Search

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. [ABSTRACT FROM AUTHOR]

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 CH3NH3PbI3⋅ xCH3NH2 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. [ABSTRACT FROM AUTHOR]

CH3NH3PbI3 (MAPbI3) 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 MAPbI3 perovskite thin films with no voids or pinholes. To ensure uniform solid-state conversion (MAI + PbI2→ MAPbI3) 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 MAPbI3 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 MAPbI3 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. [ABSTRACT FROM AUTHOR]

In a TiO2-perovskite heterojunction solar cell (TiO2-PHSC), besides the perovskite CH3NH3PbX3, TiO2 as one side of the TiO2/CH3NH3PbX3 heterojunction also plays an important role in the photovoltaic effect. In order to improve the performance of the TiO2-PHSC with the structure of glass/FTO/compact TiO2/mesoporous TiO2/CH3NH3PbI3- xCl x /poly-TPD (poly( N, N ′-bis(4-butylphenyl)- N, N ′-bis(phenyl)benzidine))/Au, a 2 nanometer thick Cs2CO3 layer is thermally evaporated on the mesoporous TiO2 layer. The short-circuit current density ( Jsc) raises from 17.7 mA cm-2 to 18.9 mA cm-2, the open-circuit voltage ( Voc) from 0.81 V to 0.87 V, and the fill factor (FF) from 55.2% to 67.3%; as a result, the power conservation efficiency (PCE) increases from 8.0% to 11.1% under AM 1.5G solar illumination (100 mW cm-2). Moreover, in a TiO2-PHSC free of mesoporous TiO2, where Cs2CO3 is evaporated on the compact TiO2 layer, the Jsc, Voc, FF and PCE values increase from 16.0 mA cm-2, 0.83 V, 50.8% and 6.7% to 17.9 mA cm-2, 0.90 V, 59.3%, and 9.5%, respectively. The reasons of the PCE increase for either the first kind of TiO2-PHSC or the mesoporous-TiO2-free TiO2-PHSC with a nanometer-thick Cs2CO3 layer on mesoporous TiO2 or compact TiO2 are discussed. (© 2014 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Formamidinium (FA) lead triiodide perovskite with chlorine addition (NH2CH=NH2PbI(3−x)Clx) is employed as a light harvester in mesoscopic solar cells for the first time. It is demonstrated that a phase-pure FAPbI(3−x)Clx perovskite layer can be synthesized using a one-step solution-process at 140 °C, and the resultant solar cells deliver a maximum power conversion efficiency of 7.51%, which is the most efficient formamidinium-lead-halide perovskite mesoscopic solar cell employing a polymer hole-transporting layer. The effects of the thermal annealing temperature on the quality/morphology of the perovskite layer and the solar cells performance are discussed. The advantages offered by the one-step solution-processing method and the reduced bandgap make FAPbI(3−x)Clx perovskites an attractive choice for future hybrid photovoltaics. [ABSTRACT FROM AUTHOR]

A newnearly cubic NH2CHNH2PbI3(FAPbI3) perovskite was synthesized for the mesoscopicsolar cells. The measured band gap of bulk FAPbI3is 1.43eV and it is therefore potentially superior than the CH3NH3PbI3(MAPbI3) as the light harvester.A homogeneous FAPbI3perovskite layer was deposited onthe TiO2surface by utilizing the in situ dipping technology.As a result, a high efficiency of 7.5% was achieved using P3HT asthe hole transport material. The nearly cubic crystal structure andappropriate band gap render this new FAPbI3perovskiteextremely attractive for next generation high-efficiency low-costsolar cells. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Carbonyl‐containing aromatic ketones or aldehydes have been demonstrated to be effective defect passivators for perovskite films to improve performances of perovskite solar cells (PSCs). It has been claimed that both π‐electrons within aromatic units and carbonyl groups can, separately, interact with ionic defects, which, however, causes troubles in understanding the passivation mechanism of those aromatic ketone/aldehyde molecules. Herein, we clarify the effect of both moieties in one molecule on the defect passivation by investigating three aromatic aldehydes with varied conjugation planes, namely, biphenyl‐4‐carbaldehyde (BPCA), naphthalene‐2‐carbaldehyde (NACA) and pyrene‐1‐carbaldehyde (PyCA). Our findings reveal that the π‐electrons located in the conjugated system do not directly present strong passivation for defects, but enhance the electron cloud density of the carbonyl group augmenting its interaction with defect sites; thereby, with the extended conjugation plane of the three molecules, their defect passivation ability is gradually improved. PSCs incorporating PyCA with the most extended π‐electrons delocalization achieve maximum power conversion efficiencies of 25.67 % (0.09 cm2) and 21.76 % (14.0 cm2). Moreover, these devices exhibit outstanding long‐term stability, retaining 95 % of their initial efficiency after operation for 1000 hours at the maximum power point. [ABSTRACT FROM AUTHOR]

