Efforts has been intensified in the field of research for nanomaterials to bridge the gap for energy supply in this century. A plant-based material that may provide solutions to the current energy crisis may be found in nanomaterials. Green synthesis of nanoparticles using plant extract is gaining importance as an alternative to conventional chemical and physical method of synthesis, because of its simplicity and environmental friendliness. In this research we synthesized Zinc oxide nanoparticle (ZnO.NPs) using plant extracts and deposited using spin-coating technique. The obtained samples were characterized by UltraViolet-Visible spectrophotometer, Fourier Transform Infra-Red spectroscopy (FTIR), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and Solar simulator for electrical properties. The maximum absorption peaks occurred at 235 nm, 250 nm, 270 nm, and 300 nm respectively but lower when compared with the bulk size that occurred at 350 nm and in the visible spectrum of the wavelength band. Band gap energy of zinc oxide nanoparticle at 500 rpm was 3.50 eV. ZnO.NPs FTIR spectrum was recorded in the range of 4000-500 cm −1 . The synthesis ZnO NPs FTIR result shows Zn-O functional group was found at low wavenumber. SEM images of the samples give information on the morphology which are spherical and granular nature. The XRD pattern of synthesized nanoparticles shows that the substances only belong to ZnO since there is no diffraction peaks of other impurities and the average grain size of the particles was estimated to be 14.7 nm. ZnO.NPs thin film device under illumination has efficiency of 0.7%. Based on electrical properties of the fabricated thin film device, the parameter shows it could be suitable for photoanode of Dye sensitized solar cell.

A plant that showed morphological closeness to Aspilia africana (Pers) C. D. Adams (Asteraceae) was spotted and collected in 2015 along Afe Babalola University road, Ado‐Ekiti, Ekiti State, Nigeria with coordinates 7°36′59.99″N, 5°12′60.00″E. However, upon closer observation some distinct and peculiar characteristics that clearly distinguished it from Aspilia africana were revealed, e.g. sterility of the disc florets and production of achenes by ray florets only. Another striking character of the plant was total emptying of the capitulum after achene maturation, leaving an empty capitulum cup on the plant. Literature and herbarium searches revealed that the plant had neither been reported from West Tropical Africa nor collected in any herbarium in Nigeria before. The plant was eventually identified as Melampodium divaricatum (L.) which is an annual erect herb, distributed in tropical and subtropical regions but mostly restricted to Mexico, North America and Central America. Morphological, reproductive and cytological studies carried out on the plant revealed it to possess a highly branched erect pigmented stem, simple opposite sub sessile leaves with acute apex and distantly serrated margins, capitula with yellow unisexual disc and ray florets, sterile disc florets, fertile ray florets, relatively high pollen fertility (92.85%), a somatic chromosome number of 2n = 24 and regular formation of 12 bivalents, indicating the plant to be a diploid species. Further studies on Melampodium in Nigeria and a general revision of the flora of West Tropical Africa is suggested as well as the need to monitor M. divaricatum in the region since it appears to have the capacity to become invasive.

This research work examines the structural and optical properties of ZnO thin films. Deposition were done by spin coating of solution of Zinc oxide onto pre-cleaned glass substrate at 4000 rpm for 30 sec using spin-coater under ambient condition at room temperature in order to form desired thickness of the film on the substrate. Post-deposition thermal annealing at different range of temperatures from 150°C to 600°C with steps of 50°C was carried out on the samples. The impact of thermal annealing on optical properties of the deposited thin film was investigated using UV-VIS spectrophotometer and scanning Electron Microscope for the morphology. The optical transmittance, reflectance, absorbance were recorded which was used to evaluate the optical band gap of Zinc oxide. Observation shows that band gap energy reduces as annealing temperature is increased from 150°C to 600°C. Observation made on the morphology using SEM model ASPEX 3020 showed that as the temperature increases the surface of the sample roughness increases. It was deduced that as the annealing temperature is increased the surface roughness increases. This may be due to increase in grain size with increase in annealing temperature. The band gap energy decreases as the annealing temperature increases.

A Blend of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C60-butyric acid methyl ester (PCBM), a fullerene derivate based donor-acceptor copolymer, is one of the widely used organic solar cell materials for photon-electron conversion. Thin films were developed, characterized, and optimized for optical absorbance. Absorption spectra were measured using a UV-VIS spectrophotometer. In this work, the effects of composition ratios of P3HT:PC 60 BM and various thicknesses was studied in ambient conditions. The P3HT:PC 61 BM thin film was deposited in two different composition ratio (1:1 and 1:3) and fabricated at seven different thicknesses of 20 nm, 30 nm, 35 nm, 87 nm, 98 nm, 115 nm, and 146 nm corresponding to spin coating speeds of 4000rpm, 3000rpm, 2000rpm, 1500rpm, 1250rpm, 1000rpm, and 750rpm, respectively. P3HT:PC 60 BM thin film composition ratio of 1:1 with thickness of 87nm shows relatively better photon absorption optical parameter than P3HT:PC 60 BM composition ratio of 1:3. P3HT: PC 61 BM solution coated at a spin speed of 1500 rpm shows a better absorption of photon energy. The results showed that the optimum thickness of the thin film is 87 nm at composition ratio of 1:1. Energy band gap values of composition ratio of 1:3 is observed to decreases with increase in spin-speed from 3.9 eV to 3.7 eV. The results can be used as a guideline for improving the design and fabrication of active layer of organic solar cells.