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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.

One great challenge for perovskite solar cells (PSCs) lies in their poor operational stability under harsh stimuli by humidity, heat, light, etc. Herein, a thermal-triggered self-healing polyurethane (PU) is tailored to simultaneously improve the efficiency and stability of inorganic CsPbIBr

Transition metal carbides or nitrides, collectively known as MXenes, are burgeoning two-dimensional materials for energy conversion and storage. The surface chemistry of MXenes could be specially tuned by the modified surface terminations, which directly influences their physicochemical properties. However, the in-depth study and understanding of the specific microstructure and the influence on the electrochemical performance of these terminations remain lacking. Herein, we present an accordion layered Ti2NT x MXene with –Cl and –O terminations obtained from copper chloride molten salt etching at a relatively low temperature. X-ray absorption fine structure and x-ray photoelectron spectroscopy analyses reveal the formation of Ti–Cl and Ti–O bonds on the surface of Ti2NT x MXene. Density functional theory calculations further suggest that the surface terminations tend to be replaced by –O terminations after Ti–Cl decoration, which implies promising lithium-ion storage performance due to the high lithium affinity of –O terminations. As a result, the Ti2NT x MXene based electrode delivers a high reversible capacity (303.4 mAh g−1 at 100 mA g−1), stable cycling capability (1200 cycles without capacity attenuation), and fast Li+ storage (52% capacity retention at 32 C). This work provides a new vision for MXene surface chemistry and an effective avenue to prepare high-performance nitride electrodes, expanding the diversity and controllability of the MXenes family.

The all-inorganic CsPbBr3 perovskite solar cell (PSC) is a promising solution to balance the high efficiency and poor stability of state-of-the-art organic-inorganic PSCs. Setting inorganic hole-transporting layers at the perovskite/electrode interface decreases charge carrier recombination without sacrificing superiority in air. Now, M-substituted, p-type inorganic Cu(Cr,M)O2 (M=Ba2+ , Ca2+ , or Ni2+ ) nanocrystals with enhanced hole-transporting characteristics by increasing interstitial oxygen effectively extract holes from perovskite. The all-inorganic CsPbBr3 PSC with a device structure of FTO/c-TiO2 /m-TiO2 /CsPbBr3 /Cu(Cr,M)O2 /carbon achieves an efficiency up to 10.18 % and it increases to 10.79 % by doping Sm3+ ions into perovskite halide, which is much higher than 7.39 % for the hole-free device. The unencapsulated Cu(Cr,Ba)O2 -based PSC presents a remarkable stability in air in either 80 % humidity over 60 days or 80 °C conditions over 40 days or light illumination for 7 days.

Dye-sensitized solar cells are promising solutions to energy and environmental problems. By addressing the high cost of preferred platinum counter electrode, Co/Se and Ni/Se nanocomposite counter electrodes are prepared by magnetron sputtering targets onto fluorine-doped tin oxide glass for dye-sensitized solar cell applications. The binary nanocomposite counter electrodes exhibit superior electrocatalytic activity toward I3− reduction compared to pure Ni, Se and Co electrodes. In particular, the dye-sensitized solar cell based on Co/Se counter electrode achieves a power conversion efficiency of 6.43%, which is much higher than 0.87%, 2.91%, 3.77% and 5.23% for Ni, Se, Co and Ni/Se solar cells, respectively. The preliminary results demonstrate it is a promising strategy to prepare robust counter electrodes by magnetron sputtering technique for dye-sensitized solar cells.

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.

The blossoming of portable electronics has raised the need to develop high power devices with multifunctionality, such as transparency and flexibility. Herein, for the first time a flexible and transparent crosslinked polyethyleneimine/poly(vinyl alcohol) composite is developed for the fabrication of mechanical energy harvester. The output of the device is markedly enhanced by the introduction of Au nanoparticles (NPs) due to the increase of the composite's dielectric property. With optimal load of AuNPs, the composite based device generates highest surface charge density manifested by maximum surface potential difference. Accordingly, an open-circuit voltage of 161.1 V, a short-circuit current density of 20 mA m−2, and a record-high peak power density of 17.73 W m−2 (16 mW) is achieved. Meanwhile, the device exhibits stability with no significant change in output after five months. Additionally, the charge transfer mechanism involved in the contact electrification process of the investigated composite is discussed. This study successfully demonstrates a promising potential of the composite in mechanical energy harvesting and an effective pathway to boost the output power through the engineering of the bulk dielectric properties.