The interface modification between perovskite and electron transport layer (ETL) plays a crucial role in achieving high performance inverted perovskite photovoltaics (i‐PPVs). Herein, non‐fullerene acceptors (NFAs), known as Y6‐BO and Y7‐BO, were utilized to modify the perovskite/ETL interface in i‐PPVs. Non‐polar solvent‐soluble NFAs can effectively passivate surface defects without structural damage of the underlying perovskite films. Additionally, the improved phenyl‐C61‐butyric acid methyl ester (PCBM) ETL induced by NFAs modification significantly accelerates the electrons extraction. As a result, both Y6‐BO and Y7‐BO exhibit more effective interface modification effects compared to traditional PI molecules. The power conversion efficiency (PCE) of the inverted perovskite solar cell (i‐PSC) modified with Y7‐BO reaches 25.82 %. Moreover, the adoption of non‐polar solvents and the superior semiconductor properties of Y7‐BO molecules also enable perovskite solar modules (i‐PSM) with effective areas of 50 cm2, 400 cm2, and 1160 cm2 to achieve record efficiencies of 23.05 %, 22.32 %, and 21.1 % (certified PCE), respectively, making them the best PCE reported in the literature. Importantly, enhanced interface mechanical strength between the perovskite and PCBM layer results in significantly improved environmental and operational stability of the cells. The cells modified with Y7‐BO maintained 94.4 % of the initial efficiency after 1522 hours of maximum power point aging. [ABSTRACT FROM AUTHOR]

Abstract: We synthesized a series of compounds by changing the plasma atmosphere. Besides manganese nanoparticles using hydrogen and helium as the plasma atmosphere, sheet-like MnC8 and spherical Mn6N2.58 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. [Copyright &y& Elsevier]

Host‐guest complexation offers a promising approach for mitigating surface defects in perovskite solar cells (PSCs). Crown ethers are the most widely used macrocyclic hosts for complexing perovskite surfaces, yet their supramolecular interactions and functional implications require further understanding. Here we show that the dipole moment of crown ethers serves as an indicator of supramolecular interactions with both perovskites and precursor salts. A larger dipole moment, achieved through the substitution of heteroatoms, correlates with enhanced coordination with lead cations. Perovskite films incorporating aza‐crown ethers as additives exhibited improved morphology, reduced defect densities, and better energy‐level alignment compared to those using native crown ethers. We report power‐conversion efficiencies (PCEs) exceeding 25 % for PSCs, which show enhanced long‐term stability, and a record PCE of 21.5 % for host–guest complexation‐based perovskite solar modules with an active area of 14.0 cm2. [ABSTRACT FROM AUTHOR]

Electron‐withdrawing molecules (EWMs) have exhibited remarkable efficacy in boosting the performance of perovskite solar cells (PSCs). However, the underneath mechanisms governing their positive attributes remain inadequately understood. Herein, we conducted a comprehensive study on EWMs by comparing 2,2′‐(2,5‐cyclohexadiene‐1,4‐diylidene) bismalononitrile (TCNQ) and (2,3,5,6‐tetrafluoro‐2,5‐cyclohexadiene‐1,4‐diylidene) dimalononitrile (F4TCNQ) employed at the perovskite/hole transport layer (HTL) interfaces. Our findings reveal that EWMs simultaneously enhance chemical passivation, interface dipole effect, and chemically binding of the perovskite to the HTL. Notably, F4TCNQ, with its superior electron‐withdrawing properties, demonstrates a more pronounced impact. Consequently, PCSs modified with F4TCNQ achieved an impressive power conversion efficiency (PCE) of 25.21 %, while demonstrating excellent long‐term stability. Moreover, the PCE of a larger‐area perovskite module (14.0 cm2) based on F4TCNQ reached 21.41 %. This work illuminates the multifaceted mechanisms of EWMs at the interfaces in PSCs, delivering pivotal insights that pave the way for the sophisticated design and strategic application of EWMs, thereby propelling the advancement of perovskite photovoltaic technology. [ABSTRACT FROM AUTHOR]

