Low-Temperature-Processed Flexible Perovskite Solar Cells: Performance Analysis and Stability Dynamics

Flexible perovskite solar cells (fPSCs) are considered promising for wearable and portable photovoltaic applications; however, their operational stability under mechanical stress remains a significant challenge. In this study, the degradation pathways of low-temperature-processed fPSCs fabricated on polyethylene terephthalate (PET)/ITO substrates using a SnO 2 /MAPbI 3 /Spiro-OMeTAD/Au architecture were comprehensively examined. Controlled mechanical fatigue was applied using a bending radius of ∼11.3 mm for more than 300 cycles. A 24% increase in root-mean-square (RMS) surface roughness, along with elevated Urbach energy and trap density, was observed through microstructural analysis, indicating an enhanced electronic disorder caused by strain. Electrical properties were evaluated using capacitance–voltage (CV), capacitance–frequency (CF), impedance spectroscopy, and electroluminescence (EL) imaging, through which significant performance deterioration was identified. A more than 60% decline in external EL quantum efficiency, as well as increased series resistance ( R s ), charge transport resistance ( R ct ), and hysteresis index, were recorded after cycling. The evolution of capacitance behavior and CV hysteresis under both dark and illuminated conditions was attributed to strain-induced ion migration and interface degradation. Under reverse bias, persistent thermal hot spots were detected using infrared thermography, indicating local heating effects resulting from interfacial delamination. These insights are expected to inform the design of mechanically durable, ion-stable perovskite architectures for next-generation flexible photovoltaic technologies.