Degradation mechanism of planar-perovskite solar cells: correlating evolution of iodine distribution and photocurrent hysteresis

Ginting, Riski Titian; Jeon, Mi-Kyoung; Lee, Kwang-Jae; Jin, Won‐Yong; Kim, Tae-Wook; Kang, Jae‐Wook

doi:10.1039/c6ta09202k

Cited by 71 publications

(49 citation statements)

References 43 publications

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“…Our choice of a high doping density for the Spiro layer is motivated by Kelvin Probe Force Microscopy (KPFM) studies which indicate that very little of the built-in and applied voltage drops within the Spiro layer [82,83], suggestive of small depletion widths. However, as mentioned previously, this could alternatively be a result of ion uptake from the perovskite layer instead of intentional doping, a process that has been clearly observed for several intrinsic and extrinsic species [15,66,[84][85][86]. Setting larger doping in the titania layer causes the extent of region II to reach downward to lower voltages, eventually entering the negative bias range.…”

Section: The High-frequency Capacitance: C-v Measurementsmentioning

confidence: 83%

The two faces of capacitance: New interpretations for electrical impedance measurements of perovskite solar cells and their relation to hysteresis

Jacobs

Shen

Pfeffer

et al. 2018

Journal of Applied Physics

128

137

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Perovskite solar cells are notorious for exhibiting transient behaviour not seen in conventional inorganic semiconductor devices. Significant inroads have been made into understanding this fact in terms of rapid ion migration, now a well-established property of the prototype photovoltaic perovskite MAPbI3 and strongly implicated in the newer mixed compositions. Here we study the manifestations of ion migration in frequency-domain small-signal measurements, focusing on the popular technique of Electrical Impedance Spectroscopy (EIS). We provide new interpretations for a variety of previously puzzling features, including giant photo-induced low-frequency capacitance and negative capacitance in a variety of forms. We show that these apparently strange measurements can be rationalized by the splitting of AC current into two components, one associated with charge-storage, and the other with the quasi-steady-state recombination current of electrons and holes. The latter contribution to the capacitance can take either a positive or a negative sign, and is potentially very large when slow, voltage-sensitive processes such as ion migration are at play. Using numerical drift-diffusion semiconductor models, we show that giant photo-induced capacitance, inductive loop features, and low-frequency negative capacitance all emerge naturally as consequences of ion migration via its coupling to quasi-steady-state electron and hole currents. In doing so, we unify the understanding of EIS measurements with the comparably well-developed theory of rate dependent current-voltage (I-V) measurements in perovskite cells. Comparing the two techniques, we argue that EIS is more suitable for quantifying I-V hysteresis than conventional methods based on I-V sweeps, and demonstrate this application on a variety of cell types.

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Section: The High-frequency Capacitance: C-v Measurementsmentioning

confidence: 83%

The two faces of capacitance: New interpretations for electrical impedance measurements of perovskite solar cells and their relation to hysteresis

Jacobs

Shen

Pfeffer

et al. 2018

Journal of Applied Physics

128

137

View full text Add to dashboard Cite

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“…However, in general, as the employed measurement procedures are rather different and, in some cases, insufficiently controlled or specified, it is quite difficult to assess and compare the potential hysteretic effects: to what extent the hysteretic effects or their absence are truly related to fabrication methods or are a consequence of the measurement conditions? Since the dynamic hysteresis may be further linked to solar cell degradation [17][18][19][20], a detailed knowledge of the solar cell operation and the underlying mechanisms is crucial in the development of commercially ready PCSs. In this context, standardized measurement protocols (MPs) should be established in order to reliably extract the photovoltaic performance indicators as well as to select the most promising candidates with potential for enhanced stability.…”