Interface engineering is of great concern in photovoltaic devices. For the solution‐processed perovskite solar cells, the modification of the bottom surface of the perovskite layer is a challenge due to solvent incompatibility. Herein, a Cl‐containing tin‐based electron transport layer; SnOx‐Cl, is designed to realize an in situ, spontaneous ion‐exchange reaction at the interface of SnOx‐Cl/MAPbI3. The interfacial ion rearrangement not only effectively passivates the physical contact defects, but, at the same time, the diffusion of Cl ions in the perovskite film also causes longitudinal grain growth and further reduces the grain boundary density. As a result, an efficiency of 20.32% is achieved with an extremely high open‐circuit voltage of 1.19 V. This versatile design of the underlying carrier transport layer provides a new way to improve the performance of perovskite solar cells and other optoelectronic devices. [ABSTRACT FROM AUTHOR]

Organic–inorganic hybrid perovskites (OIHPs) are one of the hottest fields on account of their immense potential for photovoltaics. As one of the most promising OIHPs, formamidinium (FA)‐based perovskites have been developed very fast in the past few years. The power conversion efficiency (PCE) has reached certified 24.2%, which is comparable with that of monocrystalline silicon solar cells. However, the easy formation of nonperovskite δ‐phase formamidinium lead triiodide (FAPbI3) at a low temperature needs to be solved when fabricating a high‐quality light absorber layer. Several strategies have been used to avoid the formation of δ‐phase FAPbI3 and improve phase stability in recent years such as tolerance factor adjustment, dimensional engineering, addictive processing, interfacial modification, defects passivation, and in situ growth. These approaches can enhance the phase stability to some extent; however, their contribution to long‐term stability and especially their real mechanism is still unknown. Herein, the relationships among the tolerance factors, the structure of FAPbI3, and the phase transition phenomenon are summarized. In addition, various methodologies and potential mechanisms for stabilizing α‐phase FAPbI3 at room temperature (RT) are discussed. In conclusion, a series of challenges in the popular processings of perovskite solar cells and their corresponding solutions that help achieve commercialization faster are summarized. [ABSTRACT FROM AUTHOR]

Lead‐free perovskite solar cells (PSCs) are very much in demand for future high‐efficiency renewable electricity generation. In article number 1601130, Yuanyuan Zhou, Nitin P. Padture, Xiao Wei Sun, and co‐workers report efficient planar heterojunction‐depleted PSCs with power conversion efficiency up to 3.31% without the use of any additives, via modulation of phase‐pure B‐γ‐CsSnI3 grain coarsening. The delicate control of grain‐coarsening engineering plays a critical role in determining the morphology of photoactive layer, the exciton dynamical behaviors and thus the device performance. [ABSTRACT FROM AUTHOR]

Introducing fluorine (F) groups into a passivator plays an important role in enhancing the defect passivation effect for the perovskite film, which is usually attributed to the direct interaction of F and defect states. However, the interaction between electronegative F and electron‐rich passivation groups in the same molecule, which may influence the passivation effect, is ignored. We herein report that such interactions can vary the electron cloud distribution around the passivation groups and thus changing their coordination with defect sites. By comparing two fluorinated molecules, heptafluorobutylamine (HFBM) and heptafluorobutyric acid (HFBA), we find that the F/−NH2 interaction in HFBM is stronger than the F/−COOH one in HFBA, inducing weaker passivation ability of HFBM than HFBA. Accordingly, HFBA‐based perovskite solar cells (PSCs) provide an efficiency of 24.70 % with excellent long‐term stability. Moreover, the efficiency of a large‐area perovskite module (14.0 cm2) based on HFBA reaches 21.13 %. Our work offers an insight into understanding an unaware role of the F group in impacting the passivation effect for the perovskite film. [ABSTRACT FROM AUTHOR]

