Search

Cu2ZnSn(S,Se)4 (CZTSSe) photovoltaic (PV) technology has attracted much attention due to its cost efficiency, non-toxic nature, and use of earth-abundant elements.

Deciphering the atomic and electronic structures of interfaces is key to developing state-of-the-art perovskite semiconductors. However, conventional characterization techniques have limited previous studies mainly to grain-boundary interfaces, whereas the intragrain-interface microstructures and their electronic properties have been much less revealed. Herein using scanning transmission electron microscopy, we resolved the atomic-scale structural information on three prototypical intragrain interfaces, unraveling intriguing features clearly different from those from previous observations based on standalone films or nanomaterial samples. These intragrain interfaces include composition boundaries formed by heterogeneous ion distribution, stacking faults resulted from wrongly stacked crystal planes, and symmetrical twinning boundaries. The atomic-scale imaging of these intragrain interfaces enables us to build unequivocal models for the ab initio calculation of electronic properties. Our results suggest that these structure interfaces are generally electronically benign, whereas their dynamic interaction with point defects can still evoke detrimental effects. This work paves the way toward a more complete fundamental understanding of the microscopic structure–property–performance relationship in metal halide perovskites.

The first challenge in the commercialization of perovskite solar cells (PSCs) is how to easily fabricate large-scale, high-quality perovskite films. Although some methods have been developed for the fabrication of large-scale films, the film quality still needs to be improved. The MA0 healing method, as a post-processing technique, can be perfectly combined with other large-scale methods. However, determining the mechanism of the whole process is crucial for commercial production and subsequent research. Herein, we summarize the research progress on the MA0 healing method. Firstly, we introduce the interaction during the liquification process including the interaction of amines with Pb2+, the generation of hydrogen bonds, the influence of H2O, and the reactions between different amines. Then, we systematically discuss the dynamic mechanism of adsorption and desorption. Finally, several aspects that need to be further clarified are proposed.

Featuring sulfonyl, an organic small molecule, 3-ethylbenzo[d]isothiazole 1,1-dioxide (PSAD), is introduced to effectively passivate defects in perovskite films via hydrogen bonding and coordination bonding interactions, affording devices with higher efficiency and better operational stability.

Metal-cation defects and halogen-anion defects in perovskite films are critical to the efficiency and stability of perovskite solar cells (PSCs). In this work, a random polymer, poly(methyl methacrylate-co-acrylamide) (PMMA-AM), was synthesized to serve as an interfacial passivation layer for synergistically passivating the under-coordinated Pb

Molecular doping is an of significance approach to reduce defects density of perovskite and to improve interfacial charge extraction in perovskite solar cells. Here, we show a new strategy for chemical doping of perovskite via an organic small molecule, which features a fused tricyclic core, showing strong intermolecular π-Pb 2+ interactions with under-coordinated Pb 2+ in perovskite. This π-Pb 2+ interactions could reduce defects density of the perovskite and suppress the nonradiative recombination, which was also confirmed by the density functional theory calculations. In addition, this doping via π-Pb 2+ interactions could deepen the surface potential and downshift the work function of the doped perovskite film, facilitating the hole extraction to hole transport layer. As a result, the doped device showed excellent efficiency of 21.41% with ignorable hysteresis. This strategy of fused tricyclic core-based doping provides a new perspective for the design of new organic materials to improve the device performance.

Solvents employed for perovskite film fabrication not only play important roles in dissolving the precursors but also participate in crystallization process. High boiling point aprotic solvents with O-donor ligands have been extensively studied, but the formation of a highly uniform halide perovskite film still requires the participation of additives or an additional step to accelerate the nucleation rate. The volatile aliphatic methylamine with both coordinating ligands and hydrogen protons as solvent or post-healing gas facilitates the process of methylamine-based perovskite films with high crystallinity, few defects, and easy large-scale fabrication as well. However, the attempt in formamidinium-containing perovskites is challenged heretofore. Here, we reveal that the degradation of formamidinium-containing perovskites in aliphatic amines environment results from the transimination reaction of formamidinium cation and aliphatic amines along with the formation of ammonia. Based on this mechanism, ammonia is selected as a post-healing gas for a highly uniform, compact formamidinium-based perovskite films. In particular, low temperature is proved to be crucial to enable formamidinium-based perovskite materials to absorb enough ammonia molecules and form a liquid intermediate state which is the key to eliminating voids in raw films. As a result, the champion perovskite solar cell based on ammonia post-healing achieves a power conversion efficiency of 23.21% with excellent reproducibility. Especially the module power conversion efficiency with 14 cm2 active area is over 20%. This ammonia post-healing treatment potentially makes it easier to upscale fabrication of highly efficient formamidinium-based devices.

