An intrinsic electrical conductivity study of perovskite powders MAPbX3 (X = I, Br, Cl) to investigate its effect on their photovoltaic performance

Abstract

An investigation into the intrinsic electrical conductivity of perovskite powders MAPbX₃, where X represents iodine (I), bromine (Br), or chlorine (Cl), was conducted to explore its impact on their photovoltaic performance. Results revealed that MAPbCl₃ demonstrated light absorption ability in the ultraviolet and visible regions, while MAPbBr₃ showed capacity for light absorption at longer wavelengths in the visible spectrum. On the other hand, MAPbI₃ exhibited good absorption at longer wavelengths, indicating its ability to absorb light in the near-infrared region. The optical bandgap of each perovskite was determined to be 2.90 eV for MAPbCl₃, 2.20 eV for MAPbBr₃, and 1.47 eV for MAPbI₃. The electrical conductivities of these powders were measured in-plane using the four-probe method and through-plane by electrochemical impedance spectroscopy (EIS). Electrochemical impedance spectroscopy (EIS) studies revealed a significant change in the conductivity of the MAPbI₃ perovskite at temperatures between 80 °C and 100 °C. This change could be attributed to structural modifications induced when the temperature exceeds these values. The through-plane conductivity changed from 3 × 10⁻⁸ S cm⁻¹ at 60 °C to approximately 6 × 10⁻⁵ S cm⁻¹ at 120 °C and around 2 × 10⁻³ S cm⁻¹ at 200 °C. Meanwhile, the sheet conductivity (in-plane conductivity) measurements performed at ambient temperature reveal that sheet conductivities are 489 × 10³ S m⁻¹, 486 × 10³ S m⁻¹ and 510 × 10³ S m⁻¹ for MAPbBr₃, MAPbCl₃ and MAPbI₃, respectively. This study provides valuable insights for optimizing the performance of perovskite solar cells. Understanding how dopants influence the electrical conductivity and photovoltaic properties of the perovskite material, this work will enable researchers to design and engineer more efficient and stable solar cell devices based on MAPbX₃ perovskites.