Phenyl‐C61‐butyric acid methyl ester (PCBM) remains the most commonly used electron transport layer in inverted perovskite solar cells (IPSCs). However, its insufficient electrical properties and passivation ability limit the device's performance. In this study, it is demonstrated that introducing an appropriate amount of n‐type polymer N2200 into the PCBM can simultaneously enhance the electrical properties of PCBM and passivate the defects distributed on perovskite surface. This modification of PCBM leads to improved band alignment and enhanced electron mobility. Simultaneously, N2200 polymer contains electron donors such as O, S involved in passivating uncoordinated Pb2+ defects. The PCBM@N2200‐based IPSCs exhibit an enhanced open‐circuit voltage (VOC) of 1.20 V with the minimum 0.36 V voltage loss and reach the champion power conversion efficiency (PCE) of 24.53% (certified PCE is 24.05%) with narrow distribution. Impressively, the corresponding module achieves an efficiency of 20.30% (11.19 cm2). Moreover, the PCBM@N2200‐based IPSCs maintain 96% of their initial efficiency after operating at the maximum power point for 500 h, thanks to the interfacial passivation, improved uniformity, and increased hydrophobicity resulting from N2200 doping. [ABSTRACT FROM AUTHOR]

High‐performance perovskite solar cells have demonstrated commercial viability, but still face the risk of contamination from lead leakage and long‐term stability problems caused by defects. Here, an organic small molecule (octafluoro‐1,6‐hexanediol diacrylate) is introduced into the perovskite film to form a polymer through in situ thermal crosslinking, of which the carbonyl group anchors the uncoordinated Pb2+ of perovskite and reduces the leakage of lead, along with the −CF2− hydrophobic group protecting the Pb2+ from water invasion. Additionally, the polymer passivates varieties of Pb‐related and I‐related defects through coordination and hydrogen bonding interactions, regulating the crystallization of perovskite film with reduced trap density, releasing lattice strain, and promoting carrier transport and extraction. The optimal efficiencies of polymer‐incorporated devices are 24.76 % (0.09 cm2) and 20.66 % (14 cm2). More importantly, the storage stability, thermal stability, and operational stability have been significantly improved. [ABSTRACT FROM AUTHOR]

Carbonyl functional materials as additives are extensively applied to reduce the defects density of the perovskite film. However, there is still a lack of comprehensive understanding for the effect of carbonyl additives to improve device performance. In this work, we systematically study the effect of carbonyl additive molecules on the passivation of defects in perovskite films. After a comprehensive investigation, the results confirm the importance of molecular dipole in amplifying the passivation effect of additive molecules. The additive with strong molecular dipole possesses the advantages of enhancing the efficiency and stability of perovskite solar cells (PSCs). After optimization, the companion efficiency of PSCs is 23.20 %, and it can maintain long‐term stability under harsh conditions. Additionally, a large‐area solar cell module‐modified DLBA was 20.18 % (14 cm2). This work provides an important reference for the selection and designing of efficient carbonyl additives. [ABSTRACT FROM AUTHOR]

The spontaneously formed uncoordinated Pb2+ defects usually make the perovskite films demonstrate strong n‐type with relatively lower carrier diffusion length and serious non‐radiative recombination energy loss. In this work, we adopt different polymerization strategies to construct three‐dimensional passivation frameworks in the perovskite layer. Thanks to the strong C≡N⋅⋅⋅Pb coordination bonding and the penetrating passivation structure, the defect state density is obviously reduced, accompanied by a significant increase in the carrier diffusion length. Additionally, the reduction of iodine vacancies also changed the Fermi level of the perovskite layer from strong n‐type to weak n‐type, which substantially promotes the energy level alignment and carrier injection efficiency. As a result, the optimized device achieved an efficiency exceeded 24 % (the certified efficiency is 24.16 %) with a high open‐circuit voltage of 1.194 V, and the corresponding module achieved an efficiency of 21.55 %. [ABSTRACT FROM AUTHOR]

