New Frontiers for Solar Cells and Light Emitting Devices

Abstract

Solar energy, with its abundance and availability, would ultimately replace dwindling fossil fuel reserves in this new era of cleaner and more efficient energy as the world surges on to new technologies and horizons. This research investigates new frontiers for solar cells and light emitting devices: from organic solar cells and light emitting devices to policy. The effects of bending on the electrical, optical, structural and mechanical properties of flexible organic photovoltaic (OPV) cells were explored first. Bulk heterojunction organic solar cells were fabricated on Polyethylene terephthalate (PET) substrates using Poly-3-hexylthiophene: [6, 6]-phenyl-C61-butyric acid methyl ester (P3HT: PCBM) as the active layer and Poly (3, 4- ethylenedioxythiophene) Polystyrenesulfonate (PEDOT: PSS) as the hole injection layer. All the organic layers were deposited by the method of spin coating while the Al cathode was vacuum thermally evaporated. Electrical, optical and deformation characteristics were measured as layers were deposited. The relationship between the optoelectronic performance of the various device layers and the applied mechanical strains were analyzed. The effects of stress and strain on the current-voltage characteristics of the device and its failure were modeled using finite element analysis. With this knowledge that bending strains affect the optoelectronic and failure mechanisms in bendable/ flexible OPVs, a year-long survey assessment was conducted on a rural off-grid community in central Kenya to determine the different factors that affected the adoption of solar lanterns in the community. Impact on the people’s socio-economic, health, and education levels were also assessed. The lanterns were shown to have a 96% adoption rate in the sample community and this resulted in a 14.7% drop in annual lighting-related expenditures.