Summary The studies of perovskite film in the perovskite solar cells (PSCs) mainly focus on their crystallization and growth, but the reactions that happen in the precursor solutions are still not very clear, which is leading to the bad reproducibility for high-efficient devices. We demonstrated that, in the methylammonium- and formamidinium-mixed organic cation perovskite solution, the methylamine molecule could be first generated from the deprotonation of methylammonium iodide, and then condensate with formamidinium iodide to form N-methyl formamidinium iodide and N, N′-dimethyl formamidinium iodide. The triethyl borate was carried out as a stabilizer to restrain the deprotonation of methylammonium iodide in the precursor solutions, resulting in the elimination of the impurity phase in perovskite films. We think that the introduction of stabilizer in the perovskite precursor solution will become a common strategy for mixed-organic-cation PSCs in the future to improve the reproducibility and efficiency.

In solution-processed organic-inorganic halide perovskite films, halide-anion related defects including halide vacancies and interstitial defects can easily form at the surfaces and grain boundaries. The uncoordinated lead cations produce defect levels within the band gap, and the excess iodides disturb the interfacial carrier transport. Thus these defects lead to severe nonradiative recombination, hysteresis, and large energy loss in the device. Herein, polyacrylonitrile (PAN) was introduced to passivate the uncoordinated lead cations in the perovskite films. The coordinating ability of cyano group was found to be stronger than that of the normally used carbonyl groups, and the strong coordination could reduce the I/Pb ratio at the film surface. With the PAN perovskite film, the device efficiency improved from 21.58 % to 23.71 % and the open-circuit voltage from 1.12 V to 1.23 V, the ion migration activation energy increased, and operational stability improved.

Developing dopant-free hole transporting materials (HTMs) and passivating defects in perovskite films are two significant themes to realize efficient and stable perovskite solar cells (PSCs). Compared to various individual endeavors for either of them, enabling both via a single material is more interesting but certainly challenging. In this report, we develop dopant-free polymer HTMs bearing amino pendants as passivating groups for improved efficiency and stability of PSCs. The bifunctional polymers present simultaneous main-chain (donor–acceptor conjugated backbone) hole extraction/transport and side-chain (amino group) defect passivation at the perovskite/HTM interface. Moreover, with an increased content of amino pendants, the polymers exhibit enhanced hole mobility and defect passivation ability, advancing device efficiency and stability. As a result, PSCs using the dopant-free polymer HTM achieve an efficiency approaching 19%, with impressive stability when testing at a relative humidity of 85%, by heat at 80 °C, or under continuous light illumination. This work demonstrates that amino functionalization at the side chain of polymers is a promising method to develop dopant-free HTMs accompanied by defect passivation effects for high-performance and durable PSCs.

In the past ten years, perovskite solar cells (PSCs) have achieved tremendous success, with the efficiency rivalling that of conventional silicon-based devices. To promote commercialization, lowering the production cost and reducing the complexity of the process would make the devices more competitive and thus are highly required. In this respect, inverted hole-transport-layer-free (HTL-free) PSCs were developed and have been attracting extensive attention. To date, the efficiency of inverted HTL-free PSCs has surpassed 20%, and 90% of the initial efficiency can be retained after 1000 h of continuous illumination, showing their great application potential. In this mini-review, we summarize the development and progress of inverted HTL-free PSCs. The universality of inverted HTL-free structures (including flexible and semi-transparent devices) and stability are also discussed. Finally, promising research directions are suggested to further advance the inverted HTL-free PSCs.

