Light intensity modulated impedance spectroscopy (LIMIS) in all-solid-state solar cells at open-circuit. (September 2020)

• Record Type: Journal Article
• Authors: Almora, Osbel; Zhao, Yicheng; Du, Xiaoyan; Heumueller, Thomas; Matt, Gebhard J.; Garcia-Belmonte, Germà; Brabec, Christoph J.
• Is Part Of: Nano energy. Volume 75(2020)
• Publication Date: 2020-09
• Subjects: Impedance spectroscopy -- Solar cells -- Light intensity modulation -- Photocurrent -- Charge carrier generation rate -- Perovskites; Nanoscience -- Periodicals; Nanotechnology -- Periodicals; Nanostructured materials -- Periodicals; Power resources -- Technological innovations -- Periodicals; Nanoscience; Nanostructured materials; Nanotechnology; Power resources -- Technological innovations; Periodicals; 621.042
• DOI: 10.1016/j.nanoen.2020.104982
• Languages: English
• ISSNs: 2211-2855

Abstract

Abstract: Potentiostatic impedance spectroscopy (IS) is a well-established characterization technique for elucidating the electric resistivity and capacitive features of materials and devices. For solar cells, by applying a small voltage perturbation the current signal is recorded and the recombination processes and defect distributions can be accessed. In this work, a photo-impedance approach, named "light intensity modulated impedance spectroscopy" (LIMIS), is first time tested in all-solid-state photovoltaics by individually recording photocurrent (IMPS) and photovoltage (IMVS) responsivity signals due to a small light perturbation at open-circuit (OC), and combining them: LIMIS = IMVS/IMPS. The experimental LIMIS spectra from silicon, organic, and perovskite solar cells are presented and compared with IS. Our theoretical analyses, including equivalent circuit models, show a correction to the lifetimes values by obtaining the total differential resistances and capacitances combining IS and LIMIS. This correction addresses some discrepancies among different techniques, as also shown with photo-induced transient photovoltage. The experimental differences between IS and LIMIS proves the unsuitability of the superposition principle and suggest a bias-dependent photo-current correction to the empirical Shockley equation of the steady-state current at different illumination intensities around OC. In addition, new features are reported for the low-frequency capacitance of perovskite solar cells. Graphical abstract: Image 1 Highlights: LIMIS combines IMPS and IMVS in solar cells at open-circuit for a novel photoimpedance spectroscopy approach. LIMIS versus IS results a perspective tool for discerning bulk/interface recombination phenomena. Photo-capacitance/-resistance new approaches correct estimation of charge carrier lifetime. Bias dependent photocurrent is included in charge carrier collection parametrization.