Improving Charge Transport in Organic Photovoltaics From Phase Separation to Nanogaps.

摘要

Organic photovoltaics (OPVs) are being engineered to meet the demand for affordable renewable energy but their efficiency and lifetime need to be improved for widespread commercialization. The chapters within this dissertation each describe a project designed to optimize OPVs from a variety of approaches: new materials, processing and characterization, and novel device architectures. Charge transport is emphasized in bulk heterojunction blend solar cells. The evolution of the electronic properties with solvent vapor annealing is studied in polyflourene-copolymer and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) blended OPVs using various scanning probe techniques. The photovoltaic properties of eleven donor-acceptor organometallic copolymers with PCBM are determined and related to the strength of the intramolecular charge transfer interactions in the organometallic copolymers. Nanostructured electrode devices are lastly introduced as a route to increase OPV efficiency, and charge extraction by a linearly increasing voltage is used to measure the charge transport properties of poly(3-hexylthiophene):PCBM in nanogaps.