Enlarged Grain Research Articles

Preparation and study of polydimethylsiloxane/polytetrahydrofuran blended soft‐segment‐based passive cooling polyurethane materials

AbstractThis study introduces a series of novel passive‐cooling polyurethane materials (SiTPUs) by incorporating hydroxybutane‐terminated polydimethylsiloxane (OH‐PDMS)/polytetrahydrofuran (PTMG)‐mixed soft segments. Wide‐angle x‐ray scattering (WAXS) and small‐angle x‐ray scattering (SAXS) analyses revealed that with an increase in the OH‐PDMS content, the material exhibited enlarged grain sizes, reduced crystallinity, and the formation of larger‐sized microphase “structures with different compatibilities. The sample with a PDMS proportion of 40% (SiTPU‐40) demonstrates outstanding passive cooling performance, achieving a reflectance of 70.2% in the solar spectrum and a high atmospheric window emissivity of 91.6% without needing metal additives, resulting in a cooling effect of 10.8°C compared with that of pure thermoplastic polyurethane (TPU). Static contact angle tests indicated that introducing OH‐PDMS considerably enhanced the self‐cleaning performance of the material, with a PDMS proportion of 50% (SiTPU‐50) achieving the highest contact angle of 112°. Overall, this multi‐soft segment design optimizes passive cooling performance and enhances self‐cleaning capabilities, thus offering new possibilities for extensive material applications, especially in wearable technology and architectural surface coatings.

Low dielectric loss and high temperature stability of tri-rutile NiO–SnO2–Ta2O5 ceramics simultaneously achieved by component optimization design

The structural analysis and microwave dielectric characteristics of ionic-modified tri-rutile Ni0·5Sn0·5TaO4 ceramics, focusing on ionic non-stoichiometry and substitution strategies, were systemically studied in this work. A tri-rutile solid solution was unequivocally identified via X-ray diffraction, Raman scatting spectra analysis, and transmission electron microscopy characterization under [110] direction. The unit cell of the tri-rutile structure experiences a contraction primarily due to the compression of the [M2O6] octahedron. An excess of Ni content and the incorporation of (Al1/2Nb1/2)4+ complex cations notably halved the grain size. Conversely, deliberate Sn deficiency led to enlarged grain sizes; however, grain boundaries blurred when the deficiency exceeded 0.03 mol. The microwave dielectric properties are intricately linked to structural characteristics and sintering behavior. Ionic polarizabilities and bulk density predominantly affect the εr value, while grain growth governs variations in the Q × f value. The distortion of [M2O6] octahedra primarily influences the τf value. All measured τf values demonstrated exceptional temperature stability within the range of -5 ∼ +5 ppm/°C. Notably, the Ni0·5Sn0·47TaO4 ceramic displayed outstanding microwave dielectric characteristics: εr = 21.9, Q × f = 45,055 GHz (at f = 10.7 GHz), and τf = -2.07 ppm/°C post-sintering at 1425 °C, rendering it ideal for applications in extreme environmental conditions.

Effect of Ni element on microstructure and properties of cold-rolled 316 L austenitic stainless steel

In this current investigation, the impact of Nickel (Ni) on the microstructural attributes and properties of a cold-rolled 316 L sheet was examined. The microstructure and phase configuration of austenitic stainless steels, specifically 316 L and 316LNi, were meticulously characterized through the utilization of metallography, X-ray Diffraction (XRD), and Electron Backscatter Diffraction (EBSD) techniques. Subsequent assessments were conducted to evaluate magnetic characteristics, microhardness, and tensile properties. The phase structure of both austenitic stainless steels conforms to a Face-Centered Cubic (FCC) crystal lattice, whereby the grain content oriented along the (110) plane progressively escalates with augmenting degrees of cold rolling. The magnetic conductivity of these austenitic stainless steels satisfactorily adheres to established standards. The incorporation of Nickel (Ni) into the alloy composition enhances the cold deformation capacity of 316 L stainless steel. However, substantial plastic deformation yields heightened dislocation density, thereby promoting enlarged grain dimensions upon solution treatment. Throughout subsequent cold rolling deformation sequences, the augmented grain size observed in 316LNi stainless steel leads to a reduction in dislocation density within the equivalently ordered cold-rolled plate. Simultaneously, this augmented grain size engenders a decline in grain boundary content coupled with an augmentation in twin content. Consequently, the interplay of grain coarsening, diminished dislocation density, and twin-induced softening collectively bestows upon 316LNi stainless steel a lower tensile strength compared to 316 L stainless steel, albeit accompanied by heightened plasticity.

