Nickel oxide thin films have been prepared from a nickel acetylacetonate (Ni(acac)) precursor for use in bulk heterojunction organic photovoltaic devices. The conversion of Ni(acac) to NiOx has been investigated. Oxygen plasma treatment of the NiO layer after annealing at 400 °C affords solar cell efficiencies of 5.2%. Photoelectron spectroscopy shows that high temperature annealing converts the Ni(acac) to a reduced form of nickel oxide. Additional oxygen plasma treatment further oxidizes the surface layers and deepens the NiO work function from 4.7 eV for the annealed film, to 5.0 eV allowing for efficient hole extraction at the organic interface.
Low-temperature solution-processable vanadium oxide (V2Ox) thin films have been employed as hole extraction layers (HELs) in polymer bulk heterojunction solar cells. V2Ox films were fabricated in air by spin-coating vanadium(V) oxytriisopropoxide (s-V2Ox) at room temperature without the need for further thermal annealing. The deposited vanadium(V) oxytriisopropoxide film undergoes hydrolysis in air, converting to V2Ox with optical and electronic properties comparable to vacuum-deposited V2O5. When s-V2Ox thin films were annealed in air at temperatures of 100 °C and 200 °C, OPV devices showed similar results with good thermal stability and better light transparency. Annealing at 300 °C and 400 °C resulted in a power conversion efficiency (PCE) of 5% with a decrement approximately 15% lower than that of unannealed films; this is due to the relative decrease in the shunt resistance (Rsh) and an increase in the series resistance (Rs) related to changes in the oxidation state of vanadium.
Pesticide usage is
one of the significant issues in modern
agricultural
practices; hence, monitoring pesticide content and its degradation
is of utmost importance. A novel and simple one-pot deep eutectic
solvent-based solvothermal method has been developed for the synthesis
of FeVO4/reduced graphene oxide (FeV/RGO) nanocomposite.
The band gap of FeV decreased upon anchoring with RGO. Enhanced activity
in the detection and photocatalytic degradation has been achieved
in the FeV/RGO nanocomposite compared to pure FeV and RGO. FeV/RGO
was used to modify glassy carbon electrode (GCE), and the fabricated
electrode was evaluated for its electrochemical detection of methyl
parathion (MP). The amperometric technique was found to be more sensitive
with a 0.001–260 μM (two linear ranges; 0.001–20
and 25–260 μM) wide linear range and low limit of detection
value (0.70 nM). The practical applicability of modified GCE is more
selective and sensitive to real samples like river water and green
beans. Photocatalytic degradation of MP has been examined using FeV,
RGO, and FeV/RGO nanocomposite. FeV/RGO managed to degrade 95% of
MP under solar light in 80 min. Degradation parameters were optimized
carefully to attain maximum efficiency. Degradation intermediates
were identified using liquid chromatography–mass spectrometry
analysis. The degradation mechanism has been studied in detail. FeV/RGO
could serve as a material of choice in the field of electrochemical
sensors as well as heterogeneous catalysis toward environmental remediation.
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