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.

High-purity cesium lead bromide (CsPbBr 3 ) perovskite films are expected to promote the commercial manufacture of inorganic perovskite solar cells (PSCs). We present here a spray-assisted deposition of high-quality CsPbBr 3 films in ambient air by spin-coating a PbBr 2 layer and sequentially spraying CsBr multilayer to simplify the film fabrication technology. Upon optimizing spray deposition at four cycles, a high-purity CsPbBr3 phase is prepared and a maximized power conversion efficiency of 5.68% is achieved for the carbon-based inorganic PSC device. Furthermore, molybdenum disulfide quantum dots with an intermediate energy level are set at CsPbBr 3 /carbon interface to markedly increase charge extraction and to suppress electron-hole recombination, arising from the perovskite grain boundary passivation . Finally, the optimal inorganic PSC yields a stabilized efficiency of 6.80% under one sun illumination. Using this spray-assisted deposition method, this CsPbBr 3 solar cell with an active area of 1 cm2 achieves an efficiency of 4.12%. The photovoltaic performances are relatively stable even upon 80% relative humidity over 700 h without encapsulation.

All-inorganic CsPbBr

The precise regulation of interfacial charge distribution highly determines the power conversion efficiency of perovskite solar cells (PSCs). Herein, inorganic (NiCo)

Healing charge-selective contact interfaces in perovskite solar cells (PSCs) highly determines the power conversion efficiency (PCE) and stability. However, the state-of-the-art strategies are often static by one-off formation of a functional interlayer, which delivers fixed interfacial properties during the subsequent operation. As a result, defects formed in-service will gradually deteriorate the photovoltaic performances. Herein, a dynamic healing interface (DHI) is presented by incorporating a low-melting-point small molecule onto perovskite film surface for highly efficient and stable PSCs. Arising from the reduced non-radiative recombination, the DHI boosts the PCE to 12.05% for an all-inorganic CsPbIBr

Perovskite lattice distortion induced by residual tensile strain from the thermal expansion mismatch between the electron-transporting layer (ETL) and perovskite film causes a sluggish charge extraction and transfer dynamics in all-inorganic CsPbBr

Improved charge extraction and wide spectral absorption promote power conversion efficiency of perovskite solar cells (PSCs). The state-of-the-art carbon-based CsPbBr

With the advanced technologies such as 5 G network and internet of things (IoT), there are incredibly increasing sensors and corresponding applications emerging to benefit our daily lives. However, the power supplies for countless sensors become a serious issue to suppress further expansion of IoT. In this work, a self-powered triboelectric sensor (CN-STS) made of electrospun composite nanofibers is developed towards smart traffic monitoring and management. To meet the requirements of fast-response and high sensitivity for the smart traffic management, transferred charge density is adopted as sensing signals compared to voltage / current outputs for it can perfectly record the subtle differences and suitable for dynamic traffic monitoring. Carbon nanotube is further doped into PVDF nanofibers to improve the electrical output performance and pressure sensitivity. A relatively high sensitivity of 0.0406 μ Cm-2kPa-1 at low pressure range (0 to 75 kPa) and a sensitivity of 0.0032 μ Cm-2kPa-1 at higher pressure range (75 to 425 kPa) can be achieved by the CN-STS, indicating that the CN-STS is more sensitive at low pressure range. Moreover, by connecting to cloud IoT services, the functions of traffic flow management, overlapping and speeding vehicle capturing, and plate number recognition are realized by the CN-STS arrays with a compensation circuit. A charge amplifier is utilized in power management to process the charge input signals for better distinguishing the signals from none-vehicles and stabilize the volage output for further reading by the A/D convertor build in Raspberry Pi. The engineered self-powered triboelectric sensors not only open a new potential area for triboelectric nanogenerators but also significantly popularize the IoT industry.