Forming enlarged grain and fixed boundary via a two-step surface modification to achieve stable inverted perovskite solar cells

Having a stable interface between perovskite and electron transport layer at p-i-n hybrid halide perovskite solar cells (PSCs), has been considered to be crucial to improve the performance of device. Here, a two-step sulfur-containing molecules surface treatment procedure (TST) was utilized, which involves sequentially coating 2-thiazolamide hydrochloride (SFACl) and methylamine sulfate (MA2SO4) onto the surface of perovskite film to achieve solid interface. Consequently, SFACl induced grains enlarged following a dissolution-crystallization model and formed 2D/3D heterojunction (n = 1); MA2SO4 and residual PbI2 reacted to form PbSO4, which priorly appeared at the grain boundaries. Owing to the interaction between sulfur-containing molecules and perovskite/PbI2, TST film showed improved photoluminescence intensity and prolonged lifetimes. Importantly, TST solar cell (Target 2) achieved a champion efficiency of 21.94 % for CsFA-based device (23.19 % for CsFAMA-based device, certified 23.02 %) compared with that of 20.05 % (Control). The improved device performance was primarily attributed to the larger grain size and defects passivation via multifunctional sulfur-containing molecules. Operational stability results shown that Target 2 device remained 78 % of the initial efficiency while Control remained 57 % of that under continuous illumination after 700 hrs in N2 at room temperature, which can be ascribed to the stable interface inhibiting ion migration. This study offers a comprehensive understanding of sulfur-containing molecules surface modification in PSCs.

Zma-miR159 targets ZmMYB74 and ZmMYB138 transcription factors to regulate grain size and weight in maize.

Endosperm cell number is critical in determining grain size in maize (Zea mays). Here, zma-miR159 overexpression led to enlarged grains in independent transgenic lines, suggesting that zma-miR159 contributes positively to maize grain size. Targeting of ZmMYB74 and ZmMYB138 transcription factor genes by zma-miR159 was validated using 5' RACE and dual-luciferase assay. Lines in which ZmMYB74 was knocked out using clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9) presented a similar enlarged grain phenotype as those with zma-miR159 overexpression. Downstream genes regulating cell division were identified through DNA affinity purification sequencing using ZmMYB74 and ZmMYB138. Our results suggest that zma-miR159-ZmMYB modules act as an endosperm development hub, participating in the division and proliferation of endosperm cells.

Highly efficient and stable quasi two-dimensional perovskite solar cells via synergistic effect of dual additives

Recently, quasi two-dimensional (Q-2D) perovskites with alternating cations in the interlayer space (ACI) have attracted more attentions owing to their elevated stability compared with three-dimensional (3D) analogs. While the efficiency of the devices derived from Q-2D perovskites is much smaller than that based on 3D perovskites. Here, we utilized urea and methoxyamine hydrochloride (MOAH) dual additives to acquire high quality Q-2D ACI perovskite GA(MA)5Pb5I16 (GA = guanidinium, MA = methylammonium) films. The efficiency of the perovskite solar cells (PSCs) derived from the Q-2D perovskite films induced by the synergistic effect of urea and MOAH dual additives increases to 20.32% from 17.21% for the devices without additive. This efficiency enhancement could be attributed to the enlarged grain size, improved crystallinity, optimized quantum well thickness distribution, and reduced trap states of the perovskite films. Moreover, the solar cells with dual additives present improved stability. The efficiency of devices with dual additives holds 95% of the original value after storage for 1600 h in ambient air. These results prove that the synergistic effect of urea and MOAH is an effective method to achieve highly efficient and stable Q-2D PSCs.