The unavoidable iodine loss in the perovskite layer is closely related to carrier non‐radiative and device degradation. During the post‐annealing process, the fragile PbI bond is easy to break, leading to the formation of iodine vacancies and inducing stress‐driven structure collapse. Herein, a PbI6 octahedra stabilization strategy via building robust grain boundary modification networks is developed. The introduction of conjugated structure into amides can significantly enhance their anchoring ability with PbI units, while the π–π stacking effect of benzamide enables a passivation network with polymer‐like effect. This is well evidenced by the excellent properties in eliminated iodine loss and stabilized perovskite lattice. Therefore, benzamide modification not only transform the perovskite films from n‐type to p‐type by suppressing the iodine vacancy‐doping effect, but also reduces defect density, ultimately bringing the perovskite layer longer carrier diffusion length and better charge injection efficiency. Finally, the benzamide modified devices realize both high power conversion efficiency of 24.78% and excellent operating stability. Of particular note, the module efficiency with 14 cm2 active area is over 21%. [ABSTRACT FROM AUTHOR]

[Display omitted] • Different electron-drawing ability of end-group for guest materials were designed. • The IDTR had universality in multiple types of common host systems. • The PCE of PM6:IDTR:BTP-eC9 reached 19.54%. • The PM6:IDTR:L8-BO exhibited relatively strong photostability. Herein, we report two novel small-molecule (SM) guest materials with distinct end-groups, termed IDTO and IDTR, serving as a third component in organic solar cells (OSCs). We have employed time-resolved ultraviolet–visible (UV–vis) absorption during spin-coating, and unveiled distinct phases and transitions of the active layer by these SM guests during the film formation process. Incorporating SM guests is demonstrated to effectively mitigate energy losses, improve charge carrier mobility, and suppress recombination, collectively enhancing the open-circuit voltage (V OC), short-circuit current (J SC), and fill factor (FF). We have firmly established that the incorporation of SM guests elevates film crystallinity, refines nanoscale phase distribution, and modulates vertical phase distribution. This collective optimization catalyzes a remarkable enhancement in device performance. Notably, the champion ternary OSCs, including PM6:IDTR:L8-BO and PM6:IDTR:BTP-eC9, achieved power conversion efficiencies (PCE) of 19.12% and 19.54%, respectively, marking some of the highest values reported to date in their respective systems. Moreover, IDTR-based ternary OSCs have exhibited remarkable photostability. This excellent universality and stability emphasizes the importance of end-groups manipulation of the third component and provides new ideas for molecular design. [ABSTRACT FROM AUTHOR]

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 Pb2+ and anchor the I‐ of the [PbI6]4− octahedron. Additionally, the interfacial PMMA‐AM passivation layer cannot be destroyed during the hole transport layer deposition because of its low solubility in chlorobenzene. This passivation leads to an enhancement in the open‐circuit voltage from 1.12 to 1.22 V and improved stability in solar cell devices, with the device maintaining 95 % of the initial power conversion efficiency (PCE) over 1000 h of maximum power point tracking. Additionally, a large‐area solar cell module was fabricated using this approach, achieving a PCE of 20.64 %. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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‐Pb2+ interactions with under‐coordinated Pb2+ in perovskite. This π‐Pb2+ 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‐Pb2+ 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 high 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. [ABSTRACT FROM AUTHOR]

Given that thermal stability is of considerable importance in the field of photovoltaics, inorganic perovskites have attracted numerous attempts to overcome instability caused by volatile cations in organic–inorganic hybrid perovskites. As always, crystallization optimization is a paramount strategy to enhance the performance of inorganic perovskite‐based solar cells. Recently, nanoconfined crystallization is regarded as a novel and effective strategy due to the absence of chemical reactions. Herein, 1D ordered mesoporous silica is introduced into inorganic perovskite precursors to facilely induce the nanoconfined crystallization. Both theoretical and experimental analyses verify that the nanoconfined crystallization is successfully triggered by the ordered mesoporous silica, fostering the formation of 1D perovskite monocrystal. In addition, the crystallization and morphology of inorganic perovskite are effectively facilitated. As a result, the nonradiative recombination is suppressed along with the distinctly reduced trap‐state density and remarkably enhanced charge transport in perovskite. Finally, the power conversion efficiencies of CsPbIBr2‐ and CsPbI3‐based solar cells are boosted from 8.67% to 10.04% and from 14.10% to 14.69%, respectively. Meanwhile, stability tests of solar cells also show enhancement using the nanoconfined crystallization. This work provides a facile, effective, and flexible crystallization modulating strategy for fabricating efficient and stable inorganic perovskite solar cells. [ABSTRACT FROM AUTHOR]