Developing efficient and cost-effective counter electrodes (CEs) to catalyze triiodide reduction reaction is a persistent objective for high-performance dye-sensitized solar cells (DSSCs). One promising solution is to design electron-enriched electrode materials by combining conductive polymers with alloys. In this work, ternary hybrid PtM@polyaniline (M = Ni, FeNi) CEs are synthesized by one-step replacement reaction and in-situ polymerization reaction. When assembling into liquid-junction DSSCs, the power conversion efficiencies of 8.52% and 8.39% for the devices tailored with PtNi@polyaniline and PtFeNi@polyaniline CEs can be obtained. The experimental results demonstrate that the enhanced photovoltaic performances are mainly attributed to matching work function and high electrocatalytic activity of these well-designed hybrid CEs. Arising from the competitive reactions between transition metal and I2/I3− species, the dissolution reaction of Pt in liquid electrolyte is restricted and therefore the long-term stability of corresponding devices are significantly enhanced.

The impact of design and external parameters on the intrinsic output properties and load characteristics of hybrid energy harvesting generator is significant in both designing the generator and power management circuit and achieving high energy conversion efficiency. In this work, the intrinsic output characteristics of a hybrid triboelectric and piezoelectric generator is investigated, where the impacts of design parameters on the output properties and load characteristics under resistive and capacitive load conditions are demonstrated using a wide-ranging setting of the design parameters and compared with the theoretical calculations using a parallel hybrid model. The regularities concluded from the experimental results reflect the actual output behavior of a typical hybrid generator and provide evidence that the parameters have significant impacts on the intrinsic output properties, resistive load behavior and charging behavior. The outcomes of this study can be used as guidance toward designing effective structures and power management as well as in future simulation of a wide range of hybrid generators.

A new high-connected twin Keggin polyoxometalates (POM) based metal organic complex (POM@MOC), [Ag28(trz)18][HPWV3WVI9O40]2·2H2O (Ag28P2W24) (trz = 1,2,3-triazole), has been synthesized and structurally characterized. Single crystal X-ray analysis reveals that the new compound contains two unprecedented [10,10] connected Keggin POMs, which represents the highest connection number of POMs to any mixed-connected POM@MOCs to date. Another fascinating structural feature is that the twin Keggin POMs respectively dominates and fabricates two kinds of helices in the POM@MOCs. In addition, to improve the photocatalytic activity of the new compound Ag28P2W24, its polypyrrole (PPy) composite (PPy/Ag28P2W24) has been prepared and exhibits good uptake capacities and photocatalytic degradation for Rhodamine B dye under the visible light.

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.

The crystal distortion such as lattice strain and defect located at the surfaces and grain boundaries induced by soft perovskite lattice highly determines the charge extraction‐transfer dynamics and recombination to cause an inferior efficiency of perovskite solar cells (PSCs). Herein, the authors propose a strategy to significantly reduce the superficial lattice tensile strain by means of incorporating an inorganic 2D Cl‐terminated Ti3C2 (Ti3C2Clx) MXene into the bulk and surface of CsPbBr3 film. Arising from the strong interaction between Cl atoms in Ti3C2Clx and the under‐coordinated Pb2+ in CsPbBr3 lattice, the expanded perovskite lattice is compressed and confined to act as a lattice “tape”, in which the PbCl bond plays a role of “glue” and the 2D Ti3C2 immobilizes the lattice. Finally, the defective surface is healed and a champion efficiency as high as 11.08% with an ultrahigh open‐circuit voltage up to 1.702 V is achieved on the best all‐inorganic CsPbBr3 PSC, which is so far the highest efficiency record for this kind of PSCs. Furthermore, the unencapsulated device demonstrates nearly unchanged performance under 80% relative humidity over 100 days and 85 °C over 30 days.

By adjusting pH value, two new Keggin polyoxometalate-based hybrid compounds with different helical structure, [Ag6(btp)(pyttz)6·(HSiMo12O40)2]·4H2O (1) and [Ag2(pyttz)4·(H2SiMo12O40)2]·(TMA)2·4H2O (2), (pyttz = 3-(pyrid-4-yl)-5-(1 H-1,2,4–3-yl)-1,2,4-triazolyl, btp = 5,5′-di(pyridin-4-yl)-1 H,1′H-3,3′-bi(1,2,4-triazole), TMA = tetramethylammonium), were successfully isolated by hydrothermal reaction and structurally characterized. Structural analysis shows the nature of the inorganic meso-helical channel in compound 1 and 2D homological helical layer in compound 2. It is also interesting that a new organic ligand btp is formed in situ by the coupling of N-Heterocycle in 1. In addition, the catalytic activities of 1 and 2 as solid-acid catalyst are explored, and the results indicate that 1 and 2 are a kind of highly-efficient and promising solid catalysts. Additionally, the proposed generation mechanism of btp in situ is also discussed.

