Electron transport layer optimization and parametric sensitivity analysis of α-SrZrS₃ chalcogenide perovskite solar cells: A SCAPS-1D study

Abstract

Perovskite solar cells have rapidly emerged as a leading third-generation photovoltaic technology, driven by their high power-conversion efficiencies and compatibility with low-temperature processing. However, dominant lead–halide perovskite systems continue to face significant challenges related to toxicity and limited operational stability. Scientists are therefore investigating lead-free alternatives, such as the all-inorganic chalcogenide perovskite SrZrS₃. This material has strong optical absorption and has both thermal and chemical stability. Nevertheless, their photovoltaic performance remains constrained by transport-layer selection and interface- and defect-induced recombination losses. Thus, in this work, an ultra-thin all-inorganic SrZrS₃ device with the planar architecture of FTO/ZnO/α-SrZrS₃/NiO_X/Ni has been numerically optimized using SCAPS-1D under AM1.5G illumination (100 mW/cm²) at 300 K. Unlike previous SrZrS₃ simulation studies that primarily focused on transport-layer or contact optimization, the novelty of the present work lies in the development of a comprehensive and defect-sensitive optimization framework that systematically integrates ETL selection, band alignment, interface-defect engineering, resistive-loss analysis, and absorber optimization to provide a more physically realistic assessment of device performance. With NiO_X serving as the hole transport layer, a systematic screening of ETL candidates (ZnO, TiO₂, IGZO, and SnO₂) was conducted. Due to its favorable band alignment and superior device performance, ZnO has been identified as the most suitable ETL. The optimized structure maintains ZnO thickness, α-SrZrS₃ thickness, ZnO donor density, and absorber doping density of 0.08 µm, 0.8 µm, 10¹⁶ cm^-3, and 5 × 10¹⁷ cm^-3 respectively. Keeping the layer defect density at 10¹⁴ cm^-3, interface defect densities at 10¹⁴ cm^-2, series resistance at 3 Ω. cm² and shunt resistance at 5000 Ω. cm², the refined configuration demonstrated an outstanding simulated performance, having V_OC, J_SC, FF, and peak efficiency of 0.997 V, 25.78 mA/cm², 79.16%, and 20.35% respectively. Overall, this study demonstrates that a holistic optimization strategy encompassing systematic ETL selection, defect engineering, and thorough parametric tuning, offers an effective route for the development of high-performance α-SrZrS₃ chalcogenide perovskite solar cells.