[en] Highlights: • VOPcPhO:P3HT micro-structures with nano-porous surface morphology have been formed. • Multidimensional structures have been formed by electro-spraying technique. • The electro-sprayed films are very promising for the humidity sensors. - Abstract: In this paper, composite micro-structures of Vanadyl 2,9,16,23-tetraphenoxy-29H,31H-phthalocyanine) (VOPcPhO) and Poly (3-hexylthiophene-2,5-diyl) (P3HT) complex with nano-porous surface morphology have been developed by electro-spraying technique. The structural and morphological characteristics of the VOPcPhO:P3HT composite films have been studied by field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). The multidimensional VOPcPhO:P3HT micro-structures formed by electro-spraying with nano-porous surface morphology are very promising for the humidity sensors due to the pore sizes in the range of micro to nano-meters scale. The performance of the VOPcPhO:P3HT electro-sprayed sensor is superior in term of sensitivity, hysteresis and response/recovery times as compared to the spin-coated one. The electro-sprayed humidity sensor exhibits ∼3 times and 0.19 times lower hysteresis in capacitive and resistive mode, respectively, as compared to the spin-coated humidity sensor.

[en] The present study demonstrates a novel nanoporous structure of aluminium 1,8,15,22-tetrakis 29H,31H phthalocyanine chloride (AlPcCl) prepared by template-assisted method for a humidity sensor. The nanoporous sensing layer was fabricated by solution wetting of anodic aluminium oxide template. The solutions of AlPcCl in different concentrations were spun cast over the template at various speeds. Both capacitive and resistive responses were measured as a function of different relative humidity levels. The sensor showed wide operating relative humidity range and responded at quite low humidity levels. Morphological changes were investigated by field emission scanning electron microscopy. The sensor showed wide operating relative humidity range. The sensor demonstrated better performance with improved sensing parameters, highlighting unique advantages of the low-molecular nanostructured sensing layer for the humidity sensors.

[en] The optoelectronics and spectroscopic properties of N, N-diphenyl-N, N-bis(3-methylphenyl)-1, 1-biphenyl-4.4 diamine: tris (8-hydroxyquinolinate) aluminum (TPD:Alq3) systems were investigated for the application of ultraviolet (UV) sensors. Solution processed spin coating technique was used to deposit the films on quartz and to fabricate the devices on ITO-integrated substrates. Results showed that UV absorption of TPD was improved by its doping with Alq3 acceptor in a 1:2 volumetric ratio, thereby reducing its energy gap from 3.08 eV to 2.95 eV. The electronic transition in TDP was found to be direct forbidden, but changed to direct allowed transition by Alq3 dopant. Larger photocurrent, increased exciton generation and improved UV sensing was achieved for TPD:Alq3 (1:2) based UV detectors compared to that of the TPD-based devices. The signal to noise ratio was increased when Alq3 content was added up to 1:2 volumetric ratio, while it was decreased when higher amount of Alq3 was added.

[en] In this work, a broad investigation on the optical parameters of TPD:Alq3 composite thin films is reported. The films are prepared from different solution-processed mixtures and are deposited onto the quartz substrate in order to measure their optical response with UV–Vis–NIR spectrophotometer. Results showed that the non-dispersive refractive index and dielectric constant of TPD was increased from 1.49 to 1.75 and from 2.19 to 2.99 by Alq3 doping, respectively. The optical conductivity of TPD:Alq3 (1:3) composite was seen to be highly improved, reaching the value of 144 S/cm. The Wemple and DiDomenico (WD) model was used to find the band gap ($E_g^{WD}$) of the films and results were compared to those deduced from the Tauc's equation ($E_g^{opt}$). It was found that the investigated films obey the single-oscillator model in defining the strength of the optical transitions.

[en] Alone, it is expected, and also was experimentally proved, that calcium carbonate and reduced graphene oxide do have negligible specific capacitance due to the chemical composition of both materials. However, synthesis of CaCO₃ on the form of very thin sporadic layer attaching rGO results in dramatic increase in the specific capacitance of the obtained composite due to formation of the electrochemical double layer at the interfacial area. Moreover, the specific capacitance could be further enhanced by nitrogen-doping of the rGO sheets. Typically, a novel N-rGO/CaCO₃ composite has been successfully synthesized by heat reflux strategy with graphite powder, calcium acetate and urea as raw materials.The composite was characterized by X-Ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), field-emission scanning electron microscopy (FESEM), coupled with rapid EDAX (energy dispersive analysis of X-Ray) and X-ray photoelectron spectroscopy. The utilized physiochemical characterizations indicated that the final prepared composite can be demonstrated as N-doped rGO decorated by very thin discrete layer from calcium carbonate. Supercapacitive performance of N-rGO/CaCO₃ composite has been investigated by cyclic voltammetry (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy in 1 M KOH solution. The results reveal that the N-rGO/CaCO₃ composite delivers a large specific capacitance of as high as 214 Fg⁻¹ and 188 Fg⁻¹ at 5 mV s⁻¹and 1.0 Ag⁻¹, according to CV and galvanostatic charge-discharge tests, respectively; while the CaCO₃, rGO, rGO/CaCO₃, N-rGO based electrodes has a poor electrochemical performance at the same conditions. Moreover, the as-prepared composite exhibited excellent long cycle stability with about 88.7% specific capacitance retained after 10,000 cycles.