An assembly of cyclodextrin metal-organic frameworks (CD-MOFs) has aroused extensive research interests due to their excellent encapsulation capacity and biocompatibility. In this work, starting from the chiral building block α-cyclodextrin (α-CD), a novel α-CD-MOF compound with left-handed chiral helices, [Na(H2O)(C36H60O30)]·H2O (Na-α-CD-MOF), was synthesized through changing the diffusion solvent, and then structurally characterized. Single crystal X-ray diffraction analysis reveals that Na-α-CD-MOF exhibits a 3D left-handed helical chiral framework with large cavities (740 A3). The result of a drug adsorption assay shows Na-α-CD-MOF possesses a more efficient drug adsorption capacity than α-CD matrix, and the solubility of the drug adsorbed in Na-α-CD-MOF can be greatly enhanced. All the results, including the lower cytotoxicity, indicate that Na-α-CD-MOF is an excellent kind of renewable, environmental friendly and biocompatibility drug carrier material.

A new Keggin polyoxometalate based inorganic-organic hybrid compound, [Ag5(trz)4·(H2O)2][H2PW12O40] (1), was successfully synthesized and characterized. Single crystal X-ray analysis reveals that the title compound possesses fourfold meso-helical structure fabricated by POM-Ag inorganic chains, then the 1D metal-organic chains insert into the 3D POM-Ag framework using Ag as their common junction obtaining the whole structure with {4}8{48 · 896 · 1216} topolopy. The title compound represents the most complex helical conformation (fourfold meso-helix) among the Keggin based hybrids' materials to date, and [PW12O40]3 − polyanions in the title compound also exhibit the highest coordination number so far, which dominates the formation of fourfold meso-helix.

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.

The all-inorganic CsPbBr

A new fluconazole-functionalized polyoxometalate-based metal-organic framework (POMOF) [Ag

The weather-dependence and intermittent photoelectric conversion capacity of the traditional photovoltaics call for rational design on device architecture to realize persistent power output under multiple-energy-source stimuli. Herein, we demonstrate a novel triboelectric nanogenerator/silicon (TENG/Si) tandem hybrid solar cell by stacking top silver/polydimethylsiloxane sub-cell onto bottom monocrystalline Si solar cell for simultaneously harvesting solar and rain energies. Upon systematically optimizing the device configuration and the properties of top nanogenerator, the bottom Si solar cell is used as a friction layer to regulate the charge distribution of TENG, achieving a short-circuit current of 7.59 μA, a peak open-circuit voltage of 37.19 V under the stimuli of single raindrop and a power conversion efficiency enhancement by 20% in comparison with pristine Si solar cell. Finally, 26 blue light-emitting diodes can be lighted up by one raindrop. Given the compelling advantages of enhanced power output and expanded working time, this physical proof-of-concept TENG/Si tandem hybrid solar cell provides new opportunities to collect multiple energies from nature and to promote the development of weather-independent solar cells.

In the last decade, organic–inorganic hybrid lead-halide perovskites have been attracted tremendous attentions in the photovoltaic and optoelectronic community. Especially for perovskite solar cells (PSCs), the certified efficiency is up to as high as 25.5%, which has surpassed polycrystalline silicon solar cells and is comparable to the monocrystalline silicon solar cells. Till now, although the chemical instability of perovskite has been well alleviated by optimizing the lattice structure, the detrimental lead element is still a challenge for the commercialization process of PSC devices. To effectively resolve this issue, lead-free halide perovskites (LFHPs) have gained growing attentions recently due to their theoretically excellent optoelectronic properties and eco-friendly feature. With the aim to promote the development of LFHPs, in this review, we have mainly summarized the recent advancement of various LFHP materials and their applications in photovoltaics, light-emitting diodes (LEDs), photodetectors and other devices. Strategies for stabilization of perovskite lattice and performance improvement of optoelectronic devices including fabrication technology, compositional engineering and interfacial optimization are also emphasized. Finally, the potential and challenges of LFHPs are further discussed, providing new research direction for future development.

