faucet on a BF-TENG installed on an umbrella, demonstrating the promising application of BF-TENGs for hydrodynamic energy harvesting and providing multi-implementation scenarios of BF-TENGs with the potential to be installed on the roof top, terrace, umbrella and car hood, which can be utilized as the warning light at rainy night for safe guarding.

Inorganic perovskites are regarded as “star” semiconductors with unique ferroelectricity due to their superior triboelectric behaviors to those of state-of-the-art dielectric polymers when applied in a triboelectric nanogenerator (TENG). An in-depth understanding on the charging mechanism of these inorganic halide perovskites may help design a robust TENG platform. Herein, alkali metal ion doped cesium lead tri-bromine Cs1−xAxPbBr3 (A = Li+, Na+, K+, and Ru+, x = 0–1) perovskites are systematically investigated concentrating on their triboelectric behaviors for the first time. The triboelectric charging affinities of these perovskites are ascertained by evaluating the electrical output performances and figures of merit of TENGs based on perovskite/poly(vinylidene fluoride) pairs in vertical contact-separation mode. Finally, a supplemented qualitative triboelectric series including Cs1−xAxPbBr3 perovskites is established regardless of the doping concentration, and can be utilized as a benchmark to guide the future dielectric selection for robust TENGs. This study not only casts light on the determination of an expanded triboelectric series, but also provides new insights into inorganic perovskites in the application of mechanical energy harvesting.

The band-energy structure, electron mobility and electronic trap states of the electron-transporting layer (ETL) are critical for perovskite solar cells (PSCs). However, the state-of-the-art titanium oxide (TiO2) ETL prepared by means of high-temperature processing technology requires a long preparation time and a lot of energy consumption; and the low-temperature processed species always present unfavourable electrical properties. In this work, we demonstrate that photoactivated transition metal dichalcogenide quantum dots (TMDC QDs, MoS2 and MoSe2) boosted a low-temperature processed TiO2 (L-TiO2) ETL for all-inorganic CsPbBr3 PSCs without a hole-transporting layer or precious metal electrode. Arising from the photogenerated electron injection from TMDC QDs to L-TiO2 under light irradiation, the electronic trap states and the electron mobility of ETL were effectively regulated, which in turn significantly enhanced the electron extraction from perovskite to the L-TiO2 ETL and reduced the carrier recombination. Finally, the optimal CsPbBr3 PSC achieves an enhanced power conversion efficiency of 10.02% with an ultrahigh open-circuit voltage of 1.615 V and excellent long-term stability, providing a new path to efficient photovoltaic devices.

Substitution of Pb2+ sites with smaller isovalent ions has been regarded as an effective strategy to optimize the crystal lattice of organic–inorganic hybrid perovskites such as releasing lattice strain, increasing the formation energy of vacancies and tuning the bandgap energy distribution. We report here the compositional engineering of the inorganic CsPbBr3 perovskite by doping divalent hard Lewis acids (Mg2+, Ca2+, Sr2+ and Ba2+) and their application in all-inorganic perovskite solar cells free of hole transporting layers and precious metal electrodes. By optimizing the doping dosage, a maximal power conversion efficiency as high as 9.63% is achieved for a CsPb0.97Sr0.03Br3 based photovoltaic device, mainly attributed to the enlarged grain sizes and suppressed formation of point defect (vacancies) within perovskite films, therefore reducing the photocurrent loss within modules. Furthermore, the unencapsulated Sr-containing solar cell shows ultrastability comparable to that of state-of-the-art CsPbBr3 perovskite solar cells under persistent attack in 80% relative humidity over 800 h. The increased efficiency and improved stability demonstrate all-inorganic perovskite solar cells with divalent hard Lewis acid doped CsPbBr3 perovskites to be a new frontier for thin-film photovoltaics.

Film-type electrokinetic generators are a cost-effective and robust strategy for harvesting multi-frequent ocean wave energy. However, the intrinsic property of a low charge density prevents the generator from further improving the energy conversion efficiency. Herein, we present a photo-induced charge-boosting liquid–solid electrokinetic generator (L-SEKG) with a structure of polyurethane/graphene oxide-carbon black-multi-walled carbon nanotube/carbon quantum dots/copper (PU/GO-CB-MWCNT/CQDs/Cu) to harvest ocean wave energy. Systematic studies on the relationship between the output performance and GO dosage, MWCNT dosage, wave frequency, seawater temperature, CQD dosage and illumination intensity respectively were performed to optimize the energy conversion efficiency. Under standard sun illumination (100 mW cm−2, air mass 1.5), a maximum voltage of 0.1 V, a current of 0.39 mA and a power density of 26.6 mW m−2 were achieved by the L-SEKG with a GO/CB ratio of 4 : 3, a MWCNT dosage of 17%, a wave frequency of 0.9 Hz and at a temperature of 25 °C. Further, a stability test of L-SEKG was conducted under continuous waving using real seawater, and a circuit design for scaling up the power output is presented as well. The results demonstrate that the photo-induced L-SEKG has promising applications in large-scale networks to scavenge water wave energy efficiently.

Perovskite solar cells (PSCs) have attracted tremendous interest because of their rapid improvement in power conversion efficiency (PCE) from the initial PCE of 3.8% for the first prototype to the certified PCE of 25.2% in 2019. However, the inherent chemical instability of organic–inorganic hybrid perovskite halides influenced by moisture, heat and ultraviolet light is still a critical issue for them to meet application-specific requirements owing to the weak-bonded organic components in the hybrid crystal structure. The use of all-inorganic perovskites CsPbI3−xBrx (x = 0, 1, 2, and 3) as light-harvesters by completely substituting organic species with inorganic Cs+ ions has been recently regarded as a promising solar conversion technology. Since the initial efficiency of 2.9% achieved in 2015, the highest PCE record for inorganic PSCs has risen to 18.4% through structure optimization, compositional engineering, interfacial engineering, solvent control and surface passivation, etc. This article is dedicated to providing an up-to-date review on the development of inorganic PSCs tailored by various inorganic perovskite materials with gradually changed optical properties and stability, as well as the film-making methods and interfacial engineering technologies. Their limited efficiencies in theory and recombination mechanisms are also predicted with a detailed balance model. Finally, we focused on the state-of-the-art strategies for enhancing the photovoltaic performance and identified new challenges and outlooks for future studies in this field.