Summary Here, we sucessfully demonstrate the continuous functionalization of grain boundaries (GBs) in CH 3 NH 3 PbI 3 (MAPbI 3 ) organic-inorganic halide perovskite (OIHP) thin films with a triblock copolymer that contains rationally selected hydrophilic-hydrophobic-hydrophilic symmetric blocks. The addition of the triblock copolymer into the precursor solution assists in perovskite solution crystallization, resulting in ultrasmooth thin films with GB regions that are continuously functionalized. Tuning of the thickness of the functionalized GBs is realized, leading to MAPbI 3 OIHP thin films with simultaneously enhanced optoelectronic properties and environmental (thermal, moisture, and light) stability. The resulting perovskite solar cells show high stabilized efficiency of 19.4%, most of which is retained (92%) upon 480-hr 1-sun illumination. This approach is generic in nature, and it can be extended to a wide range of OIHPs and beyond.

Graphene-wrapped iron carbide nanoparticles (Fe3C@G) are employed as an alternative counter electrode to Pt in dye-sensitized solar cell via a convenient magnetic field induced assembly method. Benefit from the novel binder-free electrode fabrication route, the Fe3C@G nanosheets orderly are deposited on the FTO glass to form an effective catalyst layer with both favorable catalytic ability and electron migration rate. Comparable photovoltaic conversion efficiency with Pt endows the Fe3C@G a promising counter electrode for low cost but high performance dye-sensitized solar cells. Moreover, the magnetic field induced assembly method also shows potential application for other magnetic materials towards counter electrode.

Interface engineering is a crucial strategy to improve the performance of the perovskite solar cells. The introduction of excess PbI2 with simple mixing method is widely used, but unfortunately its underlying mechanism is still unclear. The main reason is the lack of direct evidence with precise control of the PbI2 distribution. Herein, a program-controlled pulsed H2O vapor exposure/purge method was developed to evenly generate thin PbI2 layer on the film surface. Based on this method, it was found that different PbI2 locations play a different effects on the photovoltaic performance of the perovskite solar cells. In the normal device structure, the performance improvement is owing to the passivation effect, while in the inverted device structure, the energy level alignment plays a more dominant role. The discoveries based on the PbI2 location controllable method are conducive to our new understanding of the traditional PbI2-rich system and thus can be a direction towards highly efficient perovskite solar cells.

The stability of the perovskite/electron transport layer (ETL) interface is critical for perovskite solar cells due to the presence of ultraviolet (UV) light in the solar spectrum. Herein, we have studied the decomposition process and performance evolution of the perovskite layer in contact with different ETLs under strong ultraviolet irradiation. The normally used SnO2 layer has lower photocatalytic activity in comparison with the TiO2 layer, but the perovskite/SnO2 interface is still severely decomposed along with the formation of hole structures. Such UV light-induced decomposition, on the one hand, leads to the decomposition of the perovskite phase into PbI2 and more seriously, the formed hole structure significantly limits the carrier injection at the interface owing to the separation of the perovskite active layer from ETLs. Under the same conditions, the perovskite/PCBM interface is very stable and maintains a highly efficient carrier injection. There is no significant efficiency degradation of the encapsulated PCBM-based devices measured outdoors for about three months.

The addition of a polar-hydrophobic methylammonium trifluoroacetate ionic liquid tailors the hydrophobicity of halide-perovskite precursor solutions and assists in grain growth. This unique additive also functionalizes the grain boundaries via polar-polar interactions, thereby enhancing the optoelectronic properties and chemical stability of perovskites. This study opens the door to the solution hydrophobicity control towards high-performance perovskite devices.

We report here the discovery of a fancy interaction between cesium iodide (CsI) and methylamine (CH3NH2) due to the presence of the hydrogen bond. The formed CsI·xCH3NH2 is a liquid phase, which facilitates the large scale fabrication of highly uniform cesium-containing perovskite films with strong (110) preferred orientation by the CH3NH2 gas healing process. With this method, at most 10% nonpolar Cs cations could fully dope into the crystal lattice and extremely enhance the interaction of the inorganic framework with a more symmetrical PbI6 octahedron, resulting in obvious improvement in moisture stability under continuous illumination.

