Enhancement of the environmental stability of perovskite thin films via AZ5214-photoresist and PMMA coatings

This study presents a novel investigation into enhancing the environmental stability of perovskite thin films, specifically focusing on the effects of AZ5214 photoresist compared to the widely studied PMMA. By employing advanced matrix encapsulation techniques, we aim to stabilize methylammonium lead iodide (MAPbI 3 ) and methylammonium lead bromide (MAPbBr 3 ) films, which are meticulously prepared via a two-step solution deposition method under controlled ambient conditions. Our approach involves spin-coating layers of poly(methyl methacrylate) (PMMA) and AZ5214 photoresist to singularly encapsulate the perovskite films. This encapsulation provides a robust hydrophobic barrier, significantly mitigating moisture ingress and addressing pinhole challenges within the perovskite structure. Through comprehensive characterizations—including scanning electron microscopy (SEM), X-ray diffraction (XRD), and photoluminescence (PL) spectroscopy—we demonstrate that AZ5214 photoresist, despite being thicker than PMMA, offers significantly enhanced stability. Our study revealed that coating MAPbI 3 perovskite with a 127-nanometer layer of PMMA resulted in a PL intensity retention of 44.8% after 40 days, which is a 589.23% improvement over the uncoated perovskite. Similarly, a 1200-nanometer layer of AZ5214 photoresist achieved a PL intensity retention of 38.2%, reflecting a 487.69% enhancement. For MAPbBr 3 perovskite, the PMMA coating achieved a PL intensity retention of 43.1%, a 71.72% improvement, while the AZ5214 photoresist coating resulted in a retention of 48.4%, showing a 92.83% enhancement. These findings highlight the superior stability provided by AZ5214 photoresist, especially for MAPbBr 3 , making it a more effective barrier against environmental degradation compared to PMMA.