New fabrication process of long-life dye-sensitized solar cells by in situ gelation of quasi-solid polymer electrolytes

Leakage of liquid electrolyte and damage to dye-sensitized solar devices due to ultraviolet irradiation typically result in the poor long-term stability of liquid-electrolyte-based dye-sensitized solar cells (DSSCs). In this study, a simple in situ gelation (ISG) process is developed for the quasi-solid-state electrolyte (QSE) in DSSCs using polyvinyl butyral (PVB), a polymer used worldwide in laminated glass. The diffusion coefficients and ionic conductivities of the QSEs are analyzed, and the optimal ionic conductivity is found to be approximately 2.64 x 10(-3) S cm(-1), which is approximately six orders of magnitude higher than that of the original PVB thin film. The ISG-QSE devices exhibit a high conversion efficiency of 4.86% at 100 mW cm(-2): this is approximately 98% of the efficiency of corresponding liquid electrolyte (LSE) cells. Moreover, the devices can maintain a remarkable 98% of their original efficiency after 2100 working hours owing to the addition of 5% UV absorber to the ISG electrolyte. In addition, the ISG-electrolyte-based DSSCs can drive a 5 x 5 cm(2) electrochromic (EC) device, demonstrating the potential for the application of this combination in smart windows in the future. (C) 2013 Elsevier B.V. All rights reserved.