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Although the efficiency of perovskite solar cells is over 25%, there is still a big difference between the open-circuit voltage and its theoretical value, which is ascribed to defects in the perovskite films.

The advanced lithium storage performance of the P-doped self-assembled V2C MXene/NiCo-LDH hybrid benefits from high capacitive contribution, high electrical conductivity, and good structural stability.

Power consumption makes next-generation large-scale photodetection challenging. In this work, the source-gated transistor (SGT) is adopted first as a photodetector, demonstrating the expected low power consumption and high photodetection performance. The SGT is constructed by the functional sulfur-rich shelled GeS nanowire (NW) and low-function metal, displaying a low saturated voltage of 0.61 V ± 0.29 V and an extremely low power consumption of 7.06 pW. When the as-constructed NW SGT is used as a photodetector, the maximum value of the power consumption is as low as 11.96 nW, which is far below that of the reported phototransistors working in the saturated region. Furthermore, benefiting from the adopted SGT device, the photodetector shows a high photovoltage of 6.6 × 10

Substitution of lead (Pb) with tin (Sn) is a very important way to reduce the bandgap of metal halide perovskite for applications in solar cells, and near infrared (NIR) light-emitting diodes (LEDs), etc. However, mixed Pb/Sn perovskite becomes very disordered with high trap density when the Sn molar ratio is less than 20%. This limits the applications of mixed Pb/Sn perovskites in optoelectronic devices such as wavelength tunable NIR perovskite LEDs (PeLEDs). In this work, we demonstrate that alkali cations doping can release the microstrain and passivate the traps in mixed Pb/Sn perovskites with Sn molar ratios of less than 20%, leading to higher carrier lifetime and photoluminescence quantum yield (PLQY). The external quantum efficiency (EQE) of Sn0.2Pb0.8-based NIR PeLEDs is dramatically enhanced from 0.1% to a record value of 9.6% (emission wavelength: 868 nm). This work provides a way of making high quality mixed Pb/Sn optoelectronic devices with small Sn molar ratios.

The high lithium storage performance of 3D flower-like MoO2/Ni/C through a temperature annealing strategy is benefitted from the high capacitive contribution, high electrical conductivity, and good structural stability.

As devices with plasticity similar to biological synapses, photovoltaic memristors based on the bulk photovoltaic effect exhibit impressive abilities for autonomous learning and memory.

In this paper, inorganic halide perovskite cesium lead bromide (CsPbBr3) films are epitaxially grown on (100)-oriented SrTiO3 substrates by pulsed laser deposition (PLD). This method has the distin...

Using large-scale industrial production, such as roll-to-roll (R2R) solution printing technology, to achieve lab-to-manufacturing translation should be an inevitable process for the commercializati...

Traditional P-i-N perovskite solar cells have achieved high efficiency over 25%, but the device structure is relatively complex, and generally requires expensive low-conductivity p-type organic semiconductors as hole transport materials. As a typical semiconductor, it is very important to realize the bipolar doping of methylamine lead iodine (CH3NH3PbI3) that is the light-absorbing layer of perovskite solar cell. Also, it is significant to develop perovskite cells with new device structure. Here, we chose lithium iodide (LiI) as the dopant and successfully grow p-type Li+ doped CH3NH3PbI3 (MAPbI3:Li) perovskite films with low resistivity (103 Ω•cm). The temperature-dependent photoluminescence, Hall effect and Kelvin probe force microscope (KPFM) results strongly confirmed that Li+ doping promotes the transformation of pristine weak n-type MAPbI3 to intentionally doped p-type film. Subsequently, the p-type MAPbI3 film is used as both the light absorption layer and hole transport layer, and form a PN heterojunction with n-type titanium dioxide (TiO2), which is used as the electron transport layer, to construct the heterostructural perovskite cell with a photoelectric conversion efficiency (PCE) of 10.43%. The electron beam induced current (EBIC) signal also strongly confirms the existence of the PN heterojunction and the new working mechanism of such new solar cells.

