Investigation of Zinc Cobaltite (ZnCo₂O₄) as a Hole Transport Layer for Perovskite Solar Cells: Implications for Renewable-Energy Research and Innovation

Abstract

This study investigates Zinc Cobaltite (ZnCo₂O₄) as a potential hole transport layer (HTL) for perovskite solar cells (PSCs) to address the long-term performance degradation observed in conventional HTL materials. Owing to its high stability, wide bandgap, and favorable charge-transport characteristics, ZnCo₂O₄ offers strong potential for efficient carrier extraction and transport in PSC architectures. The HTL plays a critical role in selectively extracting and transferring positive charge carriers (holes) to the anode while maintaining overall device stability. In this work, ZnCo₂O₄-based PSCs were simulated using the GPVDM software, and the Taguchi optimization method was employed to determine the optimal design parameters for achieving maximum power conversion efficiency (PCE). The key parameters considered include HTL thickness, operating temperature, and bandgap energy. Simulation results reveal that a ZnCo₂O₄ thickness of 200 nm yields a PCE of 28.25% using GPVDM. Through Taguchi optimization, the highest PCE of 32.23% was achieved with an optimized configuration comprising a 300 nm ZnCo₂O₄ layer, 300 K temperature, 2.0 eV bandgap, and mobility factors of 9.14 × 10⁻⁶ cm² V⁻¹ s⁻¹ for both electrons and holes. These findings demonstrate that ZnCo₂O₄ is a promising HTL candidate for high-efficiency and thermally stable PSCs. Further experimental validation and interface engineering could enhance its performance and enable its integration into next-generation perovskite photovoltaic devices.