Controlling the Morphology and Interface of the Perovskite Layer for Scalable High-Efficiency Solar Cells Fabricated Using Green Solvents and Blade Coating in an Ambient Environment.

Low-cost and solution-processed perovskite solar cells have shown great potential for scaling-up mass production. In comparison with the spin coating process for fabricating devices with small areas, the blade coating process is a facile technique for preparing uniform films with large areas. High-efficiency perovskite solar cells have been reported using blade coating, but they were fabricated using the toxic solvent N,N-dimethylformide (DMF) in nitrogen. In this work, we present highly efficient blade-coated perovskite solar cells prepared using a green solvent mixture of γ-butyrolactone (GBL) and dimethyl sulfoxide (DMSO) in an ambient environment. By carefully controlling the interface, morphology, and crystallinity of perovskite films through composition variations and additives, a high power conversion efficiency of 17.02% is achieved in air with 42.4% reduction of standard deviation in performance. The findings in this work resolve the issues of scalability and solvent toxicity; thus, the mass production of perovskite solar cells becomes feasible.

Photodegradation Activity of Poly(ethylene oxide-b-ε-caprolactone)-Templated Mesoporous TiO2 Coated with Au and Pt.

Mesoporous TiO2 films are synthesized through evaporation-induced self-assembly using poly(ethylene oxide-b-ε-caprolactone) diblock copolymers as a soft-template. Using small-angle X-ray scattering and scanning electron microscopy, we investigate the effect of the TiO2/PEO-b-PCL ratio on the resulting nanoarchitectonic structure. After sputter-coating Au and Pt layers, these Au/TiO2 and Pt/TiO2 nanocomposite films display drastically enhanced photodegradation of rhodamine 6G under ultraviolet irradiation, due to the metal films inhibiting the rapid recombination of photogenerated charge carriers.

Tailored Design of Bicontinuous Gyroid Mesoporous Carbon and Nitrogen-Doped Carbon from Poly(ethylene oxide-b-caprolactone) Diblock Copolymers.

Highly ordered mesoporous resol-type phenolic resin and the corresponding mesoporous carbon materials were synthesized by using poly(ethylene oxide-b-caprolactone) (PEO-b-PCL) diblock copolymer as a soft template. The self-assembled mesoporous phenolic resin was found to form only in a specific resol concentration range of 40-70 wt % due to an intriguing balance of hydrogen-bonding interactions in the resol/PEO-b-PCL mixtures. Furthermore, morphological transitions of the mesostructures from disordered to gyroid to cylindrical and finally to disordered micelle structure were observed with increasing resol concentration. By calcination under nitrogen atmosphere at 800 °C, the bicontinuous mesostructured gyroid phenolic resin could be converted to mesoporous carbon with large pore size without collapse of the original mesostructure. Furthermore, post-treatment of the mesoporous gyroid phenolic resin with melamine gave rise to N-doped mesoporous carbon with unique electronic properties for realizing high CO2 adsorption capacity (6.72 mmol g-1 at 0 °C).

Flexible Epoxy Resin Formed Upon Blending with a Triblock Copolymer through Reaction-Induced Microphase Separation.

In this study, we used diglycidyl ether bisphenol A (DGEBA) as a matrix, the ABA block copolymer poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) (Pluronic F127) as an additive, and diphenyl diaminosulfone (DDS) as a curing agent to prepare flexible epoxy resins through reaction-induced microphase separation (RIMPS). Fourier transform infrared spectroscopy confirmed the existence of hydrogen bonding between the poly(ethylene oxide) segment of F127 and the OH groups of the DGEBA resin. Small-angle X-ray scattering, atomic force microscopy, and transmission electron microscopy all revealed evidence for the microphase separation of F127 within the epoxy resin. Glass transition temperature (Tg) phenomena and mechanical properties (modulus) were determined through differential scanning calorimetry and dynamic mechanical analysis, respectively, of samples at various blend compositions. The modulus data provided evidence for the formation of wormlike micelle structures, through a RIMPS mechanism, in the flexible epoxy resin upon blending with the F127 triblock copolymer.

Hybrid Mesoporous Silicas and Microporous POSS-Based Frameworks Incorporating Evaporation-Induced Self-Assembly.

