Light capacitances in silicon and perovskite solar cells

Almora, Osbel; García-Belmonte, Germà

doi:10.1016/j.solener.2019.07.048

“…The high frequency region from IS reproduces earlier described features. 35,36 On the other hand, at low frequencies ( <1kHz) LIMIS seems to reproduce very well the IS spectra, in both the impedance Nyquist plot (2 arcs in Figure 5b) and the capacitance Bode plot (2 steps in Figure 5c). Figure S2) and (b) representative impedance Nyquist plot (see Figure S3).…”

Section: Experimental Limis and Is Spectramentioning

confidence: 77%

“…The capacitance bode plots are shown in Figure S3 with the respective simulations to Figure 8b showing an exponential increase possibly due to diffusion capacitance. 35,40 In this case the from LIMIs is nearly half of that from IS, so from (17):…”

Section: Numeric Approach: the Equivalent Circuitsmentioning

confidence: 99%

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

Almora

¹

,

Zhao

²

,

Du

³

et al. 2020

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Potentiostatic impedance spectroscopy (IS) is a well stablished characterization technique for elucidating the electric resistivity and capacitive features of materials and devices. In the case of solar cells, by applying a small voltage perturbation the current signal is recorded and the recombination processes and defect distributions are among the typical outcomes in IS studies. In this work a photo-impedance approach, named "light intensity modulated impedance spectroscopy" (LIMIS), is first tested in all-solid-state photovoltaic cells by recording the individual photocurrent (IMPS) and photovoltage (IMVS) responsivity signals due to a small light perturbation at opencircuit (OC), and combining them: LIMIS=IMVS/IMPS. The experimental LIMIS spectra from silicon, organic, and perovskite solar cells are presented and compared with IS. An analysis of the equivalent circuit numerical models for total resistive and capacitive features is discussed. Our theoretical findings show a correction to the lifetimes evaluations by obtaining the total differential resistances and capacitances combining IS and LIMIS measurements. This correction addresses the discrepancies among different techniques, as shown with transient photovoltage. The experimental differences between IS and LIMIS (i) proves the unviability of the superposition principle, (ii) suggest a bias-dependent photo-current correction to the empirical Shockley equation of the steady-state current at different illumination intensities around OC and (iii) are proposed as a potential figure of merit for characterizing performance and stability of solar cells. In addition, new features are reported for the low-frequency capacitance of perovskite solar cells, measured by IS and LIMIS.

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“…The high frequency region from IS reproduces earlier described features. 32,33 On the other hand, at low frequencies ( <1kHz) LIMIS seems to reproduce very well the IS spectra, in both the impedance Nyquist plot (2 arcs in Figure 5b) and the capacitance Bode plot (2 steps in Figure 5c). Moreover, one final interesting correlation is remarked regarding the comparison between LIMIS and IS in terms of Δ Ψ .…”

Section: Experimental Limis and Is Spectramentioning

confidence: 77%

“…The capacitance bode plots are shown in Figure S3 with the respective simulations to in Figure 8b showing an exponential increase possibly due to diffusion capacitance. 32,37 In this case the from LIMIs is nearly half of that from IS, so from (17):…”

Section: Numeric Approach: the Equivalent Circuitsmentioning

confidence: 99%

Analytical model for light modulating impedance spectroscopy (LIMIS) in all-solid-state p-n junction solar cells at open-circuit

Almora

¹

,

Miravet

²

,

Matt

³

et al. 2020

Applied Physics Letters

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Potentiostatic impedance spectroscopy (IS) is a well stablished characterization technique for elucidating the electric resistivity and capacitive features of materials and devices. In the case of solar cells, by applying a small voltage perturbation the current signal is recorded and the recombination processes and defect distributions are among the typical outcomes in IS studies. In this work a photo-impedance approach, named "light intensity modulated impedance spectroscopy" (LIMIS), is first tested in all-solid-state photovoltaic cells by recording the individual photocurrent (IMPS) and photovoltage (IMVS) responsivity signals due to a small light perturbation at opencircuit (OC), and combining them: LIMIS=IMVS/IMPS. The experimental LIMIS spectra from silicon, organic, and perovskite solar cells are presented and compared with IS. An analysis of the equivalent circuit numerical models for total resistive and capacitive features is discussed. Our theoretical findings show a correction to the lifetimes evaluations by obtaining the total differential resistances and capacitances combining IS and LIMIS measurements. This correction addresses the discrepancies among different techniques, as shown with transient photovoltage. The experimental differences between IS and LIMIS (i) proves the unviability of the superposition principle, (ii) suggest a bias-dependent photo-current correction to the empirical Shockley equation of the steady-state current at different illumination intensities around OC and (iii) are proposed as a potential figure of merit for characterizing performance and stability of solar cells. In addition, new features are reported for the low-frequency capacitance of perovskite solar cells, measured by IS and LIMIS.

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“…From a morphological point of view, water begins to collapse the grain boundaries of perovskite film, broken their interconnectivity and fabricating isolating trails that increase the recombination pathways. [19] The consequences are optical absorption losses and major recombination processes that leads to a detriment of the photovoltaic performance of the cell. MA + can rapidly diffuse and separate from the PbI 6 octahedral, leading to the appearance of the non-photoactive phase with a yellow-white colour, degrading completely the material by turning it back to PbI 2 and MA + compounds irreversibly ( Figure 1).…”

Section: Introductionmentioning

confidence: 99%

Crystalline Clear or Not: Beneficial and Harmful Effects of Water in Perovskite Solar Cells

Aranda

¹

,

Guerrero

²

,

Bisquert

³

2019

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Clarification of how water affects the photovoltaic performance of perovskite solar cells is one of the major challenges to successfully develop a large-scale low-cost fabrication process. Many authors have reported beneficial effects of moisture during the fabrication of perovskite solar cells (PSCs), such as enhanced crystallinity, photoluminescence and photovoltage. However, the highest power conversion efficiency reported until this date was obtained under completely dry atmosphere conditions, avoiding the presence of water during perovskite formulation and preserving the damage caused by moisture exposure with encapsulation techniques. This apparent contradiction makes patent the necessity of an extensive clarification to establish the conditions in which water represents a beneficial or harmful factor in the development of high efficiency and stable perovskite devices. In this review, we summarized the effects of water, both as an additive into the perovskite formulation as an additive and as moisture exposure during fabrication. We discuss in depth the structural and chemical effects, analysing also the photovoltaic consequences during operation conditions. As a final input, we remark a useful method to perform high efficiency PSCs under different lab ambient conditions and highlight the latest advances in hydrophobic devices and encapsulation techniques.

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Light capacitances in silicon and perovskite solar cells

Cited by 24 publications

References 61 publications

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

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

Analytical model for light modulating impedance spectroscopy (LIMIS) in all-solid-state p-n junction solar cells at open-circuit

Crystalline Clear or Not: Beneficial and Harmful Effects of Water in Perovskite Solar Cells

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