Perovskite-structured cesium lead bromide (CsPbBr3) halide provides new opportunities for promoting the commercialization of perovskite solar cells (PSC) due to its high carrier mobility and light absorption coefficient as well as remarkable environmental stability at high humidity and high temperatures. Herein, all-carbon electrodes from multi-walled carbon nanotubes (MWCNT) and carbon black (CB) were prepared for all-inorganic CsPbBr3 PSCs with the configuration of FTO/c-TiO2/m-TiO2/CsPbBr3/carbon. The as-prepared electrodes were free of hole-transporting layers and precious metals. The work function and electrical conductivity of the carbon electrode were tuned by changing the MWCNT/CB ratio to reduce charge recombination at the perovskite/carbon interface. The optimal all-inorganic PSC achieves a maximum power conversion efficiency of 7.62% using the MWCNT (75 wt%)/CB (25 wt%) electrode in comparison with 6.24% for the pure MWCNT-based device. Upon persistent attack by 80% RH in air atmosphere, the solar cell retains 95% of its initial efficiency over 1100 h.

Fabrication of a flexible, lightweight and cost-effective mechanical energy harvester is a promising approach for next-generation wearable electronics. Herein, a triboelectric mechanical energy harvester based on cashmere fibers is developed for the first time using a facile fabrication process with polytetrafluoroethylene as the triboelectric counterpart. The surface properties of cashmere play a significant role in output performance. Remarkable power output can be achieved when subjected to Tween 20 treatment with an open-circuit voltage of 19.5 V, which is 4.5-fold higher than that of a pristine fiber based harvester. As a H-bond donor, the lowered ionization potential of cashmere significantly increases its tendency to lose electrons during contact electrification. The treated cashmere based harvester can achieve an output power density of 41.7 mW m−2 at a load resistance of 14.1 MΩ. Additionally, the device displays good stability over a wide range of relative humidity. This study demonstrates a new approach for surface modification via mild solvent treatment. Successful demonstration of a cashmere based harvester as a power source for light-emitting diodes shows potential application in self-powered wearable electronics.

All-inorganic perovskite solar cells (PSCs) are regarded as a promising solution to improve the environmental tolerance of emerging photovoltaics; however, the narrow light response (

Cost-effective and stable CsPbBr3-based inorganic perovskite solar cells (PSCs) are regarded as promising candidates for next-generation photovoltaics. However, the large interfacial energy differences at the CsPbBr3/hole-transporting layer lead to serious charge recombination and poor charge extraction kinetics. Herein, we prepare a series of hole-transporting materials (HTMs) to improve hole extraction and to reduce electron–hole recombination at the CsPbBr3/HTM interface. In comparison with the power conversion efficiency (PCE) of 6.10% for an HTM-free device, the CsPbBr3 PSCs with polymeric HTMs such as polythiophene, polypyrrole and polyaniline yield efficiencies of 8.36%, 8.32% and 7.69%, respectively. Similarly, the inorganic PSC with organic small molecule BT-BTH achieves a PCE as high as 9.32% due to the improved hole conductivity. Moreover, the unencapsulated PSC with BT-BTH maintains 94% of its initial efficiency in 70% relative humidity over 80 days.

Energy scavenging techniques based on piezoelectric and triboelectric effects have become increasingly attractive in the last few years, due to their efficient working processes as well as promising output potentials. Here, we report the fabrication of hybrid generators based on PDMS composite films embedded with a range of functional materials combining both piezoelectric and triboelectric properties. Single effect generators were also fabricated in order to analyze the output contribution of each effect in contrast to the combined effect, and to understand the impact of each material on the piezoelectricity or triboelectricity during the power generation process. An average open-circuit voltage of 48.46 V with an energy conversion efficiency of 31.62% was achieved by a device based on the PDMS composite with PVDF/MWCNT/BaTiO3. The ratio of the triboelectric and piezoelectric effects in the composite generators is introduced and analyzed in this work. Our findings not only indicate that individual materials in a composite can synergistically enhance their intrinsic properties, but also validate that the capacity of composites in converting mechanical energy is far beyond that of the individual material.

Two new polyoxometalate-templated organic–inorganic hybrid compounds with different metal–organic frameworks, [Ag5(trz)6][H4PMo12O40] (1) and [Ag10(trz)8][HPMo12O40] (2) (trz = 1,2,4-triazole), have been prepared based on the same organic ligands under different pH values. Compound 1 exhibits a honeycomb 2D [Ag5(trz)6] network and 3D graphite-like hybrid framework, and compound 2 exhibits a 3D {Ag3[Ag6(trz)6][Ag(trz)2]} framework with 2D channels, in which [PMo12O40]3− polyanions locate in the center of channels. To the best of our knowledge, [PMo12O40]3− polyanions represent the highest coordination number in 1 and terminal oxygen coordination number in 2 of Keggin POMs up to date. A comparison of two compounds demonstrates that the coordination mode of 1,2,4-triazole ligands and Keggin POMs templates have important influences on the assembly of different frameworks. In addition, compounds 1 and 2 exhibit good photocatalytic degradation of Rhodamine-B, and are very stable and easily recyclable as well.