The recent advances in perovskite solar cells (PSCs) created a tsunami effect in the photovoltaic community. PSCs are newfangled high-performance photovoltaic devices with low cost that are solution processable for large-scale energy production. The power conversion efficiency (PCE) of such devices experienced an unprecedented increase from 3.8 % to a certified value exceeding 20 %, demonstrating exceptional properties of perovskites as solar cell materials. A key advancement in perovskite solar cells, compared with dye-sensitized solar cells, occurred with the replacement of liquid electrolytes with solid-state hole-transporting materials (HTMs) such as 2,2',7,7'-tetrakis-(N,N-di-4-methoxyphenylamino)-9,9'-spirobifluorene (Spiro-OMeTAD), which contributed to enhanced PCE values and improved the cell stability. Following improvements in the perovskite crystallinity to produce a smooth, uniform morphology, the selective and efficient extraction of positive and negative charges in the device dictated the PCE of PSCs. In this Review, we focus mainly on the HTMs responsible for hole transport and extraction in PSCs, which is one of the essential components for efficient devices. Here, we describe the current state-of-the-art in molecular engineering of hole-transporting materials that are used in PSCs and highlight the requisites for market-viability of this technology. Finally, we include an outlook on molecular engineering of new functional HTMs for high efficiency PSCs.

No abstract

No abstract

Micellization (aggregation) phenomenon of amphiphilic phenothiazine drug promazine hydrochloride (PMZ) and sodium dodecylbenzenesulfonate (SDBS) mixtures in absence and attendance of 50 mmol•kg À1 NaCl (salt)/300 mmol•kg À1 urea was investigated conductometrically at five various temperatures (293.15-318.15 K) at gaps of T = 5 K. PMZ is employed for the cure of mania and schizophrenia. The critical micelle concentration (CMC) values have been evaluated and defined in terms of hydrophobicity and hydrophilicity of PMZ and SDBS in aqueous and nonaqueous solutions. With increasing the temperature, the CMC first increases then decreases. At 303.15 K, the maximum CMC values were obtained in absence and presence of NaCl/urea. NaCl reduces the CMC of pure amphiphiles and their mixtures while urea increases. Various physicochemical parameters such as CMC id (ideal critical micelle concentration), micellar mole fraction of SDBS (X 1 ) (calculated by different proposed models), and interaction parameter have been evaluated and discussed in detail. The values of degree of dissociation (g) and CMC of the micelles were utilized to evaluate the different thermodynamic parameters. Activity coefficients (f 1 and f 2 ) and excess free energy of micellization (ΔG ex ) values were also evaluated. All outcomes obtained herein show attractive interactions in the mixtures of PMZ and SDBS.

No abstract

No abstract

aIn the present paper, reaction of zinc-glycylphenylalanine ([Zn(II)-Gly-Phe] + ) with ninhydrin has been investigated in gemini (m-s-m type; m = 16, s = 4-6) surfactants at temperature (70°C) and pH (5.0). Monitoring the appearance of product at 400 nm was used to follow the kinetics, spectrophotometrically. The order of the reaction with respect to [Zn(II)-Gly-Phe] + was unity while with respect to [ninhydrin] was fractional. The reaction constants involved in the mechanism were obtained. In addition to the rate constant (k Ψ ) increase and leveling-off regions are observed with the geminis, just like as seen with conventional surfactant hexadecyltrimethylammonium bromide (CTAB), the former produced a third region of increasing k Ψ at higher concentrations. A close agreement between observed and calculated rate constants was found under varying experimental conditions. A suitable mechanism consistent with the experimental findings has been proposed.

The micellization of amphiphilic drug amitriptyline hydrochloride (AMT, an antidepressant) and conventional as well as gemini surfactants has been studied conductometrically in pure and mixed states in aqueous solutions at different temperatures to derive various physicochemical properties such as critical micelle concentration (cmc), ideal cmc (cmc(id)), counterion dissociation (g), standard Gibbs free energy (DeltaG(m)(0)), enthalpy (DeltaH(m)(0)), and entropy of micellization (DeltaS(m)(0)), micellar mole fractions of surfactant (X1, X1(m)), mole fraction of surfactant in ideal state (X1(id)), interaction parameter (beta), activity coefficients (f1, f2), and excess free energy of mixing (DeltaG(ex)). All the results indicate synergism and attractive interactions in the mixed systems.