Inorganic CsPbI3 perovskite with an optical bandgap ranging from 1.67 to 1.75 eV is a promising light‐harvesting material as a top cell in tandem solar cells, but its high fabrication temperature can damage the middle layers or the bottom subcells. Here, an additive‐involved leaching method to fabricate CsPbI3 perovskite films is demonstrated, which can decrease the preparation temperature to 100 °C. The CsPbI3 perovskite films with high crystallinity are achieved by a solution assisted reaction between DMAPbI3 and Cs4PbI6 with the leaching of DMA+, Cs+, and I−. The as‐prepared CsPbI3 perovskite films exhibit much superior stability compared to their high‐temperature counterparts. As a result, a power conversion efficiency of over 16% is obtained, and the unencapsulated device maintains over 93% of the initial efficiency after aging for 30 days in air with a relative humidity of 10%. [ABSTRACT FROM AUTHOR]

Organic ionic plastic crystals (OIPCs) are synthesized through a simple metal‐free, cost‐effective approach. The strategized synchronization of electron‐rich phenoxazine with benzimidazolium iodide (OIPC‐I) and bromide (OIPC‐Br) salts lead to enhanced hole mobility and conductivity of OIPCs which is suitable for an efficient alternative to conventional organic hole transporting materials (HTMs) for stable perovskite solar cells (PSCs). The fabricated PSCs with OIPC‐I as hole transporting layer yielded a power conversion efficiency of 15.0% and 18.1% without and with additive (Li salt) respectively, which are comparable with spiro‐OMeTAD based devices prepared under similar conditions. Furthermore, the PSCs with OIPCs show good stability compared to the spiro‐OMeTAD with or without additives. Here, first time benzimidazolium‐based OIPCs have been used as an alternative organic HTM for perovskite solar cells, which opens a window for the design of effective OIPCs for highly efficient PSCs with long‐term stability. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

[Display omitted] • An In element-buried CZITSSe/CZTSSe homojunction absorber is reconstructed. • The CZITSSe/CZTSSe homojunction generates shallow-level In Zn donors. • The In Zn donors suppress defect clusters and enlarge the surface band bending. • Achieve an active-area efficiency of 13.59 % with a high V oc of 0.527 V. The Cu 2 ZnSn(S,Se) 4 solar cells (CZTSSe) are emerging as a hot area of low-cost thin film photovoltaic technology owing to its non-toxicity and excellent photoelectric properties. However, the large open-circuit voltage deficit (V oc,deficit) caused by the inherently defective CdS/ CZTSSe heterojunction interface is still a huge challenge for improving power conversion efficiency. Herein, we reconstruct the heterojunction interface by inserting a CZTSSe:In into the CdS/CZTSSe heterojunction through an In 2 Se 3 post-deposition treatment. The local occupation of In3+ at Zn2+ and Sn4+ sites decreases the disordered Zn- and Sn-related deep defects and generates benign In Zn donors within CZITSSe transition layer simultaneously, which effectively enhances the surface p-to-n conversion. The combination of chemical and field-effect passivation regulates the charge extraction and passivates the charge recombination. As a result, the In element-buried absorber enables the V oc boost from 488 to 527 mV with an impressive active-area efficiency of 13.59 %. These results demonstrate the great potential of the In element-buried absorber in alleviating the V oc,deficit and enhancing the performance of CZTSSe solar cells. [ABSTRACT FROM AUTHOR]

Graphene-wrapped iron carbide nanoparticles (Fe 3 C@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 Fe 3 C@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 Fe 3 C@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. [ABSTRACT FROM AUTHOR]

