Cesium Halides-Assisted Crystal Growth of Perovskite Films for Efficient Planar Heterojunction Solar Cells

Efficient planar heterojunction perovskite solar cells were successfully demonstrated by using a two-step film fabrication method with postinterdiffusion of cesium halides and formamidinium iodide (FAI). It is found that the incorporation of a small fraction of cesium halides, such as CsI and CsBr, into FAPbI₃(Cl) lattice could effectively increase the grain size and film quality, leading to improved and balanced charge mobility, reduced carrier recombination, and long carrier lifetime. With these, the cesium halides-based perovskite films fabricated using our method result in a champion device with a power conversion efficiency (PCE) of 20.43% and a stabilized PCE of 19.60%, combined with a very notable fill factor (FF) of 81.58%, which could be mainly attributed to the increased grains size of perovskite film with reduced carrier recombination

Selenophene-Based 2D Ruddlesden-Popper Perovskite Solar Cells with an Efficiency Exceeding 19%

Two-dimensional (2D) Ruddlesden-Popper (RP) perovskites have emerged as attractive candidates for high-performance perovskite solar cells (PSCs) thanks to their superior environmental and structural stability. However, 2D RP PSCs exhibit larger exciton binding energy due to the dielectric mismatch between the organic and inorganic layers, resulting in poorer photovoltaic performance compared to their 3D analogs. Here, we developed a selenophene-based spacer, namely, 2-selenophenemethylammonium (SeMA), for stable and efficient 2D RP PSCs. The 2D perovskite film using methylammonium (MA) as the A-site cation (nominal n = 5) shows excellent film quality with large grain size and a preferred vertical orientation relative to the substrate. Furthermore, we have successfully demonstrated the effectiveness of a predeposition transport layer (PDTL) consisting of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) in passivating surface defects of the perovskite film and inducing densification of the upper PCBM electron transport layer. This densification promotes efficient extraction and transport of electrons. The optimized PSCs based on 2D RP perovskite using MA as A-site cation (nominal n = 5) achieved a power conversion efficiency (PCE) of 17.25%, which was further boosted to 19.03% when using formamidinium (FA) as A-site cation. This represents a record PCE of 2D RP PSCs by using the selenophene-based spacer. Moreover, these 2D RP PSCs significantly improve thermal, moisture, and light stability. Our results provide significant implications for the synergistic strategy of developing selenophene-based spacers and device engineering methods for achieving highly efficient and stable 2D RP perovskite solar cells

RNAi<b>-</b>Directed Downregulation of Vacuolar H⁺<b>-</b>ATPase Subunit A Results in Enhanced Stomatal Aperture and Density in Rice

<div><p>Stomatal movement plays a key role in plant development and response to drought and salt stress by regulating gas exchange and water loss. A number of genes have been demonstrated to be involved in the regulation of this process. Using inverse genetics approach, we characterized the function of a rice (<i>Oryza sativa</i> L.) vacuolar H⁺-ATPase subunit A (<i>OsVHA-A</i>) gene in stomatal conductance regulation and physiological response to salt and osmotic stress. <i>OsVHA-A</i> was constitutively expressed in different rice tissues, and the fusion protein of GFP-OsVHA-A was exclusively targeted to tonoplast when transiently expressed in the onion epidermal cells. Heterologous expression of <i>OsVHA-A</i> was able to rescue the yeast mutant <i>vma1Δ</i> (lacking subunit A activity) phenotype, suggesting that it partially restores the activity of V-ATPase. Meanwhile, RNAi-directed knockdown of <i>OsVHA-A</i> led to a reduction of vacuolar H⁺-ATPase activity and an enhancement of plasma membrane H⁺-ATPase activity, thereby increasing the concentrations of extracellular H⁺ and intracellular K⁺ and Na⁺ under stress conditions. Knockdown of <i>OsVHA-A</i> also resulted in the upregulation of <i>PAM3</i> (<i>plasma membrane H⁺-ATPase 3</i>) and downregulation of <i>CAM1</i> (<i>calmodulin 1</i>), <i>CAM3 (calmodulin 3</i>) and <i>YDA1</i> (<i>YODA</i>, a MAPKK gene). Altered level of the ion concentration and the gene expression by knockdown of <i>OsVHA-A</i> probably resulted in expanded aperture of stomatal pores and increased stomatal density. In addition, <i>OsVHA-A</i> RNAi plants displayed significant growth inhibition under salt and osmotic stress conditions. Taken together, our results suggest that <i>OsVHA-A</i> takes part in regulating stomatal density and opening via interfering with pH value and ionic equilibrium in guard cells and thereby affects the growth of rice plants.</p></div

Neoarchaean crustal growth by combined arc–plume action: evidence from the Kadiri Greenstone Belt, eastern Dharwar craton, India