Section: Introductionmentioning

confidence: 99%

How measurement protocols influence the dynamic J-V characteristics of perovskite solar cells: Theory and experiment

et al. 2018

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The dynamic effects observed in the J-V measurements represent one important hallmark in the behavior of the perovskite solar cells. Proper measurement protocols (MPs) should be employed for the experimental data reproducibility, in particular for a reliable evaluation of the power conversion efficiency (PCE), as well as for a meaningful characterization of the type and magnitude of the hysteresis. We discuss here several MPs by comparing the experimental J-V characteristics with simulated ones using the dynamic electrical model (DEM). Pre-poling conditions and bias scan rate can have a dramatic influence not only on the apparent solar cell performance, but also on the hysteretic phenomena. Under certain measurement conditions, a hysteresis-free behavior with relatively high PCEs may be observed, although the J-V characteristics may be far away from the stationary case. Furthermore, forward-reverse and reverse-forward bias scans show qualitatively different behaviors regarding the type of the hysteresis, normal and inverted, depending on the bias pre-poling. We emphasize here that correlated double-scans, forward-reverse or reverseforward, where the second scan is conducted in the opposite sweep direction and begins immediately after the first scan is complete, are essential for a correct assessment of the dynamic hysteresis. In this context, we define a hysteresis index which consistently assigns the hysteresis type and magnitude. Our DEM simulations, supported by experimental data, provide further guidance for an efficient and accurate determination of the stationary J-V characteristics, showing that the type and magnitude of the dynamic hysteresis may be affected by unintentional pre-conditioning in typical experiments.

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“…Our studies have focused exclusively on the temporal response of the photosynthetic apparatus to high-light exposure, but the snapshot TA technique is potentially valuable for tracking the excited state population and dynamics within any sample that changes over time. Some examples of this include tracking processes such as in situ thin-film formation for photovoltaic applications (Hernandez et al 2015;Wilson and Wong 2018) and degradation of perovskites by moisture/ O 2 (Wang et al 2015;Ginting et al 2017).…”

Section: Discussionmentioning

confidence: 99%

Snapshot transient absorption spectroscopy: toward in vivo investigations of nonphotochemical quenching mechanisms

et al. 2019

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Although the importance of nonphotochemical quenching (NPQ) on photosynthetic biomass production and crop yields is well established, the in vivo operation of the individual mechanisms contributing to overall NPQ is still a matter of controversy. In order to investigate the timescale and activation dynamics of specific quenching mechanisms, we have developed a technique called snapshot transient absorption (TA) spectroscopy, which can monitor molecular species involved in the quenching response with a time resolution of 30 s. Using intact thylakoid membrane samples, we show how conventional TA kinetic and spectral analyses enable the determination of the appropriate wavelength and time delay for snapshot TA experiments. As an example, we show how the chlorophyll-carotenoid charge transfer and excitation energy transfer mechanisms can be monitored based on signals corresponding to the carotenoid (Car) radical cation and Car S 1 excited state absorption, respectively. The use of snapshot TA spectroscopy together with the previously reported fluorescence lifetime snapshot technique (Sylak-Glassman et al. in Photosynth Res 127:69-76, 2016) provides valuable information such as the concurrent appearance of specific quenching species and overall quenching of excited Chl. Furthermore, we show that the snapshot TA technique can be successfully applied to completely intact photosynthetic organisms such as live cells of Nannochloropsis. This demonstrates that the snapshot TA technique is a valuable method for tracking the dynamics of intact samples that evolve over time, such as the photosynthetic system in response to highlight exposure.

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Degradation mechanism of planar-perovskite solar cells: correlating evolution of iodine distribution and photocurrent hysteresis

Cited by 71 publications

References 43 publications

The two faces of capacitance: New interpretations for electrical impedance measurements of perovskite solar cells and their relation to hysteresis

The two faces of capacitance: New interpretations for electrical impedance measurements of perovskite solar cells and their relation to hysteresis

How measurement protocols influence the dynamic J-V characteristics of perovskite solar cells: Theory and experiment

Snapshot transient absorption spectroscopy: toward in vivo investigations of nonphotochemical quenching mechanisms

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