We fabricated a series of mesoporous silicas and mesoporous organosilicates with hierarchical porosity through evaporation-induced self-assembly using Pluronic F127 as a template in this study. We could tailor the mesophase of each mesoporous silica sample by varying the weight ratio of its two silica sources: tetraethyl orthosilicate (TEOS) and triethoxysilane hydrosilylated octavinyl polyhedral oligomeric silsesquioxane (OV-POSS-SILY). The mesophases ranged from an ordered body-centered cubic (bcc) structure (TEOS alone) to ordered face-centered cubic (fcc) structure (10 and 20 wt.% of OV-POSS-SILY) and finally to disordered spherical pores (≥30 wt.% of OV-POSS-SILY). We used small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) to study the transformations of these mesophases, while N2 isotherm sorption curves revealed the porosities of these mesoporous silicate samples. Moreover, 29Si CP/MAS solid state nuclear magnetic resonance spectroscopy allowed us to analyze the compositions of the POSS-containing silicate frameworks. Such functional mesoporous silica samples incorporating microporous POSS building units have potential applications in various systems, including optical and electronic devices.

Tunable mesoporous lamellar silicas prepared using poly(ethylene oxide-b-L-lactide) and poly(ethylene-b-ethylene oxide-b-L-lactide) block copolymers as templates.

In this study, we synthesized poly(ethylene oxide-b-L-lactide) (PEO-PLLA) diblock copolymers and poly(ethylene-b-ethylene oxide-b-L-lactide) (PE-PEO-PLLA) triblock terpolymers as templates for the preparation of mesoporous lamellar silicas, possessing single, bimodal, or trimodal pore size distributions, through an evaporation-induced self-assembly (EISA) approach. As templates, we synthesized the diblock copolymers EO114LLA26 and EO114LLA130 and the triblock terpolymers E13EO42LLA26 and E13EO42LLA35 using simple ring-opening polymerization. Small-angle X-ray scattering, transmission electron microscopy, and N2 sorption measurements revealed that the mesoporous silicas displayed the morphologies of either lamellar silica walls featuring a distribution of many short cylindrical mesopores or pure lamellar structures. The morphology was greatly affected by the nature of the template (diblock or triblock copolymer) and the molecular weight of the PLLA segment in the block copolymer.

Hydrogen Bonding-Mediated Microphase Separation during the Formation of Mesoporous Novolac-Type Phenolic Resin Templated by the Triblock Copolymer, PEO-b-PPO-b-PEO.

After blending the triblock copolymer, poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) (PEO-b-PPO-b-PEO) with novolac-type phenolic resin, Fourier transform infrared spectroscopy revealed that the ether groups of the PEO block were stronger hydrogen bond acceptors for the OH groups of phenolic resin than were the ether groups of the PPO block. Thermal curing with hexamethylenetetramine as the curing agent resulted in the triblock copolymer being incorporated into the phenolic resin, forming a nanostructure through a mechanism involving reaction-induced microphase separation. Mild pyrolysis conditions led to the removal of the PEO-b-PPO-b-PEO triblock copolymer and formation of mesoporous phenolic resin. This approach provided a variety of composition-dependent nanostructures, including disordered wormlike, body-centered-cubic spherical and disorder micelles. The regular mesoporous novolac-type phenolic resin was formed only at a phenolic content of 40-60 wt %, the result of an intriguing balance of hydrogen bonding interactions among the phenolic resin and the PEO and PPO segments of the triblock copolymer.

Catalytic reduction of hydrazine to ammonia by a vanadium thiolate complex.

Vanadium(III) thiolate complexes, [V(PS3'')(Cl)]- [1a; PS3'' = P(C6H3-3-Me3Si-2-S)3(3-)] and [V(PS3')(Cl)]- [1b; PS3' = P(C6H3-5-Me-2-S)3(3-)], were synthesized and characterized. Complex 1a serves as a precursor for the catalytic reduction of hydrazine to ammonia. The spectroscopic and electrochemical studies indicate that hydrazine is bound and activated in a V(II) state.

The first example of a seven-coordinate vanadium(III) thiolate complex containing the hydrazine molecule, an intermediate of nitrogen fixation.

The first example of a seven-coordinate vanadium(III) thiolate complex, [V(PS3' ')(N(2)H(4))(3)] (1), where PS3' ' = [P(C(6)H(3)-3-Me(3)Si-2-S)(3)](3)(-), has been synthesized and characterized. Compound 1 contains a tetradentate ligand (PS3' ') and three hydrazine molecules, forming a capped octahedral geometry. A five-coordinate vanadium(III) complex, [V(PS3)(1-Me-Im)] (2), where PS3 = [P(C(6)H(4)-2-S)(3)](3)(-) and 1-Me-Im = 1-methyl-imidazole, was also obtained. Compound 2 adopts a trigonal bipyramidal geometry, in which the vanadium is ligated by the title ligand, PS3, and one 1-Me-Im molecule.