<p>Field and geochemical studies combined with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) zircon U–Pb dating set important constraints on the timing and petrogenesis of volcanic rocks of the Neoarchaean Kadiri greenstone belt and the mechanism of crust formation in the eastern Dharwar craton (EDC). The volcanic rocks are divided into three suites: tholeiitic basalts, calc-alkaline high-Mg# andesites and dominant dacites–rhyolites. The basalts (pillowed in places) show flat rare earth element (REE) and primordial mantle-normalized trace element patterns, but have minor negative Nb and Ta anomalies. They are interpreted as mantle plume-related oceanic plateau basalts whose source contained minor continental crustal input. The andesites are characterized by high Mg# (0.66–0.52), Cr and Ni, with depletion of high-field strength elements (HFSE) and enrichment of light REE (LREE) and large-ion lithophile elements (LILE). They were probably derived from a metasomatized mantle wedge overlying a subducted slab in a continental margin subduction zone. The dacites–rhyolites are silicic rocks (SiO₂=61–72 wt%) with low Cr and Ni, K₂O/Na₂O mostly 0.5–1.1, highly fractionated REE patterns, enrichments of LILE and distinctly negative HFSE anomalies. One rhyolite sample yielded a zircon U–Pb age of 2353±32 Ma. This suite is similar to potassic adakites and is explained as the product of deep melting of thickened crust in the arc with a significant older crustal component. Collision between a continental margin arc with an oceanic plateau followed by slab break-off, upwelling of hot asthenosphere and extensive crustal reworking in a sustained compressional regime is proposed for the geodynamic evolution of the area. This is in corroboration with the scenario of EDC as a Neoarchaean hot orogen as suggested recently by some workers. </p

The H⁺ efflux in <i>OsVHA</i><i>-</i><i>A</i>-RNAi lines.

<p>(A) Plasma membrane H⁺-ATPase activity was determined in wild type (WT) and three <i>OsVHA-A</i> RNA interference lines (<i>OsV-5</i>, <i>OsV-11</i>, and <i>OsV-18</i>). (B) Plasma membrane H⁺-ATPase proton-pumping measured by the quenching of ACMA fluorescence. Ten micrograms of tonoplast vesicles were applied to detect fluorescence density. (C) The H⁺ fluxes determined by micro-test system in wild type and transgenic line (<i>OsV-5</i>) under normal (CK) and 20% PEG6000 treatment (PEG). The positive values mean ion effluxes, whereas negative values show ion influx. Values are means ± SE (n  = 6). Asterisks (*) indicate significant differences from WT at <i>P</i><0.05.</p

Phenotypes of WT and transgenic seedlings grown on MS media with different concentrations of mannitol.

<p>One-week-old wild type (WT) and transgenic (<i>OsV-5</i>, <i>OsV-11</i>, <i>OsV-18</i>) seedlings grown on MS media with 0, 150, 200 mM mannitol, respectively. Results shown are representative. Shoot length, root length, and fresh weight were shown in (B), (C), and (D), respectively. Twenty-day-old wild type (WT) and transgenic plants (<i>OsV-5</i>, <i>OsV-11</i>, <i>OsV-18</i>) were treated with or without 20% PEG6000 for 21 d. Osmolality (C) and leaf conductance (D) from 10 fully expanded leaves of these plants were measured. Asterisks (*) indicate significant differences from WT at <i>P</i><0.05.</p

V-ATPase, PPase activity assays and vacuolar pH measurements in <i>OsVHA</i><i>-</i><i>A</i> RNAi transgenic lines.

<p>(A) Vacuolar H⁺-ATPase activity and (B) V-PPase activity were determined in wild type (WT) and three <i>OsVHA-A</i> RNA interference lines (<i>OsV-5</i>, <i>OsV-11</i>, and <i>OsV-18</i>). (C) The images showing emission intensities of vacuoles from epidermal root cells loaded with BCECF AM. Results shown are representative. Scale bars  = 100 μM. (D) The vacuolar pH values calculated from (C). (E) V-ATPase proton-pumping measured by the quenching of ACMA fluorescence. Ten micrograms of tonoplast vesicles were applied to detect fluorescence density. Each bar represents three replications. Asterisks (*) indicate significant differences from WT at <i>P</i><0.05.</p

Phenotypes of WT and transgenic seedlings grown on MS media adding different concentrations of NaCl.

<p>(A) One-week-old wild type (WT) and transgenic (<i>OsV-5</i>, <i>OsV-11</i>, <i>OsV-18</i>) seedlings grown on MS media with 0, 100, 140 mM NaCl, respectively. Results shown are representative. Shoot length, root length, and fresh weight were shown in (B), (C), and (D), respectively. Contents of Na⁺ (E) and K⁺ (F) in WT and transgenic seedlings from (A) were shown. Asterisks (*) indicate significant differences from WT at <i>P</i><0.05.</p

Yeast complementation assay.

<p>Wide type (WT) yeast stain BY4741, OsVHA-A ortholog mutant (<i>vma1Δ</i>), and yeast transformants with pYES2 vector, pYES2-OsVHA-A (OsVA), respectively, grown on YPG (pH 5.5), YPG (pH 7.5) and YPG (pH 7.5, 100 mM CaCl₂) solid media. Results shown are representative.</p

Schematical model of <i>OsVHA-A</i>-RNAi in the regulation of stomatal aperture.

<p>Schematical model of <i>OsVHA-A</i>-RNAi in the regulation of stomatal aperture.</p