PGMEA-based interlayer engineering for thermally stable and efficient perovskite solar cells

Abstract

Wide-bandgap CsFAMAPbI1-xBrx perovskites have emerged as a pivotal focus in photovoltaic due to their exceptional light-harvesting capabilities and tunable bandgaps. However, the rapid degradation of photoelectric performance and compromised long-term stability- triggered by interfacial defects, high-temperature phase transitions, and ion migration-remain significant challenges. In this study, a Poly (methyl methacrylate) (PMMA) interlayer was engineered using propylene glycol methyl ether acetate (PGMEA) as a functional solvent. The PGMEA-mediated spin-coating enabled the uniform deposition of PMMA between the perovskite absorber and the hole transport layer (spiro-OMeTAD). The regulatory mechanisms of this interlayer on device performance and thermal stability were systematically investigated. Mechanistic investigations reveal that PGMEA, owing to its optimal boiling point and polarity, promotes the formation of a highly homogeneous PMMA film. This functional interlayer effectively passivates grain boundaries and interfacial defects while concurrently bolstering film crystallinity and hydrophobicity. Following thermal annealing at 150 °C for 3 h, the power conversion efficiency reached 19.37%. Furthermore, the unencapsulated devices maintained 91.5% of their initial efficiency after 800 h of aging, demonstrating a robust interfacial engineering strategy for high-performance wide-bandgap perovskite solar cells.