Building lithium fluoride nanoparticle films for organic photovoltaics

Official URL: http://192.168.1.20/record=b1305917 (Table of Contents)

Organic solar cells are primarily composed of conjugated carbon based materials which are actively involved in light absorption and charge transfer. Although organic photovoltaics have advantages such as long time stability, cheapness and easy processibility with comparison to their inorganic competitors, due to its low conversion efficiency (5-6%) there is still a need for research to commercialize these devices. Lithium fluoride is commonly used to enhance conversion efficiency and charge injection at electrode bilayers in organic electronics. However, the conventional processing of lithium fluoride typically requires high vacuum methods, such as thermal evaporation. This thesis focuses on the development of an ambient, solution processable alternative, in which polymeric reverse micelle reactors are used to synthesize lithium fluoride particles. Apart from controlling the synthesis of lithium fluoride nanoparticles, micelles has a role in the deposition of nanoparticles into a well-ordered, two dimensional layer during spin coating on the donor substrate. The formation of lithium fluoride particles inside micelles were proved by electron and x-ray diffraction measurements. To assess the performance of the solution-processed lithium fluoride, inverted device fabrication and comparative work function measurements were carried out together with thermal evaporated lithium fluoride. Both results support the suitability of solution-processed lithium fluoride for electrode bilayers in organic solar cells. Additionally, different nano transfer printing studies were carried out to integrate solution processed lithium fluoride particles to organic devices and further studies are needed to achieve complete transfer.