Abstract
This study sought to optimize the structures in a working electrode at the micro-as well as electron-scales with the aim of suspending electron-hole recombination in order to increase the power conversion efficiency of dye-sensitized solar cells (DSSCs). Based on a review of the literature and basic theory of electrical physics, we were able to establish a linear relationship between open-circuit photovoltage (V-oc) and fill factor (FF), which led to the formulation of two equations: one of which relates FF directly to series resistance (r(s)) and the other relates FF to shunt resistance (r(sh)). This led to the formulation of a new DSSC design strategy with the aim of increasing Voc of the DSSC by reducing rh (part of r(s)) as well as increasing r(sh). The proposed design strategy is based on the fabrication of a multilayer TiO2 microstructure in conjunction with electron orbital hybridization. This strategy was implemented using fifteen sets of experiments aimed at simultaneously optimizing structures in working electrodes at the micro-and electron-scales. The resulting design rules and mechanisms underlying carrier transport provide practical guidance and critical knowledge required for the further development of next generation photo electron devices. (C) 2015 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.