The efficiency of a perovskite solar cell is highly affected by the crystal quality and morphology of its perovskite layer. A facile strategy of using blended organic additives to regulate the film's crystallinity and coverage is studied in this work. The coordination behavior and sublimation temperature of the additives are the essential characteristics which determine the quality of the perovskite films. By introducing a certain amount of MACl, a kind of crystallinity-preferred additive, to partially replace MAAc, a coverage-preferred additive, the film's crystallinity has been obviously improved at no expense of coverage, which results in a lower trap density, higher efficiency and better stability.

Methylamine-induced thin-film transformation at room-temperature is discovered, where a porous, rough, polycrystalline NH4PbI3 non-perovskite thin film converts stepwise into a dense, ultrasmooth, textured CH3NH3PbI3 perovskite thin film. Owing to the beneficial phase/structural development of the thin film, its photovoltaic properties undergo dramatic enhancement during this NH4PbI3-to-CH3NH3PbI3 transformation process. The chemical origins of this transformation are studied at various length scales.

Highly efficient planar heterojunction perovskite solar cells (PHJ–PSCs) with a structure of ITO/PEDOT:PSS/CH3NH3PbI3–xClx/PCBM/C60/Ag was fabricated, in which the compact and pinhole-free CH3NH3PbI3–xClx perovskite thin film was obtained using a mixture of precursors containing lead iodide (PbI2), lead chloride (PbCl2), and methylammonium iodide (CH3NH3I) at an optimized ratio of 1:1:4. The morphology and formation process of CH3NH3PbI3–xClx thin film was closely related to the annealing temperature and time, which would result in the controllable performance for the PHJ–PSC devices. The morphology, crystallization process, and element analysis suggested that the chlorine gradually diffused and sublimated from the film surface while the iodine moved to the surface, together with the removal of the pinholes in the film. The PHJ–PSCs with the as-prepared CH3NH3PbI3–xClx thin film showed good performance and excellent repeatability. The power conversion efficiency (PCE) up to 14.03% was achieved without obv...

An easy and scalable methylamine (MA) gas healing method was realized for inorganic cesium-based perovskite (CsPbX3 ) layers by incorporating a certain amount of MAX (X=I or Br) initiators into the raw film. It was found that the excess MAX accelerated the absorption of the MA gas into the CsPbX3 film and quickly turned it into a liquid intermediate phase. Through the healing process, a highly uniform and highly crystalline CsPbX3 film with enhanced photovoltaic performance was obtained. Moreover, the chemical interactions between a series of halides and MA gas molecules were studied, and the results could offer guidance in further optimizations of the healing strategy.

Doping and/or alloying in the various layers in perovskite solar cells (PSCs) is playing a key role in the success of this new photovoltaic (PV) technology. Here we present a brief review of doping and alloying approaches used to enhance the efficacy of the hybrid organic–inorganic perovskite (HOIP) layer, the electron-transporting layer (ETL), the hole-transporting layer (HTL), and the electrode layers in PSCs. While the effectiveness of these approaches is beyond doubt, the fundamental understanding of doping and alloying in the majority of the cases is lacking. This presents vast research opportunities in elucidating the roles of doping and alloying, and the rational design and implementation of these approaches for enhanced PSCs performance.

We find that there exists an ion exchange phenomenon in the precursor solutions for perovskite films. Despite the different ion introduction routes, the samples fabricated from precursor solutions with same ion molar ratio finally present similar properties. This finding illuminates a wide selectivity of reactants for the preparation of perovskite films.

Unlike traditional MAPbI3, methods for large scale fabrication of high quality FA based perovskite films are still lacking. In this paper, the organic cation exchange temperature is optimized toward the formation of highly uniform FA based perovskite films. Under optimized conditions, the cation diffusion speed within the perovskite film is extremely enhanced and the time constant is reduced ∼20 times. The shortened dipping time and mild reaction conditions can efficiently restrict the undesirable phase transition and preserve the film morphology. Fundamental insight into this solid–liquid reaction has been obtained by combining photophysical, XRD and SEM characterizations. The optimized FAxMA1−xPbI3 with x ≈ 0.75 presents the highest efficiency of 15.5% with less hysteresis.

