a b s t r a c tZinc oxide (ZnO) based fibers with a diameter of 80-100 nm were prepared by electrospinning. Polyvinyl alcohol (PVA) and zinc acetate dihydrate were dissolved in water and the polymer/salt solution was electrospun at 2.5 kV cm −1 . The resulting electrospun fibers were subjected to calcination at 500• C for 2 h to obtain ZnO-based fibers. Humidity sensing properties of the fiber mats were investigated by quartz crystal microbalance (QCM) method and electrical measurements. The adsorption kinetics under constant relative humidity (RH) between 10% and 90% were explained using Langmuir adsorption model. Results of the measurements showed that ZnO-based fibers were found to be promising candidate for humidity sensing applications at room temperature.

aeWe report a simple synthetic route to fabricate crystalline ZnO and CeO 2 /ZnO nanofibrous mats and their sensing characteristics against volatile organic compounds (VOCs) such as benzene, propanol, ethanol, and dichloromethane. Precursor fibers were fabricated by electrospinning of poly(vinyl alcohol) and metal salt(s) at 2.5 kV cm À1 in aqueous solution. The fibers were directly deposited on the crystal surface of a quartz crystal microbalance (QCM). The crystal, which was coated by nanostructured PVA/metal precursor(s) fibers, was subjected to calcination in air at 500 1C for 5 h. The formation of an oxide based nanofiber mat was revealed by scanning electron microscopy and X-ray diffraction. Upon exposure of the nanofiber mats to the VOCs, the compounds adsorbed onto the surface of oxidic fibers. The physisorption of the compounds was confirmed by FTIR and QCM. Both systems showed sensitivity to the VOCs and they hold a broad promise particularly for sensing applications of volatile alcoholic compounds. The introduction of CeO 2 into the ZnO structure reduced the sensitivity of ZnO most probably due to the decrement of oxygen vacancies.

In this study, green-emitting nitrogen-doped carbon dots (N-CDots) were synthesized and incorporated into drop-cast composite films for use as color conversion layers in a white-LED configuration to generate white light. In order to resolve the red deficiency of this configuration, a commercial red phosphor was integrated into the system. Moreover, the N-CDots were also processed into polymer/N-CDot composite fibers, for which we determined the amount of N-CDots that yielded adequate white-light properties. Finally, we showed that white light with excellent properties could be generated by employing both of the fabricated N-CDot composites either as drop-cast films or composite fibers. Hence, N-CDots provide a promising alternative to inorganic phosphors that are commonly employed in white-LED configurations.

a b s t r a c tAn ultraviolet photodetector with an active layer of solution processed polymer:quantum dot hybrid is introduced. Poly[9,9-di-(2-ethylhexyl)-fluorenyl-2,7-diyl] represents the polymer and Zn 0.71 Cd 0.29 S is the quantum dot used for the device. Photophysical studies showed that an electron transfer from the polymer to the ternary quantum dot is thermodynamically favored. Quenching experiments performed between the polymer and quantum dot indicates the formation of a non-fluorescent complex with an association constant of 4.6 × 10 4 M −1 . The device structure of ITO/PEDOT:PSS/ADS231BE: 50 wt% Zn 0.71 Cd 0.29 S/Al yielded a photoresponsivity value of 324 mA/W at −4 V under 1 mW/cm 2 illumination at 365 nm at room temperature and this value is further increased to 380 mA/W as a result of annealing at 75 • C.

Counterfeiting is a growing issue and causes economic losses. Fluorescent inks containing In(Zn)P/ZnS/DDT core/shell colloidal nanoparticles are formulated and combined with a convenient optical device for authentication. The particle size...