Layered double hydroxides (LDHs) have great advantages in the domain of energy storage because of their exchangeable anions and large specific surface area. Nevertheless, the shortcomings of their poor electrical conductivity, easy stacking of nanosheets, and large volume variation in the cycling processes lead to unsatisfactory cycling stability and rate performance, which severely limits their further application. Therefore, we generated homogeneous nanoarrays of NiFe-LDH on the surface of Ti

Although solution-processed organometal halide perovskites (OHPs) have attracted much attention for solar cell applications due to their superior photoelectric properties, such as strong band-edge absorption, small exciton binding energy, balanced electron-hole transport, superb charge carrier mobility, etc., their instability in the ambient air severely limits their commercial applications. Here, we introduce 4-Trifluorophenyl methylammonium cations (CF3PMA+) on the surface of 3D MAPbI3 films. Subsequently, the hydrophobic fluorinated 2D perovskite thin film is in-situ formed on 3D MAPbI3 surface. The van der Waals interaction between water molecules and the surface of the fluorinated 2D perovskite becomes weaker, which prevents the water molecules from entering the perovskite lattice and, therefore, improves the moisture resistance of the perovskite. In addition, the lifetime of the excited photocarriers becomes longer after 4-Trifluorophenyl methylammonium iodide (CF3PMAI) modification, which is conducive to carrier extraction and interface transport. The 2D/3D perovskite based solar cell (2D/3D PSCs) finally achieves a PCE of 15.01% by introducing CF3PMAI, and the unsealed PSCs can maintain 90% initial efficiency within 500 hrs. Our approach provides a moisture-resistant 2D/3D perovskite film heterostructure, where the hydrophobic fluorinated 2D perovskite layer acts as a protective layer.

Demand for simple and effective gas sensing sensors is growing rapidly due to the growing threat of triethylamine (TEA). Semiconductor tin oxide (SnO2) is one of the most widely used sensing materials for metal oxide gas sensors. In recent years, a lot of binary ternary compound researches have been carried out. In this paper, five different SnO2 samples were synthesized by simple synthesis method to understand the internal relationship and obtain different gas sensing characteristics. Based on the low temperature nitrogen adsorption tests and the atomic arrangement model, it can be inferred that different exposed surfaces play a key role in TEA sensing properties. In addition, the TEA sensing activity relationship of SnO2 exposed crystal faces is proposed as listed: (200) > (101) > (110).

Iron sulfides are promising anode materials for lithium ion batteries (LIBs) owe to their high theoretical capacity and low cost. However, unsatisfactory electronic conductivity, dissolution of polysulfides, and severe agglomeration during the cycling process limit their applications. To solve these issues, a ternary FeS2/Fe7S8@nitrogen-sulfur co-doping reduced graphene oxide hybrid (FeS2/Fe7S8@NSG) was designed and synthesized through a facile hydrolysis-sulfurization strategy, in which the FeS2/Fe7S8 could be well distributed upon the NSG. The NSG was believed to buffer the volume change and augment the electronic conductivity of the electrode, and the nano-dimensional FeS2/Fe7S8 particles with a diameter of 50–100 ​nm could shorten the ion-diffusion paths during the lithiation/delithiation process. Benefiting from synergistic contributions from nano-dimensional FeS2/Fe7S8 and flexible NSG, the FeS2/Fe7S8@NSG hybrid displayed a high initial capacity of ~1068 ​mAh g−1 at 200 ​mA ​g−1, good cycling stability (~898 ​mAh g−1 at 500 ​mA ​g−1 after 200 cycles) and high-rate performance. Further kinetic analysis corroborated that the introduction of NSG boosted the capacitive behavior. Above results indicate the potential applications of FeS2/Fe7S8@NSG hybrid in LIBs with low-cost and high energy density.

Improvements in the light-harvesting capacity and the carrier extraction are both significant to improve the photovoltaic performance of perovskite solar cells (PSCs). It has been proved that local...

Silicon-based materials with designed morphology and composite structure have received increasing interest in recent years due to the potential wide application for energy storage devices. However, these Si-based nanocomposites were usually synthesized and functionalized with other materials at a high temperature. Herein, one flocculent carbon network-twined C/Si/SiC nanocomposites were synthesized by a novel in-situ laser irradiation method using SiC targets as both a template and the source of C and Si. The fragmentation, decomposition and reshaping processes of bulk SiC to flocculent C/Si/SiC are simultaneously accomplished in one step, which can provide a more stable structure between epitaxial Si layer and C layer. What is more, due to the distinct laser-induced loose microstructure and flocculated carbon nanosheets, such nanocomposites exhibit a high specific surface area and hierarchically porous structure.

Summary Chiral halide perovskites have recently emerged as a class of potential optoelectronic materials. In this review, we mainly aim to provide a comprehensive understanding of chiral halide perovskite crystals for optoelectronic applications. An overview of the research background and advancement of chiral halide perovskites is described. Crystal structure, synthesis, and growth methods of chiral halide perovskite single crystals are demonstrated. Moreover, the characteristic properties and optoelectronic applications of chiral halide perovskites are systematically illustrated. Finally, future research opportunities and challenges of chiral halide perovskite single crystals and related devices are provided, concluding with our perspective on the burgeoning optoelectronic field.

