Е-Публикации
Технически университет - София

Abstract: This study examines sputtered strontium titanate SrTiO₃ as a piezoelectric electron-transport layer (ETL) in flexible perovskite solar cells and evaluates how its thickness and defect chemistry influence device efficiency and operational stability. Particular attention is given to the combined role of piezoelectric polarization and oxygen-vacancy engineering in SrTiO₃, since both factors can modify interfacial band alignment and facilitate electron extraction from the absorber layer. SrTiO₃ layers with thicknesses between 0 and 30 nm were incorporated into the device stack in order to determine the thickness range that maximizes the open-circuit voltage Voc, the short-circuit current density Jsc, and the power conversion efficiency PCE. Device performance improved only up to an intermediate SrTiO₃ thickness, whereas thicker films introduced additional transport resistance and limited charge collection across the ETL/absorber interface. Among the investigated structures, the best-performing devices contained an SrTiO₃ layer of about 20 nm, for which the measured power conversion efficiency reached 12.4%. Stability measurements further indicate that the SrTiO₃ interlayer contributes to device robustness, with the optimized cells retaining about 80% of their initial efficiency after 1,000 bending cycles and 77% after heating at 70 °C.

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