A new Keggin arsenomolybdate based inorganic–organic hybrid compound containing complementary inorganic double helical chains, [Ag2(pyttz)3(H2O)][HAsMo12O40]·H2O (1), was successfully synthesized and characterized. Single crystal X-ray analysis reveals that compound 1 exhibits 3D supramolecular framework with (43)(44·62)(47·610·84) topology, in which the complementary double helical chains constructed by the left- and right-handed helical chains are found. In the crystal engineering point of view, the rich coordination atoms and conjugated heterocyclic rigid plane of pyttz organic ligand and the multiple twisted V-shaped coordination modes of Keggin POMs facilitate the formation of the inorganic helical structure. In addition, the title compound exhibits good photocatalytic degradation of methylene blue dye, and is very stable and easily separated from the catalytic system for reuse as well.

In this contribution, combined triboelectric and piezoelectric generators (TPEG) with a sandwich structure of aluminum-polydimethylsiloxane/polyvinylidene fluoride composite-carbon (Al-PPCF-Carbon) are fabricated for the purpose of mechanical energy harvesting. Improved by the surface modification of PPCF with zinc oxide (ZnO) nanorods through a hydrothermal method, the TPEG generates an open-circuit voltage (Voc) of ≈40 V, a short-circuit current (Isc) of 0.28 μA with maximum power density of ≈70 mWm−2, and maximum conversion efficiency of 34.56%. Subsequently, in order to understand the transduction mechanism of the triboelectric and piezoelectric effects, analyses focusing on the potential composition ratio in the final output and the impact of ZnO interfacial nanostructure are carried out. The observed potential ratio between triboelectric and piezoelectric effects is 12.75:1 and the highest potential improvement by ZnO nanorods of 21.8 V is achieved by the TPEG fabricated with spacer. Finally, the relationships between the voltage, power density, conversion efficiency, and the external load resistances are also discussed. Overall, the fabricated TPEG is proved to be a simple and effective nanogenerator in mechanical energy conversion with enhanced output potential and conversion efficiency.

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.

The in-depth understanding on the electrification behavior of dielectric materials is a prerequisite to improve their surface triboelectric charge density in triboelectric nanogenerators (TENGs). Herein, triboelectric charging affinities and polarities of all-inorganic cesium lead tri-bromine (CsPbBr3) and alkaline earth ions doped CsPb1-xMxBr3 (M = Mg2+, Ca2+, Sr2+, Ba2+, x = 0–1) perovskites are systematically investigated by assembling into vertical contact-separation TENGs. An enriched triboelectric series supplemented with pristine CsPbBr3 and CsPb1-xMxBr3 perovskites with quantified triboelectric charging polarity is presented through analyzing the electrical output performances, figure-of-merits (FOM), dielectric property, work function, bond energy and electron binding energy. Systematical analyses of three different configurations of dielectric/perovskite TENG, carbon/perovskite TENG and perovskite solar cell are compared in dark and under illumination. It is found that the photoinduced charges play significant role in enhancing the triboelectrification charges and altering charging polarity of perovskite. Our work supplements inorganic perovskites to triboelectric series and provides new insights on inorganic perovskite in the foundation of tribo-photovoltaic theory and triboelectric devices.