Formamidinium lead triiodide (HC(NH2)2PbI3 or FAPbI3) is gaining increasing interest in the field of mesoscopic perovskite solar cells (PSCs) for its broader light absorption compared with the more widely studied CH3NH3PbI3 (MAPbI3). Because FAPbI3 has two polymorphs (“black” α-FAPbI3 and “yellow” δ-FAPbI3) at ambient temperature, where α-FAPbI3 is the desirable photoactive perovskite phase, it becomes particularly important to suppress the formation of the nonperovskite δ-FAPbI3 for achieving high efficiency in FAPbI3-based mesoscopic PSCs. In this study, we demonstrate that the judicious use of low-volatility additives in the precursor solution assists in the evolution of α-FAPbI3 through the formation of non-δ-FAPbI3 intermediate phases, which then convert to α-FAPbI3 during thermal annealing. The underlying mechanism involved in the additive-modulated evolution of α-FAPbI3 upon mesoporous TiO2 substrates is elucidated, which suggests guidelines for developing protocols for the fabrication efficient FA...

We report herein the discovery of methylamine (CH3NH2) induced defect-healing (MIDH) of CH3NH3PbI3 perovskite thin films based on their ultrafast (seconds), reversible chemical reaction with CH3NH2 gas at room temperature. The key to this healing behavior is the formation and spreading of an intermediate CH(3)NH(3)PbI(3)xCH(3)NH(2) liquid phase during this unusual perovskite-gas interaction. We demonstrate the versatility and scalability of the MIDH process, and show dramatic enhancement in the performance of perovskite solar cells (PSCs) with MIDH. This study represents a new direction in the formation of defect-free films of hybrid perovskites.

CH3NH3PbI3 (MAPbI(3)) perovskite thin films that are solution-processed using either a one-step or two-step conventional method typically contain a significant number of defects (voids, pinholes) or PbI2 impurities, which have a detrimental effect on the performance of planar perovskite solar cells (PSCs) fabricated using those films. To overcome this issue, we show that enhancement of the solid-state reaction between inorganic-organic precursors is an effective route for the growth of compact, phase-pure MAPbI(3) perovskite thin films with no voids or pinholes. To ensure uniform solid-state conversion (MAI + PbI2 -> MAPbI(3)) across the entire film thickness, a new successive spin coating/annealing (SSCA) process is used, where MAI is repeatedly infiltrated into a nanoporous PbI2 film, followed by thermal annealing. The mechanisms involved in the SSCA process are elucidated by monitoring the evolution of the phases during the reaction. Owing to these desirable characteristics (high-purity, full-coverage, enhanced smoothness and compactness) of the SSCA MAPbI(3) films, planar PSCs based on these perovskite thin films delivered a maximum power conversion efficiency (PCE) close to 15%. Furthermore, PSCs fabricated using partially converted nanoporous PbI2 thin films delivered a surprising PCE approaching 10%, suggesting continuous MAPbI(3) phase formation throughout the entire film at each spin coating/annealing process. The advantages gained from enhancing the solid-state precursor reactions allow better control of the growth of the perovskite making the SSCA process more robust.

Recently, organometal halide perovskite solar cells (PSCs) have attracted considerable attention because of their extremely high power conversion efficiency (PCE). Not only does the performance of PSCs depend on the material properties of the device involved, but also it is dramatically affected by the nature of their interfaces present, which highly affect the carriers' extraction, transport and recombination. Therefore, interface engineering, a novel approach towards high-performance PSCs, has attracted increasing interest. In this review, we focus on recent advances in the study of PSC interfaces, which have resulted in improved device performance.

A Cu3Ge/Ge@G aerogel was employed as an anode for a lithium-ion battery by a simple pyrolysis of a CuGeO3 nanowire and graphene oxide nanosheet mixture. It is demonstrated that both the Cu3Ge nanoparticles and graphene nanosheets act as conductive buffers to accelerate the electron migration rate and enhance the cycling stability of the electrode.

