The Origin of Photoinduced Capacitance in Perovskite Solar Cells: Beyond Ionic‐to‐Electronic Current Amplification

Choi, Wookjin; Song, Sung Won; Han, Se Gyo; Cho, Kilwon

doi:10.1002/aelm.202000030

Cited by 11 publications

(18 citation statements)

References 47 publications

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“…In other cases, the impedance spectra show the formation of an intermediate frequency loop between the LF and HF arcs, Figure c. ,− This has been observed for systems where charge extraction contact is not efficient (i.e., Nb 2 O 5 ) and in samples with composite contacts. , Similar results are observed for TiO 2 prepared by spray pyrolysis . The TiO 2 layer has an influence on the impedance spectroscopy response of the cells over the whole frequency range.…”

Section: Negative Capacitance Phenomenasupporting

confidence: 60%

Impedance Spectroscopy of Metal Halide Perovskite Solar Cells from the Perspective of Equivalent Circuits

2021

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Impedance spectroscopy (IS) provides a detailed understanding of the dynamic phenomena underlying the operation of photovoltaic and optoelectronic devices.Here we provide a broad summary of the application of IS to metal halide perovskite materials, solar cells, electrooptic and memory devices. IS has been widely used to characterize perovskite solar cells, but the variability of samples and the presence of coupled ionic-electronic effects form a complex problem that has not been fully solved yet. We summarize the understanding that has been obtained so far, the basic methods and models, as well as the challenging points still present in this research field. Our approach emphasizes the importance of the equivalent circuit for monitoring the parameters that describe the response and providing a physical interpretation. We discuss the possibilities of models from the general perspective of solar cell behavior, and we describe the specific aspects and properties of the metal halide perovskites. We analyze the impact of the ionic effects and the memory effects, and we describe the combination of light-modulated techniques such as intensity modulated photocurrent spectroscopy (IMPS) for obtaining more detailed information in complex cases. The transformation of the frequency to time domain is discussed for the consistent interpretation of time transient techniques and the prediction of features of current−voltage hysteresis. We discuss in detail the stability issues and the occurrence of transformations of the sample coupled to the measurements.

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Section: Negative Capacitance Phenomenasupporting

confidence: 60%

Impedance Spectroscopy of Metal Halide Perovskite Solar Cells from the Perspective of Equivalent Circuits

2021

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“…The second capacitance, C acc , labels the ionic migration and accumulation at the perovskite/ETL interface under short circuit condition and in the presence of external fields, respectively. The C acc with R 2 (related to recombination resistance) accounts for the low-frequency arc ( Choi et al., 2020 ; Anaya et al., 2017 ; Khan et al., 2020 , 2019 ). Ionic capacitance values in type A and type B devices under short circuit condition and dark were extracted to be 8.76 × 10 −7 and 3.92 × 10 −8 F, respectively; this value increased by an order of magnitude under light illumination.…”

Section: Resultsmentioning

confidence: 99%

“…Inductive loop or negative capacitance is not limited to a specific device configuration and reported for both types of devices ( n-i-p or p-i-n ) ( Ebadi et al., 2014 ; Guerrero et al., 2016 ), with or without charge-selective contacts ( Choi et al., 2020 ; Feng et al., 2018 and Ghahremanirad et al., 2017 ); moreover, it was also noted in MAPbBr 3 single crystal ( Kovalenko et al., 2017 ). Thus, inductive loop and negative capacitance in PSCs are unrelated to the grain-boundary defects or interfacial phenomenon; rather they are intrinsic properties of perovskite material itself.…”

Section: Introductionmentioning

confidence: 91%

“…found that the negative capacitance and inverted J-V hysteresis in PSC's features stemmed from the same origin, i.e., large kinetic relaxation times because of an increased recombination value ( Alvarez et al., 2020 ). The correlation for the ionic-to-electronic current amplification for the observance of low-frequency photoinduced capacitance was established ( Choi et al., 2020 ), while the origin of the negative capacitance through the formation of an inversion layer at interface leading to bending of energy band under illumination or open-circuit condition is also reported ( Feng et al., 2018 ). The surface polarization model, which describes the anomalous J-V hysteresis was also employed to expound the negative capacitance in PSCs.…”

Section: Introductionmentioning

confidence: 99%

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Mechanistic origin and unlocking of negative capacitance in perovskites solar cells

et al. 2021

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“…A related issue that has been intensely discussed in the area of PSC is the meaning of the often observed negative capacitance ,,,,− that causes great uncertainty of interpretation. We remark that the EC of Figure consists of a positive inductor not a negative capacitor.…”

Section: Background Of Impedance Spectroscopy and Hysteresismentioning

confidence: 99%

Theory of Hysteresis in Halide Perovskites by Integration of the Equivalent Circuit

2021

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Perovskite solar cells show a number of internal electronic−ionic effects that produce hysteresis in the current−voltage curves and a dependence of the temporal response on the conditions of the previous stimulus applied to the sample. There are many models and explanations in the literature, but predictive methods that may lead to an assessment of the solar cell behavior based on independent measurements are needed. Here, we develop a method to predict time domain response starting from the frequency domain response measured by impedance spectroscopy over a collection of steady states. The rationale of the method is to convert the impedance response into a set of differential equations, in which the internal state variables emerge naturally and need not be predefined in terms of a physical (drift/diffusion/interfaces) model. Then, one solves (integrates) the evolution for a required external perturbation such as voltage sweep at a constant rate (cyclic voltammetry). Using this method, we solve two elementary but relevant equivalent circuit models for perovskite solar cells and memristors, and we show the emergence of hysteresis in terms of the relevant time and energy constants that can be fully obtained from impedance spectroscopy. We demonstrate quantitatively a central insight in agreement with many observations: regular hysteresis is capacitive, and inverted hysteresis is inductive. Analysis of several types of perovskite solar cells shows excellent correlation of the type of equivalent circuit and the observed hysteresis. A new phenomenon of transformation from capacitive to inductive hysteresis in the course of the current−voltage curve is reported.

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The Origin of Photoinduced Capacitance in Perovskite Solar Cells: Beyond Ionic‐to‐Electronic Current Amplification

Cited by 11 publications

References 47 publications

Impedance Spectroscopy of Metal Halide Perovskite Solar Cells from the Perspective of Equivalent Circuits

Impedance Spectroscopy of Metal Halide Perovskite Solar Cells from the Perspective of Equivalent Circuits

Mechanistic origin and unlocking of negative capacitance in perovskites solar cells

Theory of Hysteresis in Halide Perovskites by Integration of the Equivalent Circuit

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