In this work, we designed three series of tribo-couples based on amorphous carbon films including GLC, DLC and PLC that were modified by graphene quantum dots (GQDs). The tribo-testing environment was controlled at harsh conditions (like heavy load and high speed) in dry nitrogen atmosphere using bare and film-coated bearing steel balls as counterbodies, respectively. Through the tribochemical interactions, the self-mated DLC system obtained a surperlubricity state (μ = 0.01). During the whole sliding, the contact surface of the upper counterfacing ball was covered by 2D-layered carbon and graphitic lubricants induced via structural transformation of GQDs. Meanwhile, the tribofilm of the disc wear track was composed of a silica-like SiOx boundary layer and a multicomponent mixed-layer induced by tribochemistry. Compared to the self-mated DLC system, the structural boundary enriched with SiOx compounds was not formed at the bottom region of the tribofilm for the bare steel system; meanwhile, the disc wear track was covered by a thicker tribofilm containing plenty of degraded GQDs. This inferred the fact that the formation of a nanostructured sliding interface was the key to realize superlubricity. These discoveries successfully afforded a lubrication mechanism of GQDs for solid lubricant in applications of engineering and industry.

The room-temperature saturation recrystallization (RTSR) method has been extensively used to prepare all-inorganic lead halide perovskite (e.g., CsPbBr3) nanocrystals. Here, we revealed that the composition of the products prepared by the seemingly simple RTSR method could be extremely complex under different experimental parameters. The pH value of the solution and the protonation tendency of the amines influenced by the amounts and types of introduced amines, oleic acid, and water from the environment determined the composition of the final products. PbBr2, 2D Ruddlesden-Popper perovskites (RPPs) formed by perovskite layers separated by intercalating cations, and laurionite Pb(OH)Br would form under acidic, mildly acidic, and alkaline conditions, respectively. Based on the understanding of the formation mechanism, Pb(OH)Br microparticles with well-defined morphologies were prepared, which could be transformed into highly luminescent CH3NH3PbBr3 with the morphology unchanged. The protonated amine behaves as an intercalating layer during the formation of 2D RPPs. Phenylethylamine (PEA) was proven to be an appropriate amine to prepare pure RPP microplates because of its weaker alkalinity compared to aliphatic amines. The prepared (PEA)2PbBr4 RPP microplates showed strong deep-blue light emission with a PL peak at 415 nm, which could be fine-tuned by changing amines. This study proved the complex reaction pathways of the seemingly simple RTSR method and extended the RTSR method into the fabrication of 2D RPPs and laurionite with promising applications in optoelectronic devices.

Passivating defects to suppress recombination is a valid tactic to improve the performance of third-generation perovskite-based solar cells. Pb0 is the primary defect in Pb-based perovskites. Here,...

The fabrication of lead halide perovskites involves different types of organic solvents, which are not only harmful to the environment but also expensive. Herein, we present an ultimately green process to prepare CH3NH3PbBr3 (MAPbBr3) nanowires without using any organic solvents, acids, and alkalis. According to the formula of Pb(OH)Br, only PbBr2 and water are used to synthesize Pb(OH)Br. Subsequently, the Pb(OH)Br nanowires are converted into MAPbBr3 nanowires via a thermal evaporation technique (i.e., exposing Pb(OH)Br nanowires to MABr vapor). The prepared MAPbBr3 nanowires show comparable optical properties to those prepared using organic solvents. Such an ultimately green fabrication method can alleviate the environmental concerns and reduce the cost of perovskite commercialization.

Battery-supercapacitor hybrid (BSH) devices generally provide both high energy density and power density, but usually suffer from the serious electrochemical kinetics mismatch of cathodes and anodes mainly due to complex faradaic reactions of the unmatched battery-type electrodes used for charge storage, which inevitably degrade the rate capability and power density. To solve this, we propose a facile and efficient strategy of constructing carbon shells and oxygen vacancies. Oxygen-deficient Bi2O3 nanoflakes stabilized by N-doped carbon and supported on graphite fibers (GF@Bi2O3–NCs) were prepared to improve specific capacity, rate capability and cycling stability. The N/S-codoped carbon aerogels supported on graphite fibers (GF@NS-CAGs) provided a high capacitance of 312 F g−1 at 1 A g−1, which was mainly attributed to the microporous structure and high active N content. The flexible quasi-solid-state BSH device based on the GF@Bi2O3-NC anode and the GF@NS-CAG cathode with a stable voltage window of 2.3 V could deliver a remarkable capacity of 103 mA h g−1, an energy density of 118 W h kg−1 and capacity retention of 95.7% after 10 000 cycles, reflecting that this was a highly-efficient approach to develop high-performance flexible energy storage devices.