Methylammonium lead trihalide perovskites are attracting intensive interest due to its high photovoltaic performance, low cost and one-step solution processability. Since the morphology of the perovskite thin films play the central role on the cell performance, a plethora of methods have been developed to fabricate uniform perovskite film. Herein, we demonstrate that an innovative approach by applying mixed lead salts (PbI2 + PbCl2) to facilitate reproducible fabrication of compact perovskite thin film. It is proposed that rapid reaction kinetics of PbI2 with MAI enables preformation of perovskite within the intermidiate film matrix, working as homogeneously located domains for squential growth of the PbCl2-derived perovskite. The as-prepared perovskite film exhibited a overall textured crystal morphology and superior compactness, which enables excellent light absorption and long-time preservation of photogenerated charge carriers and therefore exhibits 11% efficiency in planar-structured solar cells. The annealing testing shows the film also possesses very stable morphology upon long-time heating, indicative of the insensitivity of our new protocol to the preparation condition and also the promising thermal stability of its based solar cells. The simplicity of the one-step solution-processing and the high morphology stability of the as-prepared perovskite film endow this mixing lead salts method with feasibility of the large-scale fabrication.

The nanocomposites of cobalt selenide and nickel selenide (Co0.85Se/Ni0.85Se) were successfully fabricated on FTO glass by a facile co-electrodeposition method at ambient temperature. Nanocomposite films were used as electrocatalysts in dye-sensitized solar cell counter electrodes for regeneration of both iodide/triiodide and cobalt(II/III) redox couples. Co0.85Se/Ni0.85Se were mainly composed of nanoflakes and nanoparticles. It is noted that such nanostructure generated by nanoparticles embedded with 2D nanoflakes led to high active sites and was accessible to cobalt(II/III) electrolyte, delivering better catalytic activity for the reduction of larger volume cobalt(II/III). As a result, for cobalt(II/III) electrolyte, the Co0.85Se/Ni0.85Se based dye-sensitized solar cell performed significantly improved efficiency than that of Pt and Co0.85Se. Meanwhile, the Co0.85Se/Ni0.85Se based dye-sensitized solar cell held comparable energy conversion efficiency to that of Pt and Co0.85Se for iodide/triiodide electrolyte.

A new sequential-vapour-deposition method is demonstrated for the growth of high-quality CH3NH3PbI3 perovskite films. This has enabled the all-vapour, low-temperature fabrication of hole-conductor-free planar perovskite solar cells consisting of only a CH3NH3PbI3/C60 bi-layer sandwiched between two electrical contacts, with a power conversion efficiency of 5.4%.

An aramid membrane with good electrolyte wettability, high ionic conductivity, excellent inflame retarding property and superior thermal resistance has been successfully fabricated via a facile papermaking process for improving the safety characteristic of lithium ion battery. The aramid membrane endows the lithium cobalt oxide (LiCoO2)/graphite cell superior cycle performance and better interfacial flexibility. In addition, the lithium iron phosphate (LiFePO4)/lithium cell using such aramid membrane exhibited stable charge-discharge profiles and satisfactory cycling stability even at an elevated temperature of 120 degrees C. These fascinating characteristics and facile papermaking method provide potential application as separator in high energy lithium ion battery. (C) 2013 The Authors. Published by Elsevier B.V. All rights reserved.

In the germanium–carbon nanotubes–copper monolith anode, the carbon nanotube (CNT) network enhances the electron migration in the electrode and the elastic matrix buffers the volume expansion of Ge active particles. The improved rate and cycling performance endow this elastic monolith as an attractive candidate for lithium batteries' anode.

The α→δ phase transition, which occurs favorably in planar films of a black α-HC(NH2)2PbI3 (α-FAPbI3) perovskite in the amibent, is retarded when α-FAPbI3 is deposited upon mesoporous TiO2 scaffolds. It is hypothesized that this is due to the synergistic effect of the partial encapsulation of α-FAPbI3 by the mesoporous TiO2 and the elevated activation energy for the transition reaction associated with the substantial increase of the TiO2/α-FAPbI3 interfacial area in the mesoscopic system.

