Mechanistic origin and unlocking of negative capacitance in perovskites solar cells

Mohd Taukeer Khan; Peng Huang; Abdullah Almohammedi; Samrana Kazim; Shahzada Ahmad

doi:10.1016/j.isci.2020.102024

Mechanistic origin and unlocking of negative capacitance in perovskites solar cells

iScience. 2020 Dec 31;24(2):102024. doi: 10.1016/j.isci.2020.102024. eCollection 2021 Feb 19.

Authors

Mohd Taukeer Khan^{1

2}, Peng Huang¹, Abdullah Almohammedi², Samrana Kazim^{1

3}, Shahzada Ahmad^{1

3}

Affiliations

¹ BCMaterials, Basque Center for Materials, Applications and Nanostructures, UPV/EHU Science Park, 48940 Leioa, Spain.
² Department of Physics, Faculty of Science, Islamic University of Madinah, Prince Naifbin Abdulaziz, Al Jamiah, Madinah 42351, Kingdom of Saudi Arabia.
³ IKERBASQUE, Basque Foundation for Science, 48009 Bilbao, Spain.

Abstract

We have unlocked the mechanistic behavior of negative capacitance in perovskite solar cells (PSCs) by analyzing impedance spectra at variable photovoltage and applied bias, temperature-dependent capacitance versus frequency (C-f) spectra, and current-voltage (J-V) characteristics. We noted that p-i-n type PSCs having PEDOT:PSS or PTAA as hole transport layer display negative capacitance feature at low and intermediate frequencies. The activation energies (E _a ) for the observance of negative capacitance were found to be in a similar order of magnitude required for the ionic migration. Moreover, the kinetic relaxation time (τ _kin ) estimated to be in the same order of magnitude required to activate the halide ion migration. Our investigation suggests that the primary reason for the appearance of negative capacitance in PSCs with a p-i-n configuration is associated with the migration of halide ions and vacancies in the perovskite layers.

Keywords: Devices; Energy Materials; Energy Resources; Energy Systems.