폴리아크릴로나이트릴/실리카 복합 전기방사 막을 이용한 염료감응 태양전지 광전특성 연구

Abstract

Dye-sensitized solar cell (DSSC) has been considered as an alternative to a conventional silicon solar cell because of low cost, easy fabrication and relatively high conversion efficiency. Recently, an impressive conversion efficiency of 12 % has been achieved in a DSSC with a liquid electrolyte. However, leakage or evaporation of liquid electrolyte is a critical problem that limits the long-term operation and practical use of DSSCs. To overcome these problems, considerable efforts have been made to replace liquid electrolytes with gel polymer electrolytes that exhibit high ionic conductivity and improved stability. Unfortunately, such gel polymer electrolyte suffers from poor mechanical strength. An activation of a porous polymer membrane in electrolyte solution is an efficient method to solve this problem. Unlike conventional methods such as solution casting and direct dissolution of the polymer in the electrolyte solution, this procedure handles the mechanically robust porous membrane until adding liquid electrolyte to it at last. In this work, we prepared polyacrylonitrile (PAN) nanocomposite fibrous membrane containing different amount of SiO2 nanoparticles which have been obtained via electrospinning. The DSSC was then assembled by sandwiching the electrospun membrane between dye-coated TiO2 electrode and Pt counter electrode, and injecting an electrolyte solution into the cell. It is well known that the SiO2 filler can improve the ionic conductivity of the composites by introducing Lewis acid-base interactions between the polar surface groups of the inorganic filler and the electrolyte ionic species. The results of scanning electron microscopy (SEM), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) indicate that the addition of SiO2 nonaoparticles affects the structure and properties of the fibrous membrane. The membranes have three-dimensional and fully interconnected network structures, which are combined with homogeneous distribution of SiO2 nanoparticles. The PAN/SiO2 (10 wt.%) nanocomposite fibrous membrane electrolytes which was composed of 0.5 M lithium iodide, 0.05 M I2 and 0.5 M 4-tert-butylpyridine in acetonitrile has the ionic conductivity of 2.72 mS cm-1 at room temperature. The DSSC based PAN/SiO2 (10 wt.%) nanocomposite fibrous membrane electrolytes was observed to possess a much higher conversion efficiency (CE=7.85 %) than the other nanocomposite fibrous membrane electrolytes DSSC at 100 mW cm−2. The overall nanocomposite fibrous membrane electrolytes DSSCs exhibited more than 98 % of initial efficiency after 14 days at room temperature.