Fully Methylammonium-Free Stable Formamidinium Lead Iodide Perovskite Solar Cells Processed under Humid Air Conditions.

Fabricating perovskite solar cells (PSCs) in ambient air condition is beneficial for lowering the processing cost and boosting the commercialization. Formamidinium lead iodide (FAPbI3) is an attractive candidate for efficient PSCs; however, it easily suffers from degradation and phase transition in the presence of ambient moisture. Methylammonium (MA) cation is commonly incorporated to stabilize FAPbI3, whereas the residual MA tends to deteriorate the thermal and operational stability. Herein, we report a MA-free strategy to fabricate high-quality α-FAPbI3 films and inverted PSCs under open air conditions with a relative humidity (RH) of 60 ± 10%. The incorporation of phenylethylammonium iodide (PEAI) effectively inhibits the decomposition and phase transition of FAPbI3 during its crystallization in humid air. Accordingly, phase-pure α-FAPbI3 perovskite films with significantly reduced δ-FAPbI3 and PbI2 content are successfully obtained. In addition, introducing PEAI strongly enhances the crystallinity of FAPbI3 perovskite films, thereby yielding enlarged grain sizes and reduced grain boundaries. Defects at the grain boundaries and surface are further passivated by PEAI addition, so that the trap state density is significantly decreased. As a result, the non-radiative recombination is effectively suppressed and the charge carrier transport is promoted. The inverted device optimized with a suitable PEAI concentration exhibits an enhanced power conversion efficiency (PCE) of 17.83%, which significantly surpasses the control device (12.29% PCE). Moreover, the PEAI optimized FAPbI3 PSCs demonstrate strongly improved long-term stability, with nearly 97% PCE maintained after 27-day storage under ambient conditions. This work provides a feasible way to fabricate PSCs in ambient air for promoting their wide range of applications.

In situ crosslinking-assisted perovskite grain growth for mechanically robust flexible perovskite solar cells with 23.4% efficiency

•Enhanced the crystallization of flexible perovskite •Reduced Young’s modulus of perovskite film •Exhibited record efficiency •Exhibited excellent mechanical stability Flexible perovskite solar cells (pero-SCs) are the best candidates to complement silicon solar cells in the photovoltaic market. However, their power conversion efficiencies (PCEs) and mechanical stability are far behind the industry standards because of the uncontrollable growth of perovskites on plastic substrates and intrinsically high Young’s modulus. We explored an in situ crosslinking bis((3-methyloxetan-3-yl) methyl) thiophene-2,5-dicarboxylate along with perovskite growth, and its coordination ability and crosslinking temperature enabled the fine regulation of the quality of perovskite in real time. The resultant perovskite film exhibits an enlarged grain size, compact stacking, and a preferential crystal orientation. Moreover, the crosslinked elastomer polymer gathered at the perovskite grain boundaries can effectively release the mechanical stress. As a result, the flexible pero-SC based on this perovskite film achieved a record PCE of 23.4% (certified 22.9%), which is comparable with that of the rigid device. Importantly, the flexible pero-SCs also display a robust bending durability. Flexible perovskite solar cells (pero-SCs) are the best candidates to complement silicon solar cells in the photovoltaic market. However, their power conversion efficiencies (PCEs) and mechanical stability are far behind the industry standards because of the uncontrollable growth of perovskites on plastic substrates and intrinsically high Young’s modulus. We explored an in situ crosslinking bis((3-methyloxetan-3-yl) methyl) thiophene-2,5-dicarboxylate along with perovskite growth, and its coordination ability and crosslinking temperature enabled the fine regulation of the quality of perovskite in real time. The resultant perovskite film exhibits an enlarged grain size, compact stacking, and a preferential crystal orientation. Moreover, the crosslinked elastomer polymer gathered at the perovskite grain boundaries can effectively release the mechanical stress. As a result, the flexible pero-SC based on this perovskite film achieved a record PCE of 23.4% (certified 22.9%), which is comparable with that of the rigid device. Importantly, the flexible pero-SCs also display a robust bending durability.