Measles remain to be an important global public health issue in China. In spite of large coverage rates of the first dose of Measles mumps rubella (MMR) combination vaccines (MMR1), large numbers of measles cases continue to be reported in China in recent years due to the high incidence and the low coverage of the second MMR vaccine dose (MMR2). This paper is devoted to modeling the combined effects of MMR1 and MMR2 coverage rates on the controlling of measles. To do that, we propose and study a robust time-delayed compartment measles infection model where MMR2 is followed after a fixed time interval of MMR1, and the combined elements of infection and mass immunization are also considered. By using the methods of Lyapunov functional and the uniform theory for infinite-dimensional dynamical systems, a threshold dynamics determined by the basic reproduction number $\Re_{0}$ is established: the measles can be eradicated if $\Re_{0}<1$ , whereas the disease persists if $\Re_{0}>1$ . Moreover, it is shown that the endemic equilibrium is locally asymptotically stable once $\Re_{0}>1$ . Numerical simulations are performed to support the theoretical results and to consider the effects of MMR2 on the controlling of measles. Our results show that to eliminate measles in China, we should have MMR1 coverage rates larger than 88.01% based on perfect MMR2 coverage, and have MMR2 coverage rates larger than 92.63% based on perfect MMR1 coverage; Moreover, our simulations suggest that there is a risk that paradox of vaccination against measles in China may occur: that is, the final size of infected individuals may even increase in spite of the increase of MMR2 coverage rates. [ABSTRACT FROM AUTHOR]

[Display omitted] • The adverse effects caused by defects and secondary phases in kesterite CZTSSe thin-film solar cells are elucidated. • Strategies and recent advances to improve CZTSSe device performance through defect suppression are summarized. • Suggestions and prospects for developing high-efficiency CZTSSe solar cells are presented. Comprising of earth-abundant, inexpensive, and environmentally friendly elements, kesterite Cu 2 ZnSn(S,Se) 4 (CZTSSe) solar cells are demonstrated to have enormous potential to be an excellent alternative to the commercial Cu(In,Ga)(S,Se) 2 (CIGSSe) and CdTe thin-film solar cells. However, the record power conversion efficiency (PCE) of CZTSSe is only 13.0%, which lags far behind state-of-the-art commercial thin-film solar cells (22%–23%). A wide variety of carrier recombination centers, including defects, defect clusters, and secondary phases, which cause nonradiative recombination of carriers and photovoltage loss of the CZTSSe device, is assumed to be the main arch-criminal for poor efficiency. This review focuses on frontier modification strategies to suppress charge recombination. The adverse effects caused by defects and secondary phases in kesterite CZTSSe thin-film solar cells are elucidated. Meanwhile, the recent advances in kesterite CZTSSe solar cells are summarized from extrinsic cation doping, interface engineering, and removal of secondary phases. Finally, the principles of improving the efficiency of CZTSSe are clarified. [ABSTRACT FROM AUTHOR]

A bio-based hybrid film containing chitosan (CS) and silver nanowires (AgNWs) has been prepared by a simple casting technique. X-ray diffraction (XRD), Fourier infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and UV–visible spectroscopy were employed to characterize the structure of bio-based film. The bio-based hybrid film showed unique performance compared with bare chitosan film. The incorporated nano-silver could improve the strength properly. The results revealed that AgNWs in CS film, improved its tensile strength more than 62% and Young modulus 55% compared with pure chitosan film. On the other hand tensile strength was increased 36.7% with AgNPs. Importantly, the film also exhibited conductivity and antibacterial properties, which may expand its future application. [ABSTRACT FROM AUTHOR]

[Display omitted] • A nearly ideal I/Pb ratio (2.94) was obtained for the MAM-treated film, which eliminated the iodine-poor condition. • A high efficiency of 24.13% was obtained with MAM-treating, while the control device was only 20.88%. • The modified device kept 96% of its initial PCE after over 900 h MPP tracking. The iodine loss in the perovskite layer is currently-one of the major limit for further boosting power conversion efficiency (PCE) and long-term stability of perovskite solar cells (PSCs). Iodine-poor interface dominates the generation of some deep level defects and the phase collapse in the perovskite layer. So how to adequately immobilize the iodine and passivate the existing undercoordinated lead cations is a critical challenge. Herein, the interaction between the bifunctional amide group and the perovskite layer was systematically investigated. The Malonamide (MAM) with bis(amide) group in structure can selectively hold iodine in place or interact with undercoordinated lead cations through adjusting the molecular conformation, resulting in more ideal I/Pb ratio, highly suppressed ion migration, harmonized surface potential and reduced defect density. Eventually, a significantly improved efficiency of 24.13% was demonstrated with the MAM-treating devices, and the device kept 96% of its initial efficiency after 900 h under continuous illumination. [ABSTRACT FROM AUTHOR]