Mn-based Prussian blue analogue is regarded as one of the promising cathodes for sodium ions battery owing to its high theoretical capacity and low cost. However, the unstable structure during charging/discharging process and the poor cycle life hinder its commercial application. In this work, potassium ions stabilized hollow Mn-based Prussian blue analogue is synthesized through a simple sodium citrate assisted method using for cathode of sodium-ions batteries. Although unique hollow structure could suffer volume variation during charging/discharging process, the K+ is introduced to further stabilize its structure. The PBAs cathode exhibits a high reversible specific capacity of 128 mA h g−1 at 50 mA and superior rate performance of 72 mA h g−1 at a high current density of 3200 mA g−1, which is attributed to its stable structure and enhanced sodium ions transport kinetics. Ex-situ XRD/Raman tests and electrochemical measurements further prove the synergistic effect of various alkali ions (K+/Na+) and unique hollow structure. They work together to improve the structural stability and promote sodium ions diffusion rate of Mn-based PBAs.

In this study, for the first time, a Cu+-doped PbBrOH red phosphor (PbBrOH:Cu) was successfully synthesized by a hydrothermal method. The crystal structure, microstructure, optical properties, luminescence mechanism, and environmental stability of the PbBrOH:Cu phosphor were discussed in detail. PbBrOH and PbBrOH:Cu phosphor synthesized by the hydrothermal method are needle-like transparent grains. The excitation wavelengths of the PbBrOH and PbBrOH:Cu phosphor were both 353 nm. Under the excitation of this wavelength, weak blue emission and excellent red emission were observed. Based on first-principles calculation, ultraviolet and visible (UV-vis) spectrophotometry, and ultraviolet photoelectron spectroscopy (UPS) analysis, we concluded that the luminescence type of the phosphors was bandgap luminescence. The addition of Cu+ significantly reduced the bandgap, produced defect levels, and promoted the electron transition between the bandgaps, which led to the strong red emission of PbBrOH:Cu under UV excitation. It is worth noting that the PbBrOH:Cu phosphor shows excellent environmental stability and excellent luminescence performance when it is used in organic solvent immersion experiments and manufacturing LED lamp beads. Therefore, the PbBrOH:Cu phosphor synthesized in this study is expected to be a strong candidate as the red phosphor component in white LEDs.

Oxygen vacancies are highly important for photocatalytic performance in bismuth oxychloride, but their preparation is limited to vacuum roasting and hydrogen annealing techniques at high temperatures (200–400 °C). Here we report a straightforward polyvinyl pyrrolidone (PVP)-mediated pathway for the synthesis of BiOCl nanoclusters (BiOCl-NCs) at room temperature, which can spontaneously and rapidly convert surface hydroxyl groups into oxygen vacancies during the photoactivation process. In situ FT-IR results present the formation process of oxygen vacancies and theoretical calculation results demonstrate that after the introduction of oxygen vacancies, a fresh electron donor level formed in the band gap of BiOCl, which is beneficial for visible-light photon energy absorption. As expected, the resulting BiOCl-NCs–OV exhibited remarkable photocatalytic capacity for degradation of organic dyes, reduction of toxic metal ions under all pH conditions and enhanced photocatalytic hydrogen evolution rate (1.21 mmol g−1 h−1) because of in situ generated oxygen vacancies, enhanced light absorption capability, and improved separation and transfer effectiveness of photoexcited charge carriers. Our protocol may open up new ways to design progressive photocatalysts for environment-related applications.

Lithium-ion capacitors (LICs) are hybrid energy storage devices with a capacitor-type cathode and battery-type anode, which bridge the gap between conventional high-energy lithium-ion batteries and...

Inorganic perovskite cesium lead bromide (CsPbBr3) gets extensive attention due to its superb stability and moisture-tolerance feature. Here, solution-processed CsPbBr3 perovskite films and their based solar cells were fabricated in ambient condition. The effect of post-annealing on the properties of the CsPbBr3 film grown and the photoelectric performance of perovskite solar cells (PSCs) have been systematically investigated, which enhances the device power conversion efficiency (PCE) from 2.67 to 5.20%. Moreover, by doping mesoporous TiO2 (m-TiO2) with reduced graphene oxide (RGO), the PCE of solar cells attained an apparent enhancement and finally improved to 7.08%. Not only high-quality CsPbBr3 perovskite films but also high-performance mesoporous PSCs were obtained by film post-annealing and electron transport layer (ETL) doping, which were all fabricated in ambient conditions.

Perovskite solar cells (PSCs) have attracted considerable attention as a prominent photovoltaic technology, yet the state-of-the-art PSCs still contain thermally unstable methylammonium (MA) cation...