Stable Methylammonium-Free p-i-n Perovskite Solar Cells and Mini-Modules with Phenothiazine Dimers as Hole-Transporting Materials

During the last decade,perovskite solar technologies underwent an impressive development,with power conversion efficiencies reaching 25.5%for single-junction devices and 29.8%for Silicon-Perovskite tandem configurations.Even though research mainly focused on improving the efficiency of perovskite photovoltaics(PV),stability and scalability remain fundamental aspects of a mature photovoltaics technology.For n-i-p structure perovskite solar cells,using poly-triaryl(amine)(PTAA)as hole transport layer(HTL)allowed to achieve marked improvements in device stability compared with other common hole conductors.For p-i-n structure,poly-triaryl(amine)is also routinely used as dopant-free hole transport layer,but problems in perovskite film growth,and its limited resistance to stress and imperfect batch-to-batch reproducibility,hamper its use for device upscaling.Following previous computational investigations,in this work,we report the synthesis of two small-molecule organic hole transport layers(BPT-1,2),aiming to solve the above-mentioned issues and allow upscale to the module level.By using BPT-1 and methylammonium-free perovskite,max.Power conversion efficiencies of 17.26%and 15.42%on a small area(0.09 cm^(2))and mini-module size(2.25 cm^(2)),respectively,were obtained,with a better reproducibility than with poly-triaryl(amine).Moreover,BPT-1 was demonstrated to yield more stable devices compared with poly-triaryl(amine)under ISOS-D1,T1,and L1 accelerated life-test protocols,reaching maximum T_(90)values>1000 h on all tests.

Activity and Selectivity of Bimetallic Catalysts Based on SBA-15 for Nitrate Reduction in Water

Nitrate from the application of nitrogen-based fertilizers in intensive agriculture is a notorious waste product, though it lacks cost-effective solutions for its removal from potential drinking water resources. Catalytic reduction appears to be a promising technique for converting nitrates to benign nitrogen gas. Mesoporous silica SBA-15 is a frequently used catalyst support that has large surface areas and highly ordered nanopores. In this work, mesoporous silica SBA-15 bimetallic catalysts for nitrate reduction were investigated. The catalyst was optimized for the selection of promoter metal (Sn and Cu), noble metal (Pd and Pt) and loading ratios of these metals at different temperatures and reduction conditions. The catalysts prepared were characterized by FT-IR, N2 physisorption, XRD, SEM, and ICP. All catalysts showed the presence of cylindrical mesoporous channels and uniform pore structures that remained even after metals loading. In the presence of a CO2 buffer, the catalysts 4Pd-1Cu/SBA-15 and 1Pt-1Cu/SBA-15 reduced at 100?C under H2 and 1Pd-1Cu/SBA-15 reduced at 200°C under H2 demonstrated very high nitrate conversion. Furthermore, the forementioned Pd catalysts had higher N2 selectivity (88% - 87%) compared to Pt catalyst (80%). Nitrate conversion by the 4Pd-1Cu/SBA-15 catalyst was significantly decreased to 81% in the absence of CO2.

Synthesis and Crystal Structure of 1-(4-Chlorophenyl)-2-cyano-3-amino-3a-hydroxy- 3a,3b,6,7-tetrahydrobenzo[4,5]indene

The title compound 1-（4-chlorophenyl）-2-cyano-3-amino-3a-hydroxy-3a,3b,6,7- tetrahydro-benzo[4,5]indene 2, has been synthesized by the reductive cyclization of 2-cyano-3- （4-chlorophenyl）-3-（1-tetralon-2-yl） propionitrile 1 induced by low-valent titanium reagent and its structure was determined by single-crystal X-ray diffraction. The crystal belongs to monoclinic, space group C2/c with a = 28.244（7）, b = 14.401（3）, c = 21.245（3）A,β= 115.71（2）°, V = 7786（3）A^3, Mr= 696.13, Dc = 1.188 g/cm^3, Z = 8,μ（MoKα） = 0.208 mm^-1, F（000） = 2916, R = 0.0783 and wR = 0.2350. X-ray analysis reveals that the five-membered ring （C（7）～C（l l）） adopts an envelop conformation, while the six-membered ring （C（10）～C（14）, C（19）） has a half-chair conformation. Meanwhile, intermolecular H-bond interactions result in the formation of polymer.

