Development of gallium doped zinc oxide as electron transport layer for perovskite solar cell

Abstract

Perovskite solar cells (PSCs) have emerged as a leading photovoltaic technology owing to the remarkable electrical and physical properties exhibited by perovskite-structured compounds. This study focuses on the exploration of gallium-doped zinc oxide (GZO) as a promising replacement for traditional electron transport layers (ETLs), such as titanium dioxide (TiO2) and tin dioxide (SnO2), which come with inherent drawbacks. The investigation involves numerical simulations, thin film deposition through sputtering, and comprehensive characterizations to achieve the research objectives. Utilizing SCAPS-1D simulation software, the feasibility of GZO as an ETL in PSCs is verified, demonstrating a simulated power conversion efficiency (PCE) of 18.43%. During the sputtering process, careful investigation is conducted on the effects of sputtering power, argon (Ar) gas flow, and deposition time. Comprehensive characterizations, including X-ray diffraction, field emission scanning electron microscopy (FESEM), ultraviolet-visible spectroscopy (UV-vis), and hall measurements, provide insights into the structural, morphological, optical, and electrical properties of the deposited films. Optimized conditions, obtained by maintaining RF power at 70W with 3 sccm argon flow during a 50-minute deposition, exhibit favourable properties such as lower resistivity (4.85×10-3 Ω-cm), higher carrier concentration (6.52×1019 cm-3), and optical transmittance (~85%). These optimized parameters are then applied to fabricate n-i-p PSCs without interface engineering, resulting in a PCE of 4.34%. Though this efficiency level is comparatively low, it underscores the viability of radio frequency sputtered GZO thin films as an ETL in PSCs. Further enhancements through interface engineering, surface texturing, and additional optimization steps are suggested for future efficiency improvements. This research holds significance as it marks the first incorporation of GZO film as an ETL in Cs-based perovskite solar cells. Additionally, it introduces the novel use of GZO as an ETL deposited via radio frequency sputtering, paving the way for advanced engineering strategies to enhance perovskite solar cell efficiency.