Verification of necessity of one-dimensional titania nanoscale materials for dye-senskized solar cells

摘要

Necessity of highly crystallized 1-dimensional titania nanoscale materials (1DTNM) was elucidated by theoretical consideration based on both the electron transfer processes shown by Nyquist plots obtained in electrochemical impedance spectroscopy (EIS) and current-voltage (I-V) measurements. The consideration was verified by systematic experiments, in which titania nanowires (TNWs) with network structure were chosen as a highly crystallized 1DTNM. The cells with electrodes made of various TNW content from 0% to 100% of TNWs mixed with P-25 were fabricated. Based on the measurements of I-V relationship and EIS measurements of these cells, the following three points were clearly demonstrated as verification of the consideration; 1) resistance of electron transport in the titania electrode to the conducting glass electrode is small, 2) the ratio of the resistance for the recombination reactions against that for the transport rate to the conducting glass electrode is large, i.e., efficiency of electron collection is high, and 3) electron density in the titania electrode is high. These points are essentially important to realize high efficiency in DSSCs.