Triboelectric nanogenerator (TENG) is an advanced energy conversion device to harvest low-frequent mechanical energy from nature, and boosting triboelectric charge density and regulating charge storage behavior are promising solutions to improve their output performances. In this work, rhombus Co(OH)(CO3)0.5/Pt/CsPbIBr2 multilayer nanoarray is tailored as a friction layer coupled with poly(vinylidene fluoride) to increase the in-depth distribution of triboelectric charges and to block the combination with induced positive charges on the electrode, the champion perovskite TENG achieves a short-circuit current density of 3.1 μA cm−2, an open-circuit voltage of 243 V and a triboelectric charge density of 9.57 nC cm−2, which can instantaneously light up 61 commercial LEDs at per contact. Due to the reduced charge loss in metallic electrode and increased internal-space-charge zones of triboelectric charges in frictional layer assisted by the bottom Co(OH)(CO3)0.5 and intercalated Pt layers, the tri-layered Co(OH)(CO3)0.5/Pt/CsPbIBr2 raises the power density peak by a factor of 4.5, reaching 2.04 W m−2 at a contact frequency of 0.5 Hz. In addition, the perovskite TENGs demonstrate an excellent stability over 1350 cycles test in ambient atmosphere. This work may provide new insights on manufacturing semiconductor-featured TENG platforms.

Triboelectric nanogenerators (TENGs) have attracted considerable interests in flexible electronics as self-powered sources with adaptability, flexibility, and multifunctionalities. Endowing TENG with wearability is considered to be one of the most promising and practical strategies to cater the fourth industrial revolution with the features of intelligence, information, miniaturization, portability, and low power consumption. Herein, nanowrinkle-patterned flexible woven structured TENGs (FW-TENGs) are fabricated based on a polydimethylsiloxane/polyvinylidene fluoride (PDMS/PVDF) composite films. Through systematically investigating and optimizing the dielectric property of composite film, impacts of film thickness and surface architectures, an instantaneous maximum power density of 832.05 mW/m2 is registered by the champion FW-TENG, which is comparable to the state-of-the-art woven structured TENGs. Moreover, the device presents a highly stable Voc output after continuous operation over 2200 cycles, implying the outstanding ability of structural retention and fatigue resistance during wearing FW-TENG. Stimulating by knee bending, arm swing and elbow bending, the self-powered FW-TENG is successfully realized with multi-adaptability and compatibility with various fabric clothes, demonstrating the great application potential as wearable electronics for mechanical energy harvesting, pressure sensing and human-machine interfacing without external energy supply.

Regulating the dynamic behavior of triboelectric charges between dielectric layer and metallic electrode is a promising solution to suppress charge screen effect and to improve the output performances of triboelectric nanogenerators (TENGs). Herein, the cutting-edge inorganic CsPbBr3 perovskite is used as a dielectric material to tailor metal/perovskite Schottky junction for robust TENG applications. Arising from the induced electric field, the electron transfer from perovskite to metallic nanoparticle significantly promotes the charge accumulation at the bottom electrode, which in turn increases the overall power output of TENGs. After precisely regulating the barrier height of Schottky junction by means of optimizing noble metals (Ag, Au, and Pt) and fabricating the bulk Schottky junction, the electron drift-diffusion processes and the triboelectric charge storage behavior have been carefully optimized, achieving an enhanced power density of 3.31 W m−2 with an open-circuit voltage up to 240 V and a short-circuit current density of 4.13 μA cm−2. This work may give new insights into the dynamic behavior of triboelectric charges for advanced TENG platforms.

Triboelectric nanogenerators (TENGs) have attracted considerable interests because of their high conversion efficiency from low-frequent mechanical energy to electricity. Robust dielectric materials are critical in enhancing the contact electrification charge density of TENGs. Herein, all-inorganic cesium lead halide (CsPbX3, X = I, Br, Cl) perovskites with tunable morphologies and dielectric properties are synthesized through a facile solvent etching method and applied as the triboelectric materials in perovskite TENGs. The influences of effective contact area and the dielectric properties associated with electron donating capacity of perovskite films are systematically investigated through solvent and compositional engineering. Compared with the all-inorganic perovskite free of etching, the crystal growth conditions are well controlled. In addition, the doping of Cl− or I− ions is in favor of regulating the polarity and electronic structure of the [PbBr6]4- octahedral. Benefitting from the physical surface engineering approaches for enhancing the triboelectric charge density and the chemical doping for regulating dielectric property, an open-circuit voltage of 192 V, a short-circuit current of 16.7 μA and maximum power density of 1.2 W m−2 at a contact frequency of 0.5 Hz are achieved in the champion CsPbBr2.6I0.4 TENG. The discovery of extraordinary dielectric behavior of the perovskite halides may pave the way of perovskite TENGs with boosting triboelectric charge density for mechanical energy harvesting.