Failure mechanism for flexible dye-sensitized solar cells under repeated outward bending: Cracking and spalling off of nano-porous titanium dioxide film

• Published in: Journal of power sources Vol. 280; pp. 182 - 189
• Main Authors: He, Xue-Long, Yang, Guan-Jun, Li, Chang-Jiu, Liu, Mei, Fan, Sheng-Qiang
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.04.2015
• Subjects: Bending; Differential scanning calorimetry; Dye-sensitized solar cells; Electrochemical impedance spectroscopy; Failure mechanism; Failure mechanisms; Fracture mechanics; Outward bending; Photovoltaic cells; Solar cells; Spalling; Titanium dioxide; Failure mechanism; Dye-sensitized solar cells; Electrochemical impedance spectroscopy; Outward bending
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2015.01.088

Flexibility, as well as efficiency, of flexible dye-sensitized solar cells (DSCs) is of significant importance to their applications. In this study, quantitative bending test, carried out with a lab-developed solar cell bending tester, is used to simulate the flexible service condition. The photovoltaic performance, morphology of the photoanode and electrochemical property evolution during bending service are examined to aim at understanding the bending failure mechanism for the flexible DSCs under repeated outward bending (the TiO2 film in the photoanode is in tension). Results show that when the bending radius is 12 mm, the efficiency of the plastic DSCs keeps unchanged with increasing the bending cycle. When the bending radius is smaller than 12 mm, the efficiency of the flexible DSCs decreases with increasing the bending cycle. The electrochemical impedance spectroscopy results show that the increase of the electron transport resistance (Rt) in TiO2 network is responsible for the degradation of efficiency. Furthermore, the photoanodes after repeated bending is cracking and spalling off from the ITO surface. Finally, a failure model for the flexible DSCs under repeated outward bending is proposed. [Display omitted] •Performance of solar cell under multiple outward bending was systematically studied.•Cracking and spalling off of TiO2 film are responsible for failure of solar cell.•A failure model for flexible DSCs under repeated outward bending was proposed.