Spatial Control of the Hole Accumulation Zone for Hole-Dominated Perovskite Light-Emitting Diodes by Inserting a CsAc Layer.

Perovskites show efficient electroluminescence and are expected to have wide applications in light-emitting diodes (LEDs). However, owing to the unbalanced electron-hole transport properties of some highly luminescent perovskites, a fundamental challenge is that the exciton recombination zone of perovskite LEDs (PeLEDs) typically overlaps with an accumulation of the major carrier. It is known to reduce the performances of PeLEDs, leading to a reduction of efficiency and operation stability due to Auger recombination. To address this issue in a hole-dominated blue PeLED, we propose to insert a cesium acetate (CsAc) layer between the hole transport layer (HTL) and the hole-dominant perovskite layer. Electronic properties indicate that the hole accumulation zone of the device with the CsAc layer shifts away from the perovskite/ETL interface, i.e., the recombination zone, to the HTL/CsAc interface. Separation of the hole accumulation region and the exciton recombination zones substantially suppresses exciton quenching. Moreover, the CsAc layer can also improve the photophysical properties of the perovskite film by providing an extra Cs source to interact with the defect site of unreacted PbBr2 in the perovskite film and enhance the crystallinity of the perovskite with an enlarged crystal grain size. As a result, the external quantum efficiency (EQE) of the sky-blue PeLEDs shows considerable improvement from 5.3 to 9.2% upon inserting the CsAc layer.

A Self‐Assembled Vertical‐Gradient and Well‐Dispersed MXene Structure for Flexible Large‐Area Perovskite Modules

AbstractAdvancing hole transport layers (HTL) to realize large‐area, flexible, and high‐performance perovskite solar cells (PSCs) is one of the most challenging issues for its commercialization. Here, a self‐assembled gradient Ti3C2Tx MXene incorporated PEDOT:PSS HTL is demonstrated to achieve high‐performance large‐area PSCs by establishing half‐caramelization‐based glucose‐induced MXene redistribution. Through this process, the Ti3C2Tx MXene nanosheets are spontaneously dispersed and redistributed at the top region of HTL to form the unique gradient distribution structure composed of MXene:Glucose:PEDOT:PSS (MG‐PEDOT). These results show that the MG‐PEDOT HTL not only offers favorable energy level alignment and efficient charge extraction, but also improves the film quality of perovskite layer featuring enlarged grain size, lower trap density, and longer carrier lifetime. Consequently, the power conversion efficiency (PCE) of the flexible device based on MG‐PEDOT HTL is increased by 36% compared to that of pristine PEDOT:PSS HTL. Meanwhile, the flexible perovskite solar minimodule (15 cm2 area) using MG‐PEDOT HTL achieve a PCE of 17.06%. The encapsulated modules show remarkable long‐term storage stability at 85 °C in ambient air (≈90% efficiency retention after 1200 h) and enhanced operational lifetime (≈90% efficiency retention after 200 h). This new approach shows a promising future of the self‐assembled HTLs for developing optoelectronic devices.

Gw2.1, a new allele of GW2, improves grain weight and grain yield in rice

Grain weight is an important characteristic of grain shape and a key contributing factor to the grain yield in rice. Here, we report that gw2.1, a new allele of the Grain Width and Weight 2 (GW2) gene, regulates grain size and grain weight. A single nucleotide substitution in the coding sequence (CDS) of gw2.1 resulted in the change of glutamate to lysine (E128K) in GW2.1 protein. Complementation tests and GW2 overexpression experiments demonstrated that the missense mutation in gw2.1 was responsible for the phenotype of enlarged grain size in the mutant line jf42. The large grain trait of the near-isogenic line NIL-gw2.1 was found to result from increased cell proliferation during flower development. Meanwhile, NIL-gw2.1 was shown to increase grain yield without compromising the grain quality. The GW2 protein was localized to the cell nucleus and membrane, and interacted with CHB705, a subunit of the chromatin remodeling complex. Finally, the F1 hybrids from crosses of NIL-gw2.1 with 7 cytoplasmic male-sterile lines exhibited large grains and desirable grain appearance. Thus, gw2.1 is a promising allele that could be applied to improve grain yield and grain appearance in rice. Availability of data and materialsThe datasets generated and/or analyzed in the study are available from the corresponding author on reasonable request.

