Enhancing charge extraction in perovskite solar cells using a MnSe electron transport layer for enhanced efficiency via conduction band engineering

Abstract

Recombination losses in perovskite solar cells (PSCs) remain a persistent challenge, limiting both their efficiency and stability. Developing an effective electron transport layer (ETL) is crucial for improving charge extraction and minimizing energy losses. This study introduces manganese selenide (MnSe) as a novel ETL between titanium dioxide (TiO₂) and methylammonium lead iodide (MAPbI₃) to reduce recombination losses and enhance the performance of PSC. X-ray diffraction (XRD) analysis confirms the cubic crystal structure of MnSe. Ultraviolet-visible (UV-Vis) spectroscopy reveals that the energy bandgap (E_g) of MnSe is 2.06 eV, which lies between the E_g values of MAPbI₃ and TiO₂, suggesting ideal conduction band (CB) alignment for efficient electron extraction. Raman spectroscopy verifies the structural integrity and phase purity of MnSe and the perovskite. Photoluminescence (PL) studies demonstrate reduced non-radiative recombination, confirming the improved charge transfer. Electrochemical impedance spectroscopy (EIS) indicates a higher recombination resistance (R_rec) of 3791 Ω for an FTO\TiO₂\MnSe-based device as compared to FTO\TiO₂, leading to suppressed charge losses. Current density–voltage (J–V) analysis shows an enhanced power conversion efficiency (PCE) of 22.63% with a fill factor (FF) of 0.802 for the FTO\TiO₂\MnSe-based device. This research suggests that future work will focus on the large-scale fabrication of MnSe-based ETLs.