ZnO-treated TiO2 inverse opal electrodes for dye-sensitized solar cells

• Published in: Current applied physics 2013, 13(5), , pp.841-845
• Main Authors: Kim, Hye-Na, Moon, Jun Hyuk
• Format: Article
• Language: English
• Subjects: coatings; Dye-sensitized solar cells; Electrodes; energy conversion; energy-dispersive X-ray analysis; Inverse; Inverse opals; opal; Photovoltaic cells; Porous electrodes; Solar cells; spectroscopy; TiO2; Titanium dioxide; Volatile organic compounds; X-radiation; Zinc; Zinc oxide; ZnO; 물리학
• ISSN: 1567-1739; 1878-1675
• DOI: 10.1016/j.cap.2012.12.014

We report that the photovoltaic properties of inverse opal TiO2 (io-TiO2) electrodes in dye-sensitized solar cells can be enhanced by ZnO treatment of the inverse opal structures. ZnO was coated on the surface of io-TiO2 via the sol–gel reaction of ZnO precursors. Energy dispersive X-ray spectroscopy (EDX) measurements showed that the amount of ZnO on the io-TiO2 surface was measured to be 0.12–0.50 wt% of zinc, depending on the number of coatings. Compared to bare inverse opal electrodes, the energy conversion efficiency of cells increased for the 0.35 wt% ZnO-coated electrodes, and then decreased for the 0.50 wt% ZnO-coated electrodes. The maximum efficiency of 5.3% was achieved, corresponding to a 23% increase in efficiency compared with bare io-TiO2 electrodes. The enhanced efficiency was mainly attributed to the improvement of the open-circuit voltage (VOC). EIS and dark current measurements confirmed that this enhancement in VOC was due to the movement of the conduction band edge in a negative direction after ZnO treatment, rather than the formation of a barrier layer for electron recombination. ► ZnO-treated TiO2 inverse opals were fabricated for the use of electrodes in DSSC. ► A multiple coating of ZnO precursors was applied to control the coating quantity. ► The effect of ZnO quantity on photovoltaic parameters was investigated. ► ZnO treatment enhanced VOC by shifting the conduction band edge of TiO2.