Grain size enlargement and controlled crystal growth by formamidinium chloride additive-added γ-CsPbI2Br thin films for stable inorganic perovskite solar cells

Replacing the organic cation with inorganic cation in cesium-based perovskite has fascinated more consideration in halide perovskite solar cells (PSCs) because of their inherent stability and power conversion efficiency (PCE). In the present study, we proposed a new method to increase the stability and PCE of γ-CsPbI2Br-based inorganic perovskite solar cells by adding the formamidinium chloride (FACl) additive into the γ-CsPbI2Br perovskite precursor solution. The FACl additive shows a significant role in the γ-CsPbI2Br perovskite phase to modify the morphology and particular crystal growth to make high-quality perovskite thin films. Also, the FACl additive retards crystallization kinetics to yield a highly crystalline γ-CsPbI2Br perovskite phase, comprising enlarged grain size with reduced charge recombination. The optimum amount of FACl (3 mg/ml) additive-added γ-CsPbI2Br-based device demonstrated a PCE of 15.03%, which is higher than that of the bare γ-CsPbI2Br-based device (12.97%). The stability analysis of the FACl additive-based devices showed high thermal stability that maintains 86% of its initial PCE at 250 h in ambient conditions at 85 °C thermal stress.

Defects passivation via d-glucosamine hydrochloride for highly efficient and stable perovskite solar cells

The defects existing on surface and grain boundaries in organic-inorganic halide perovskite films are detrimental to both the performance and stability of perovskite solar cells (PVSCs). Here, an additive of Glucosamine hydrochloride (D-GH) is introduced into the perovskite precursor solution to achieve high power conversion efficiency (PCE) and long-term stability. It is found that D-GH additive can significantly improve of the quality of perovskite film with enhanced crystallinity, compact and smooth surface and slightly enlarged grain size, leading to reduced grain boundaries, trap densities and thus negligible hysteresis in the resultant PVSCs. The optimized devices with 0.05 mg/ml D-GH additive show the best device performance with an enhanced PCE of 20.30%, as compared to the control devices with the highest PCE of 17.77%. In addition, the stability of PVSCs with 0.05 mg/ml D-GH modification is much better than that of the reference one. Overall, this work demonstrates a green and cheap additive to fabricate highly efficient and stable PVSCs. • Glucosamine hydrochloride (D-GH) was introduced into perovskite precursor solution to improve the performance of PVSCs. • The D-GH additive can significantly improve the quality of perovskite film and reduced trap densities. •. The device with D-GH as additive shows enhanced performance with PCE of 20.30%. •The stability of PVSCs with D-GH modification is much better than that of the reference one.

Additive-Induced Film Morphology Evolution for Inverted Dion–Jacobson Quasi-Two-Dimensional Perovskite Solar Cells with Enhanced Performance

In the past decade, three-dimensional (3D) perovskites have been under intense study. However, these devices always suffer from severe performance degradation. Recently, two-dimensional (2D) perovskites have attracted increasing attention due to their excellent environmental stability, but their low power conversion efficiency (PCE) limits their application. Therefore, many strategies have been applied to manipulate the crystallization and suppress the defects and low-n value phases. Additive engineering, as one of the most effective methods to achieve the above-mentioned goals, has been extensively studied. In this contribution, thiourea (TU) and methylammonium chloride (MACl) are successfully employed to contribute synergistically to optimize the crystallization process, leading to an enlarged grain size, smooth and dense surface morphology, and suppressed distribution of n values for improved phase purity. As a result, the optimized inverted Dion–Jacobson (DJ) 2D perovskite solar cell (PSC) device delivers an elevated PCE of 12.16% with a significantly improved short-circuit current density (JSC) of 18.78 mA cm–2 and fill factor (FF) of 62.70%. In addition, the optimized devices show good environmental stability when exposed to ambient air.

