Stability Studies of Selected Metal Ions Chelates with 2-(4-amino-1,5- dimethyl-2-phenyl-1,2-dihydro-pyrazol-3-ylideneamino) Phenol

Acid dissociation and complex stability constants of 2-(4-Amino-1,5-dimethyl-2-phenyl-1,2-dihydro-pyrazol-3- ylideneamino) phenol (H2A) with some metal ions chelates have been determined potentiometrically using 0.1 M KCl and 20 % (v/v) ethanol-water mixture. The stability constants of the formed complexes were found to be in the order Re5+ > Ce3+ > Pd2+ >Th4+ > Hg2+ > Co2+. The dissociation constants (pKa) of H2A and the stability constants (log Ki) of their complexes were determined at 298, 308 and 318 K. The corresponding thermodynamic parameters (ΔG, ΔH and ΔS) were calculated and discussed. The results indicated that, the dissociation process is non-spontaneous, endothermic and entropically unfavorable. The formation of the metal complexes has been found to be endothermic and entropically favorabl

Single- and Multilayered Perovskite Thin Films for Photovoltaic Applications

Organic–inorganic lead halide perovskites materials have emerged as an innovative candidate in the development of optoelectronic and photovoltaic devices, due to their appealing electrical and optical properties. Herein, mix halide single-layer (~95 nm) and multilayer (average layer ~87 nm) CH3NH3PbIBr2 thinfilms were grown by a one-step spin coating method. In this study, both films maintained their perovskite structure along with the appearance of a pseudo-cubic phase of (200) at 30.16°. Single-layer and multilayer CH3NH3PbIBr2 thinfilms displayed leaky ferroelectric behavior, and multilayered thinfilm showed a leakage current of ~5.06 × 10−6 A and resistivity of ~1.60 × 106 Ω.cm for the applied electric field of 50 kV/cm. However, optical analysis revealed that the absorption peak of multilayered perovskite is sharper than a single layer in the visible region rather than infrared (IR) and near-infrared region (NIR). The band gap of the thinfilms was measured by Tauc plot, giving the values of 2.07 eV and 1.81 eV for single-layer and multilayer thinfilms, respectively. The structural analysis has also been performed by Fourier transform infrared spectroscopy (FTIR). Moreover, the fabricated CH3NH3PbIBr2 as an absorber layer for photoelectric cell demonstrated a power conversion efficiency of 7.87% and fill factor of 72%. Reported electrical, optical and photoelectric efficiency-based results suggest that engineered samples are suitable candidates for utilization in optoelectronic and photovoltaic devices