Nanograded artificial nacre with efficient energy dissipation

The renowned mechanical performance of biological ceramics can beattributed to their hierarchical structures,wherein structural features atthe nanoscale play a crucial role.However,nanoscale features,such asnanogradients,have rarely been incorporated in biomimetic ceramicsbecause of the challenges in simultaneously controlling the materialstructure at multiple length scales.Here,we report the fabrication of artificial nacre with graphene oxide nanogradients in its aragonite plateletsthrough a matrix-directed mineralization method.The gradients areformed via the spontaneous accumulation of graphene oxide nanosheetson the surface of the platelets during the mineralization process,whichthen induces a lateral residual stress field in the platelets.Nanoindentation tests and mercury intrusion porosimetry demonstrate that the material's energy dissipation is enhanced both intrinsically and extrinsicallythrough the compressive stress near the platelet surface.The energydissipation density reaches 0.159±0.007 nJ/μm^(3),and the toughnessamplification is superior to that of the most advanced cer amics.Numer-ical simulations also agree with the finding that the stress field not ablycontributes to the overall energy dissipation.This work demonstratesthat the energy dissipation of biomimetic ceramics can be furtherincreased by integrating design principles spanning multiple scales.This strategy can be readily extended to the combinations of other struc-tural models for the design and fabrication of structural ceramics withcustomized and optimized performance.

Building egg-tray-shaped graphenes that have superior mechanical strength and band gap

The major hindrances of implementing graphene in two-dimensional(2D)electronics are both mechanical(the tendency to crumble and form ripples)and electrical(the lack of a band gap).Moreover,the inevitable structural defects in graphene have a profound influence on its physical and chemical properties.Here,we propose a family of 2D egg-tray graphenes constructed by arranging pentagon and heptagon defects in the graphene lattice based on a careful analysis of the topological distribution of minima,maxima,and saddle points.First-principles calculations show that the egg-tray graphenes are dynamically stable,and their energies,which depend on the concentration of pentagons and heptagons,are the lowest among carbon allotropes.These 2D carbon allotropes exhibit a large variation in their electronic properties,ranging from semimetallic to semiconducting,including some allotropes that have Dirac cones in their band structures.Furthermore,some egg-tray graphenes are predicted to have negative Poisson’s ratios.The adsorption of Li atoms on the egg-tray graphenes is considerably stronger than the adsorption on perfect graphene,therefore they may absorb Li more effectively than graphene,which is important for improving the performance of rechargeable Li batteries.

基于π-π/H-键协同作用制备含芘小分子增强高韧性石墨烯纸

轻质高强且具备高韧性的石墨烯组装材料在抗冲击防护领域有着潜在的应用价值.在这项工作中,我们通过在还原氧化石墨烯层间界面交联1-氨基芘AP和1-芘丁酸PB共轭小分子,可以获得具有高导电、高韧性的超强复合石墨烯纸(AP/PB-GPs).结果表明,超过10μm厚度的复合石墨烯纸具有超高的平均韧性(~69.67±15.3 MJ m^(-3)),同时抗拉伸强度接近1 GPa;尤其在抗冲击性能方面,在高速弹道冲击速度下,仍然可以获得优异的比穿透能量吸收值(~0.17 MJ kg^(-1)).详细的界面和结构分析表明,界面增强是由相邻石墨烯层间与共轭分子之间的π-π相互作用和氢键连接共同决定的.尤其是石墨烯纳米片内的孔洞及边缘缺陷更有利于共轭小分子充分的吸附,这必然会使界面结合最大化,在连续高的加载应力下能够有效促进裂纹的偏转和塑性变形.密度泛函理论(DFT)模拟表明,石墨烯纳米片边缘的–COOH极性官能团与AP/PB分子表面的–NH_(2)、–COOH之间的耦合对氢键网络的形成起着关键作用.