Passivation of perovskite surfaces using 2-hydroxyacetophenone to fabricate solar cells with over 20.7% efficiency under air environment

As known, some defect states of perovskite film still seriously affect the efficiency and stability of perovskite solar cells (PSCs), and different passivation approaches have different passivation principles, areas, degrees and additional effects on perovskite films. Herein, in this contribution, we design a three-step optimization method including interface optimization and additive passivation strategies for enhancing the quality of perovskite films all-round, thereby increasing the power conversion efficiency (PCE) as well as enduring stability of PSCs which fabricated in atmospheric environment. We employ the L-aspartic acid (L-Asp) buffer layer which rich in amino acids, the cross-linking Sodium Glycinate (SG) additive with carboxylate and small amount of 2-Hydroxyacetophenone (2-HA) containing carbonyl groups to modify the bottom, inner and top parts of perovskite films, respectively. As a result, the passivated internal and surface defects of perovskite film could achieve an enlarged average grain size (500 nm) and display more defect-less, dense morphology. The strengthened interfacial charge transport ability can significantly improve the photovoltaic performance of devices. Consequently, the optimized PSC bring about the negligible hysteresis of photocurrent and a dramatic 20.71% PCE. Moreover, the temperature and moisture stability of optimized PSCs are both remarkably enhanced. The normalized PCE of un-encapsulated device which modified via 2-HA could still retain 80% of its original value after placed in the dark for 100 hours at 50% relative humidity and 85 °C, simultaneously. Overall, this simple and practical strategy supplies a hopeful channel to facilitate the commercialized PSCs.

Structure and mechanical properties of welded joints of high-strength low-alloy steel for arctic purposes

The work is devoted to the research of cracks causes in welded joints of high­strength steel for arctic purposes based on the study of the structure and mechanical properties of the weld metal and the zone of thermal influence. Consumers of machine­building products make increasingly high demands on welded joints of metal structures. This necessitates the use of rolled steels for their production, which have increased mechanical and special properties. When welding MAGSTRONG W700 type steels, cracks are observed in local sections of welded joints. It was established that the structure of the weld metal of welded joints of MAGSTRONG W700 steel is characterized by the presence of columnar crystals with a hardness of 312 – 323 HV. The metal structure in the overheating area of thermal influence zone is characterized by the presence of enlarged primary grain, as well as batch formations of bainite and bainite-martensite with hardness of 338 – 352 HV. The level of temporary resistance to rupture of the metal in thermal influence zone is 618 – 627 MPa. Depending on the test temperature, values of the impact strength of the metal in thermal influence zone vary from 62 to 86 J/cm2. MAGSTRONG W700 steel has good resistance to the formation of hot cracks during welding (UCS = 20,3), however, it has an increased tendency to form cold cracks (CE = 0,48). Analysis of the data obtained showed that destruction of welded joints of the studied steel occurs due to its unsatisfactory weldability. Such weldability is due to a complex chemical composition, as well as a whole set of factors (such as the formation of unfavorable structures in the metal of welded joints under the influence of thermal welding cycles, a complex picture of welding stresses, the level of which exceeds the temporary resistance to metal rupture). Also, the structure of the weld metal has a large­crystalline structure, which significantly weakens the connection.

Enhanced magnetic properties of strontium ferrites through constructing magnetoelastic stress

Strontium ferrites, which exhibit large remanence, high coercivity (Hc), are fascinating for applications in motors and high-frequency microwave devices. Here we demonstrate the strontium ferrites (Sr0.34Ca0.25La0.41Fe11.4Co0.19O19-δ) sintered at 1150 °C with enhanced magnetic properties through constructing magnetoelastic stress. The effects of applied pressure (Pc-axis) of 0–16 kPa during the sintering process on phase compositions, morphologies, magnetic and microwave properties are investigated in detail. We note that the Pc-axis could contribute to enhanced c-axis preferred orientation. This mechanism of enhancement has been also discussed according to the magnetoelastic theory. By applying an external pressure of 8 kPa, intrinsic coercivity (Hcj) of 4657 Oe and magnetic coercivity (Hcb) of 3781 Oe are obtained. The increments are 8.1% and 18.0% for Hcj and Hcb, respectively, compared to the sample with Pc-axis of 0 kPa. However, the enhancement of Hc by the Pc-axis is seen to be limited above 8 kPa, which can be attributed to the enlarged grain size and porosity observed. In addition, the ferromagnetic resonance frequency (fr) is also increased by the increased Pc-axis.

