The synthesis of Pt doped WO3 nanosheets and application on colorimetric detection of cysteine by naked eye using response surface methodology for optimization.

We present a simple, sensitive, and specific colorimetric using the peroxidase properties method based on Pt doped WO3 nanosheets to detect the cysteine. Pt@WO3NSs were synthesized by hydrothermal method and characterized by Fourier transform infrared (FTIR), Transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction patterns (XRD) methods. The response surface methodology (RSM) method based on the central composite design (CCD) was used to optimize test parameters such as pH, nanosheet concentration, and temperature. When cysteine is present in the environment due to its competition with 3,3', 5,5'-Tetramethylbenzidine (TMB) in the use of hydrogen peroxide, the blue discoloration is reduced compared to the absence of cysteine and leads to its detection. We have favorably created a peculiar approach for sensing cysteine based on the colorimetric method in solution and paper with linear range 0.01-15 µM, 0.005-14 µM and R2 = 0.9887 and R2 = 0.9871 respectively. The detection limit for solution-based is 1.2 nM and for paper-based is 1 nM.

Nanoconfining solution-processed organic semiconductors for emerging optoelectronics.

Solution-processable organic materials for emerging electronics can generally be divided into two classes of semiconductors, organic small molecules and polymers. The theoretical thermodynamic limits of device performance are largely determined by the molecular structure of these compounds, and advances in synthetic routes have led to significant progress in charge mobilities and light conversion and light emission efficiencies over the past several decades. Still, the uncontrolled formation of out-of-equilibrium film microstructures and unfavorable polymorphs during rapid solution processing remains a critical bottleneck facing the commercialization of these materials. This tutorial review provides an overview of the use of nanoconfining scaffolds to impose order onto solution-processed semiconducting films to overcome this limitation. For organic semiconducting small molecules and polymers, which typically exhibit strong crystal growth and charge transport anisotropy along different crystallographic directions, nanoconfining crystallization within nanopores and nanogrooves can preferentially orient the fast charge transport direction of crystals with the direction of current flow in devices. Nanoconfinement can also stabilize high-performance metastable polymorphs by shifting their relative Gibbs free energies via increasing the surface area-to-volume ratio. Promisingly, such nanoconfinement-induced improvements in film and crystal structures have been demonstrated to enhance the performance and stability of emerging optoelectronics that will enable large-scale manufacturing of flexible, lightweight displays and solar cells.

Orienting and shaping organic semiconductor single crystals through selective nanoconfinement.

For organic semiconductor crystals exhibiting anisotropic charge transport along different crystallographic directions, nanoconfinement is a powerful strategy to control crystal orientation by aligning the fast crystallographic growth direction(s) with the unconfined axis(es) of nanoconfining scaffolds. Here, design rules are presented to relate crystal morphology, scaffold geometry, and orientation control in solution-processed small-molecule crystals. Specifically, organic semiconductor triisopropylsilylethynyl pyranthrene needle-like crystals with a dimensionality of n = 1 and perylene platelike crystals with n = 2 were grown from solution within nanoconfining scaffolds comprising cylindrical nanopores with a dimensionality of m = 1, representing one unconfined dimension along the cylinder axis, and those comprising nanopillar arrays with a dimensionality of m = 2. For m = n systems, native crystal growth habits were preserved while the crystal orientation in n = m direction(s) was dictated by the geometry of the scaffold. For n≠m systems, on the other hand, orientation control was restricted within a single plane, either parallel or perpendicular to the substrate surface. Intriguingly, control over crystal shape was also observed for perylene crystals grown in cylindrical nanopores (n > m). Within the nanopores, crystal growth was restricted along a single direction to form a needle-like morphology. Once growth proceeded above the scaffold surface, the crystals adopted their native growth habit to form asymmetric T-shaped single crystals with concave corners. These findings suggest that nanoporous scaffolds with spatially-varying dimensionalities can be used to grow single crystals of complex shapes.

Scaffold-Guided Crystallization of Oriented α-FAPbI3 Nanowire Arrays for Solar Cells.

Perovskite nanowire arrays with large surface areas for efficient charge transfer and continuous highly crystalline domains for efficient charge transport exhibit ideal morphologies for solar-cell active layers. Here, we introduce a room temperature two-step method to grow dense, vertical nanowire arrays of formamidinium lead iodide (FAPbI3). PbI2 nanocrystals embedded in the cylindrical nanopores of anodized titanium dioxide scaffolds were converted to FAPbI3 by immersion in a FAI solution for a period of 0.5-30 min. During immersion, FAPbI3 crystals grew vertically from the scaffold surface as nanowires with diameters and densities determined by the underlying scaffold. The presence of butylammonium cations during nanowire growth stabilized the active α polymorph of FAPbI3, precluding the need for a thermal annealing step. Solar cells comprising α-FAPbI3 nanowire arrays exhibited maximum solar conversion efficiencies of >14%. Short-circuit current densities of 22-23 mA cm-2 were achieved, on par with those recorded for the best-performing FAPbI3 solar cells reported to date. Such large photocurrents are attributed to the single-crystalline, low-defect nature of the nanowires and increased interfacial area for photogenerated charge transfer compared with thin films.