Fast-Switching Photovoltachromic Cells with Tunable Transmittance

• Published in: ACS nano 2009-08, Vol.3 (8), p.2297-2303
• Main Authors: Wu, Jih-Jen, Hsieh, Min-Da, Liao, Wen-Pin, Wu, Wei-Ting, Chen, Jen-Sue
• Format: Article
• Language: English
• ISSN: 1936-0851; 1936-086X
• DOI: 10.1021/nn900428s

In this study, we demonstrate a photovoltachromic cell (PVCC) which is a solar cell and able to take solar energy to stimulate chromic behavior with the characteristic of tunable transmittance. The cell is composed of a patterned WO3/Pt electrochromic electrode and a dye-sensitized TiO2 nanoparticle photoanode. Compared to reported photoelectrochromic cells (PECC) with nonpatterned WO3 electrochromic electrodes, PVCC achieves a much faster bleaching time of only 60 s by blocking the light at short circuit. When PVCC is bleached under illumination at open circuit, an exceedingly short bleaching time of 4 s is achieved. Furthermore, PVCC has photovoltaic characteristics comparable to those of dye-sensitized solar cells (with Pt as the counter-electrode). In contrast to conventional photochromic devices, the transmittance of PVCC under a constant illumination can be adjusted by the resistance of a load in series with the cell. These characteristics are a result of the patterned WO3/Pt electrode, which provides effective charge transfer pathways to facilitate the charging/discharging of Li ions and electrons via the photovoltaic potential and the Pt-electrolyte catalytic route, respectively.