Multi stress testing of OPV modules for accurate predictive ageing and reliability predictions

OPV degradation remains a complex challenge and previous studies have been shown the degradation to be a function of multiple stresses, so it can be inaccurate to predict failure rates using single stress tests. In this paper, a new testing methodology whereby multiple stresses are applied simultaneously using a ‘design of experiment (DOE) approach’ is reported and used for predictive ageing of modules. A multi-stress data is used for predictive ageing of OPV modules under different stress levels; a General-Log-Linear (GLL) life model has been adapted and applied in order to predict the life of OPV modules and this is compared to experimental data, which shows that a close estimation of simulated lifetime is obtained (within 18% accuracy). The life test models can be used for predicting ageing of OPV modules in different geographic locations and could be used to account for different degradation rates due to seasonal climatic variations. Furthermore, by using the DOE data, we show how the major stress factors can be screened and their statistical significance upon degradation quantified using ANOVA. One of the potential benefits of using this approach for OPV degradation studies is that additional factors could be added to study the impact on degradation to provide a more comprehensive study.