A new study Sun et al. introduces the Flexible Photovoltaic Fatigue Factor (F) — a novel figure of merit designed to quantify the mechanical durability of flexible solar cells under repeated bending. The metric condenses the operational power conversion efficiency decay ΔPCE of device performance over bending cycles at a given strain, providing a simple yet powerful tool for comparing mechanical stability across technologies.

In this framework, ΔPCE captures the photovoltaic performance change, while ε (strain) summarizes the mechanical stress applied during the bending test.

The authors emphasize the importance of standardized reporting for mechanical testing — including parameters such as substrate thickness (ts), bending radius (R), strain (ε), number of bending cycles (NBC), PCEinitial, and PCEfinal. Following the protocol proposed by Fukuda et al., these best practices aim to enhance consistency and reproducibility across flexible PV research.

Beyond current flexible architectures, the study anticipates that future non-rigid photovoltaic devices may require adapted or new figures of merit to capture more complex mechanical behaviors — marking the beginning of a more robust, quantitative framework for mechanical stability in emerging photovoltaics.