Enhanced Photovoltaic Performance via a Bifunctional Additive in Tin-Based Perovskite Solar Cells

Tin-based perovskites with low toxicity and a narrow band gap have been promising candidates for the fabrication of efficient lead-free perovskite solar cells (PSCs). Nevertheless, the power conversion efficiency (PCE) of tin-based PSCs still lags behind that of their lead counterparts due to the poor film quality induced by uncontrollable crystal growth and Sn2+ self-doping. Herein, we introduce a bifunctional additive, ammonium thiocyanate (NH4SCN), into the precursor solution, which is able to coordinate with SnI2 to effectively control the crystal growth of the FASnI3 perovskite and further passivate the trap states in the perovskite films. Furthermore, the modified FASnI3 perovskite displays an improved film quality, featuring a compact surface morphology with an enlarged grain size, as well as decreased trap density, resulting in the reduction of the Sn4+/Sn2+ proportion in the film. As a result, a considerably enhanced PCE from 4.45 to 8.15% has been demonstrated. More importantly, the NH4SCN-based device exhibits advanced environment stability, retaining over 70% of the initial efficiency after 100 h of exposure to 35 ± 5% relative humidity at room temperature in a dark environment. This finding provides an additive strategy to improve the efficiency and stability of tin-based PSCs.

Separable regulation of POW1 in grain size and leaf angle development in rice.

SummaryLeaf angle is one of the key factors that determines rice plant architecture. However, the improvement of leaf angle erectness is often accompanied by unfavourable changes in other traits, especially grain size reduction. In this study, we identified the pow1 ( put on weight 1 ) mutant that leads to increased grain size and leaf angle, typical brassinosteroid (BR)‐related phenotypes caused by excessive cell proliferation and cell expansion. We show that modulation of the BR biosynthesis genes OsDWARF4 (D4) and D11 and the BR signalling gene D61 could rescue the phenotype of leaf angle but not grain size in the pow1 mutant. We further demonstrated that POW1 functions in grain size regulation by repressing the transactivation activity of the interacting protein TAF2, a highly conserved member of the TFIID transcription initiation complex. Down‐regulation of TAF2 rescued the enlarged grain size of pow1 but had little effect on the increased leaf angle phenotype of the mutant. The separable functions of the POW1‐TAF2 and POW1‐BR modules in grain size and leaf angle control provide a promising strategy for designing varieties with compact plant architecture and increased grain size, thus promoting high‐yield breeding in rice.

Manipulated Crystallization and Passivated Defects for Efficient Perovskite Solar Cells via Addition of Ammonium Iodide

Organic-inorganic metal halide perovskite materials have been widely studied as the light absorber for efficient photovoltaics. However, perovskite layers with defective nature are typically prepared with an uncontrollable crystallization process, intrinsically limiting further advance in device performance, and thus require delicate manipulation of crystallization processes and defect density. Here, we demonstrate an ammonium-assisted crystallization of perovskite absorbers during a two-step deposition to fabricate efficient solar cells. Addition of ammonium iodide (NH4I) is devised to manipulate the nucleation and crystal growth of perovskite, wherein the formation and transition of intermediate x[NH4+]•[PbI3]x- enables high-quality perovskite layers with an enlarged grain and reduced defect density. As a result, the perovskite solar cells (PSCs) achieve an average efficiency of 21.36% with a champion efficiency of 22.15% and improved environmental stability over 30 days in ambient conditions with varied relative humidity. These results with addition of NH4I provide an available and ingenious way to construct high-quality perovskite layers for efficient solar cells and will advance the commercial application of perovskite-based photovoltaics.