AE Characterization of damage in flexible solar cells under torsional loading

Abstract

Torsional tests of flexible solar cells were conducted to evaluate the electrical performance degradation caused by mechanical loading. To elucidate the degradation mechanism of solar cells, it is indispensable to detect the damage initiation and accumulation due to the applied mechanical loading and to identify which of the damage contributes to the electrical performance degradation. Therefore, the AE technique was used to monitor the damage initiation and accumulation process, and the LT method, which can detect the temperature modulation caused by leakage current generation, was used to identify the damage that contributes to performance degradation. It was shown from AE measurement that damage which is a precursor of electrical performance degradation were detected. It was also found that the damage caused by tensile stress, which was dominant at the specimen ends, contributes the initiation of performance degradation. In addition, damage caused by the principal stress near the center of the specimen, which is inclined at 45° to the specimen length direction, was also suggested to cause significant performance degradation. Consequently, it was demonstrated that the electrical performance degradation processes of flexible solar cells under torsional loading.