Well-defined DTBDT crystal microribbons were fabricated by a solution processing method named as solvent vapor diffusion directly on the surface. This procedure is based on exposing a drop cast solution to a saturated solvent vapor atmosphere and allows to tune the dimensions of the ribbons simply by controlling the concentration of the solution. The structural study indicates single crystallinity and a molecular organization in the ribbons that is considered to be favorable for the carrier transport along ribbon axis. In the device, individual crystal DTBDT organic field-effect transistors exhibit mobilities as high as 3.2 cm2 V–1 s–1 and on/off ratios up to 1 × 106. This processing approach can be further exploited for a broad range of other (macro)molecular semiconductors and additionally bears great potential for practical applications.

Graphene oxide (GO) nanosheets and polyoxometalate clusters, H(3)PW(12)O(40) (PW), were co-assembled into multilayer films via electrostatic layer-by-layer assembly. Under UV irradiation, a photoreduction reaction took place in the films which converted GO to reduced GO (rGO) due to the photocatalytic activity of PW clusters. By this means, uniform and large-area composite films based on rGO were fabricated with precisely controlled thickness on various substrates such as quartz, silicon, and plastic supports. We further fabricated field effect transistors based on the composite films, which exhibited typical ambipolar features and good transport properties for both holes and electrons. The on/off ratios and the charge carrier mobilities of the transistors depend on the number of deposited layers and can be controlled easily. Furthermore, we used photomasks to produce conductive patterns of rGO domains on the films, which served as efficient microelectrodes for photodetector devices.

We present investigations on the microcosmic self-assembly process of new synthesized amphiphilic DMAPNPP molecules. During the temperature decrease and solvent evaporation of the amphiphilic molec...

High-quality formamidinium lead iodide (FAPbI3) perovskite thin films are fabricated via organic cation exchange. With ammonia lead iodide (NH4PbI3) as the starting material, the NH4(+) in NH4PbI3 could be gradually substituted by FA(+) in formamidine acetate (FA-Ac) and simultaneously transformed to the pure phase α-FAPbI3 at elevated temperature.

We demonstrate the feasibility of a nonsalt-based precursor pair--inorganic HPbI3 solid and organic CH3NH2 gas--for the deposition of uniform CH3NH3PbI3 perovskite thin films. The strong room-temperature solid-gas interaction between HPbI3 and CH3NH2 induces transformative evolution of ultrasmooth, full-coverage perovskite thin films at a rapid rate (in seconds) from nominally processed rough, partial-coverage HPbI3 thin films. The chemical origin of this behavior is elucidated via in situ experiments. Perovskite solar cells, fabricated using MAPbI3 thin films thus deposited, deliver power conversion efficiencies up to 18.2%, attesting to the high quality of the perovskite thin films deposited using this transformative process.

Polyaniline submicrometer-sized tubes with controllable morphology have been synthesized by chemical oxidative polymerization of aniline with the aid of sodium dodecylbenzenesulfonate. The products were characterized by field-emission scanning electron microscopy, transmission electron microscopy and Fourier transform infrared spectroscopy, respectively. The effects of the concentrations of sodium dodecylbenzenesulfonate, reaction temperatures and growth conditions on the morphologies of polyaniline submicrometer-sized tubes have been investigated.

A novel one-step approach for synthesizing highly luminescent oil soluble carbon dots (quantum yield: 53%) and water-soluble carbon dots is introduced. The superior luminescence efficiency, together with the simple, rapid, and reproducible synthesis method will facilitate fundamental studies and promising practical applications of these carbon-based quantum dots.

We synthesized a series of compounds by changing the plasma atmosphere. Besides manganese nanoparticles using hydrogen and helium as the plasma atmosphere, sheet-like MnC 8 and spherical Mn 6 N 2.58 are also obtained adopting liquid steam as plasma atmosphere entirely by modifying arc plasma method. The compositions, structure and morphologies of the product were determined by X-ray diffraction (XRD) and Transmission electron microscopy (TEM). Finally, we preliminarily discussed the reason of the effect of the atmosphere to the final products of arc plasma method.

A facile chemical method has been developed to synthesise highly efficient functionalized carbon dots; when illuminated with 407 nm light, both the solution and film emitted white-light directly.