Abstract
In this study, tensile tests of indium tin oxide (ITO) deposited on polyethylene naphthalate (PEN) films (ITO + PEN films) used in dye-sensitized solar cells (DSCs) were carried out. ITO + PEN films are fabricated at 150℃. Therefore, to clarify the influence of heat treatment on mechanical properties of ITO + PEN, the specimens with heat treatment were prepared. In order to discriminate AE signals in ITO from PEN films, PEN film specimens (ITO was removed by 17.5% hydrochloric acid) were also prepared. It was found from tensile tests that many AE signals were detected in ITO + PEN films, while few AE signals were detected in PEN films. On the other hand, the electric resistance of ITO was also measured during tensile tests. These results suggested that the critical damage in ITO was detected by the AE measurement more sensitively than the electric resistance. To identify AE sources, in-situ observation of specimen during tensile test with AE measurement was carried out. It was emphasized that AE behavior shows good agreement with the cracking behavior in ITO. Damages in ITO under mechanical strain were successfully monitored by AE technique in the present study. Consequently, it was suggested that AE technique could be a powerful technique for evaluating the damage accumulation process in DSCs.
