Why perovskite solar cells with high efficiency show small IV-curve hysteresis

Neukom, Martin; Züfle, Simon; Knapp, Evelyne; Makha, Mohamed; Hany, Roland; Ruhstaller, Beat

doi:10.1016/j.solmat.2017.05.021

Cited by 60 publications

(58 citation statements)

References 41 publications

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“…This recombination scheme is also consistent with the large degree of J-V hysteresis seen in this device (see supporting information, Figure S13a) since we, and others, have previously shown that a combination of mobile ionic charge and interfacial recombination are necessary to observe hysteresis. 4,7,8,12,25 While computational studies on defective CH3NH3PbI3 crystals have not shown deep trapping states with easily accessible activation energies, 26,27 the interface between CH3NH3PbI3 and the compact TiO2 layer is likely to contain a high density of deep inter-bandgap electronic states as commonly observed at the TiO2 hole transporting material interface in dye sensitised solar cells. 28,29 Furthermore, recent studies have shown that recombination rates at the hole transport layer interface are significantly influenced by doping 30 and that the CH3NH3PbI3 interface with heavily lithium-doped Spiro-OMeTAD is a site of significant recombination.…”

Section: Recombination Mechanism In the Mesoporous Al2o3 Cellmentioning

confidence: 99%

“…There is now considerable evidence to indicate that J-V hysteresis in hybrid perovskite devices results from a combination of the effects of redistribution of mobile ionic defects and high rates of recombination at the perovskite-transport layer interfaces. 4,[8][9][10][11][12] Consequently, it is tempting to speculate that the dominant recombination mechanism in a device evolves with the VOC evolution, or that the recombination mechanism at steady-state could be a function of light intensity. The results presented herein show that such changes are not required to explain much of the behaviour observed when examining the ideality factor of perovskite solar cells.…”

Section: Introductionmentioning

confidence: 99%

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Identifying Dominant Recombination Mechanisms in Perovskite Solar Cells by Measuring the Transient Ideality Factor

et al. 2019

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The ideality factor determined by measuring the open circuit voltage (VOC) as function of light intensity is often used as a means to identify the dominant recombination mechanism in solar cells. However, applying this 'Suns-VOC' technique to perovskite cells is problematic since the VOC evolves with time in a way which depends on the previously applied bias (Vpre), the light intensity, and the device architecture/processing. Here we show that the dominant recombination mechanism in two structurally similar CH3NH3PbI3 devices containing either mesoporous Al2O3 or TiO2 layers can be identified from the signature of the transient ideality factor following application of a forward bias, Vpre, to the device in the dark. The transient ideality factor, is measured by monitoring the evolution of VOC as a function of time at different light intensities. The initial values of ideality found using this technique were consistent with corresponding photoluminescence vs intensity as well as electroluminescence vs current density measurements. Time-dependent simulations of the measurement on modelled devices, which include the effects of mobile ionic charge, show that Shockley Read Hall (SRH) recombination through deep traps at the charge collection interfaces is dominant in both devices. Using superimposed transient photovoltage measurements of the evolving VOC on bifacial devices we further show that the charge collection interface extends throughout the mesoporous TiO2 layer, consistent with a transient ideality signature corresponding to SRH recombination in the bulk of the film. This information could not be inferred from an ideality factor determined from the steady-state VOC values alone. We anticipate that the method we have developed will be useful for identifying performance bottlenecks in new variants of perovskite solar cells by comparison with the transient ideality signatures we have predicted for a range of possible recombination schemes.

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Section: Recombination Mechanism In the Mesoporous Al2o3 Cellmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Identifying Dominant Recombination Mechanisms in Perovskite Solar Cells by Measuring the Transient Ideality Factor

et al. 2019

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“…Debye layer about x = 0. Considering first the Debye layer about x = 0, we use the rescaling (21) to rewrite the governing equations (16)- (17) in terms of the rescaled spatial variable ζ, yielding the boundary layer equations:…”

Section: A Solution For P and φ In The Debye Layersmentioning

confidence: 99%

“…In contrast, drift-diffusion models, which are applicable on the nanometre length scale and upward, describe the motion of electrons, holes and ion vacancies. Such models have been presented and solved in a number of works [28,30,23,34,6,10,14,40,21]. However it is notable that, with the exception of two [23,28], all of these works use parameter values that are very far from realistic.…”

Section: Introductionmentioning

confidence: 99%

Systematic derivation of a surface polarisation model for planar perovskite solar cells

Courtier¹,

Foster

O’Kane³

et al. 2018

Eur. J. Appl. Math

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Increasing evidence suggests that the presence of mobile ions in perovskite solar cells (PSCs) can cause a current-voltage curve hysteresis. Steady state and transient current-voltage characteristics of a planar metal halide CH3NH3PbI3 PSC are analysed with a drift-diffusion model that accounts for both charge transport and ion vacancy motion. The high ion vacancy density within the perovskite layer gives rise to narrow Debye layers (typical width ∼2 nm), adjacent to the interfaces with the transport layers, over which large drops in the electric potential occur and in which significant charge is stored. Large disparities between (I) the width of the Debye layers and that of the perovskite layer (∼600 nm) and (II) the ion vacancy density and the charge carrier densities motivate an asymptotic approach to solving the model, while the stiffness of the equations renders standard solution methods unreliable. We derive a simplified surface polarisation model in which the slow ion dynamics are replaced by interfacial (non-linear) capacitances at the perovskite interfaces. Favourable comparison is made between the results of the asymptotic approach and numerical solutions for a realistic cell over a wide range of operating conditions of practical interest.

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“…It was established by various modeling and experimentation that hysteresis is weak when surface recombination is low and diffusion length is long. 182 Improved crystallinity, better fabrication process, and improved contacts are going to continue to improve hysteresis. HTMs influence hysteresis and J-V curve.…”

Section: Hysteresismentioning

confidence: 99%

Factors affecting the stability of perovskite solar cells: a comprehensive review

2019

J. Photon. Energy

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Accelerated depletion of fossil fuel, energy demands, and pollution force us to choose renewable and eco-friendly energy resources. Solar cells are considered as an efficient replacement for fossil fuel. In the family of solar cells, silicon-based solar cells and perovskite solar cells (PSC) have displayed significant power conversion efficiency (PCE). Perovskites have been investigated extensively over the past two decades, due to their advantageous properties, such as high absorption coefficient, efficient carrier mobility, long charge diffusion length, and direct bandgap. These features make PSC a prospective candidate to replace silicon in solar cells. By 2018, PSC achieved an encouraging PCE of 23.3%. However, low stability and toxicity have retarded the commercialization of PSC. With the aim of assisting junior researchers, we consider the latest achievements in this domain and review the field from a stability and performance perspective. We emphasize recent developments and methodologies to overcome drawbacks concerning stability and toxicity.

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Why perovskite solar cells with high efficiency show small IV-curve hysteresis

Cited by 60 publications

References 41 publications

Identifying Dominant Recombination Mechanisms in Perovskite Solar Cells by Measuring the Transient Ideality Factor

Identifying Dominant Recombination Mechanisms in Perovskite Solar Cells by Measuring the Transient Ideality Factor

Systematic derivation of a surface polarisation model for planar perovskite solar cells

Factors affecting the stability of perovskite solar cells: a comprehensive review

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