Search results

The study aims to carry out the production of a bulk heterojunction organic solar cell in a laboratory scale using a blend of poly (3-hexylthiopene) (P3HT) and [6, 6]-phenyl (C61) butyric acid methyl ether (PCBM).

Four inverted geometry organic solar cells were prepared based on 1:1 ratio of P3HT to PCBM and subjected to post annealing at different temperatures of 32, 120, 130 and 140°C. Solar cells were fabricated with structure glass/ITO/P3HT:PCBM/PEDOT:PSS/Au and characterized using Keithley 2400 series sourcemeter and a multimeter interfaced to a computer system with a LabVIEW software, which showed both dark and illumination current–voltage characteristic curves. Four reference cells were also fabricated with structure soda lime glass/P3HT:PCBM and annealed at different temperatures of 32, 120, 130 and 140°C.

The third organic solar cell prepared, Sample CITO, had the best performance with power conversion efficiency (PCE) of 2.0281 per cent, fill factor (FF) of 0.392, short circuit current of −0.0133 A and open circuit voltage of 0.389 V. Annealing of active layer was found to improve cell morphology, FF and PCE. Annealing of the active layer at 140°C resulted in a decrease of the PCE to 2.01 per cent.

These findings are in good agreement with previous investigation in literature which reported that best annealing temperature for a 1:1 ratio blend of active material is 130°C. Ultraviolet–visible spectra on reference cells showed that sample CITO had wider absorption spectra with peak absorbance at a wavelength of 508 nm.

This research is purely original.

A novel cost-effective bio-digester was explored to convert biological waste into useful clean energy. The bioreactor was aimed to anaerobically digest locally sourced cow dung and chicken droppings.

The design consideration is a batch horizontal 267 L digester made from cast iron with centrally positioned four-impeller shaft to enhance mixing. The system operated with a retention time of 63 days and a substrate (cow dung and poultry waste) ratio of 1:2 and water substrate ratio of 1:0.5 in the gasholder system. The purification, compression and performance evaluation of the generated biogas were also conducted.

The total volume of gas produced for each substrate compositions designed over 14 days ranges between 49.34 and 52.91 mL/day. The optimal value of 52.45 ml using cow dung and poultry waste (w/w) 20:80 was obtained. The average ambient temperatures during the study were within the mesophilic range of 20-40°C. The pH values were stable and always in the optimal range of 6.5-8.0. The reductions in moisture content, ash content, total solids and volatile solids were from 80.50-0.20 per cent, 39.60-14 per cent, 18.50-5.90 per cent and 11.60-4.90 per cent, respectively.

The developed digester is cost-effective and would help minimize solid waste disposal. The estimated methane contents of the gas from cow dung and chicken waste after scrubbing were found to be 71.95 per cent and could be harnessed in solving the energy crisis in the developing nations.

This study aims to comparatively discuss the effect of lean manufacturing (LM) implementation in the manufacturing sectors of developing and developed countries.

An in-depth literature review focused on previous research published between 2015 and March 2020. The papers published by the databases such as Google Scholar, Scopus, ProQuest and Web of Science were used in the study. A total of 63 studies that focused on LM application in manufacturing industries in developing and developed countries were used in the research.

It was observed that LM improves operational performance for manufacturing organizations in developing and developed countries. Small and medium-sized enterprises in both developed and developing countries have difficulties transforming their organizations into lean organizations compared to large enterprises. Furthermore, the review also found that there seems to have been no paper had reported the negative impact of implementing LM in manufacturing industries in developing and developed countries from 2015 to March 2020.

The study used research papers written between January 2015 and March 2020 and only considered manufacturing organizations from developed and developing nations.

The study provides more insight into LM implementation in developing and developed countries. It gives the LM practices and the implications of applying these practices in manufacturing organizations for developing and developed countries.

A preliminary review of papers indicated that this seems to be the first paper that comparatively studies how LM implementation has affected manufacturing organizations in developed and developing countries. The study also assessed the LM practices commonly used by the manufacturing industries in developing and developed countries.