Investigating charge dynamics in halide perovskite-sensitized mesostructured solar cells

Roiati, Vittoria; Colella, Silvia; Lerario, Giovanni; Marco, Luisa De; Rizzo, Aurora; Listorti, Andrea; Gigli, Giuseppe

doi:10.1039/c3ee43991g

Cited by 155 publications

(161 citation statements)

References 40 publications

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“…To the best of our knowledge, TPV data have not been published on CH 3 NH 3 PbI 3− X Cl X PSCs employing a mesoporous alumina scaffold, however several studies have considered photovoltage decay behavior in CH 3 NH 3 PbI 3 PSCs employing a mesoporous TiO 2 scaffold. [ 39,56,57 ] Critically, TPV decays in these device architectures were strongly biexponential, in contrast to the monoexponential behavior apparently observed here. O'Regan et al proposed that under 1 sun conditions, photovoltage decays with a lifetime of around 1 μs correspond to the dominant electron/hole recombination channel.…”

Section: Resultscontrasting

confidence: 47%

“…O'Regan et al proposed that under 1 sun conditions, photovoltage decays with a lifetime of around 1 μs correspond to the dominant electron/hole recombination channel. [ 39 ] The physical location of this recombination process was not confi rmed, however related work suggested that the long-lifetime decay component relates to charge recombination within the TiO 2 scaffold [ 56,57 ] with the shorter component (up to several microseconds) quantifying carrier lifetime within the perovskite layer. Although we caution against the comparison of absolute TPV decay times between independent studies, due to likely variations in device preparation and measurement conditions, in our solar cells the volume fraction of TiO 2 is relatively low because the metal oxide exists as a compact cathode interface layer only.…”

Section: Resultsmentioning

confidence: 99%

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Oxygen Degradation in Mesoporous Al₂O₃/CH₃NH₃PbI_3‐_xCl_x Perovskite Solar Cells: Kinetics and Mechanisms

Pearson

Eperon

Hopkinson

et al. 2016

Advanced Energy Materials

232

120

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unexpectedly clean electronic properties of these semiconductors have led to the demonstration of proof-of-concept PV devices with an initial effi ciency that outperforms competing 'next-generation' technologies such as dye-sensitized, organic, and quantum dot solar cells, and even matches that of commercially deployed PV. [ 6 ] Other attractive characteristics of hybrid perovskites include the low embedded costs of materials processing and the ability to tune the properties of the semiconductor through changes in chemical composition. [ 1,[7][8][9][10] All of these factors have led to hybrid perovskites being considered as disruptive materials in a wide range of technology applications; [11][12][13][14][15][16] interest from the materials science research community is both substantial and rapidly maturing. Realizing the technology potential of hybrid perovskites necessitates a thorough understanding of the degradation mechanisms that limit the lifetime of devices, and identifying solutions to mitigate these. This exercise is nontrivial because of the various factors that can affect device performance: light, heat, moisture, oxygen, mechanical and electrical stresses, and combinations thereof. [ 17,18 ] Currently, perovskite solar cells (PSCs) based on the "triple layer" architecture with a thick carbon back electrode have demonstrated perhaps the most stable performance characteristics of all PSCs. [ 19 ] These devices, based on the mixed cation perovskite (5-AVA) X (MA) 1− X PbI 3 (where 5-AVA corresponds to 5-ammoniumvaleric acid), have been shown to maintain their initial power conversion effi ciency (PCE) of approximately 10% over 1000 h continuous simulated solar illumination, [ 20 ] dark storage for three months at elevated temperatures and humidity (85 °C/85%) and a minimum of 7 d operation in real-world conditions (Jeddah, Saudi Arabia). [ 21 ] Although clearly commendable, it is apparent that signifi cant work is required to realize PSCs with high stability and high performance, where promising stability metrics are combined with the certifi ed PCE values for champion devices. [ 22 ] To elucidate the underlying mechanisms for degradation in hybrid perovskites and guide the development of intrinsically stable devices, considerable work has been undertaken on the archetypal semiconductor of the research fi eld: CH 3 NH 3 PbI 3 . It is known that this material (and other single or mixed-halide derivatives) are particularly sensitive to moisture, [ 1,7,17,[23][24][25][26] where the proposed chemical reactions involving water result in decomposition of the perovskite into its precursor components via The rapid pace of development for hybrid perovskite photovoltaics has recently resulted in promising fi gures of merit being obtained with regard to device stability. Rather than relying upon expensive barrier materials, realizing market-competitive lifetimes is likely to require the development of intrinsically stable devices, and to this end accelerated aging tests can help identify degradation mechanisms tha...

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Section: Resultscontrasting

confidence: 47%

Section: Resultsmentioning

confidence: 99%

Oxygen Degradation in Mesoporous Al₂O₃/CH₃NH₃PbI_3‐_xCl_x Perovskite Solar Cells: Kinetics and Mechanisms

Pearson

Eperon

Hopkinson

et al. 2016

Advanced Energy Materials

232

120

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“…7). The PL quenching measurements are related to the electron-hole diffusion lengths and lifetimes 37,38 . As shown in Supplementary Fig.…”

Section: Resultsmentioning

confidence: 99%

Efficient hole-blocking layer-free planar halide perovskite thin-film solar cells

et al. 2015

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Efficient lead halide perovskite solar cells use hole-blocking layers to help collection of photogenerated electrons and to achieve high open-circuit voltages. Here, we report the realization of efficient perovskite solar cells grown directly on fluorine-doped tin oxide-coated substrates without using any hole-blocking layers. With ultraviolet-ozone treatment of the substrates, a planar Au/hole-transporting material/CH 3 NH 3 PbI 3-x Cl x /substrate cell processed by a solution method has achieved a power conversion efficiency of over 14% and an open-circuit voltage of 1.06 V measured under reverse voltage scan. The open-circuit voltage is as high as that of our best reference cell with a TiO 2 hole-blocking layer. Besides ultraviolet-ozone treatment, we find that involving Cl in the synthesis is another key for realizing high open-circuit voltage perovskite solar cells without hole-blocking layers. Our results suggest that TiO 2 may not be the ultimate interfacial material for achieving high-performance perovskite solar cells.

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“…There is also debate about how to correctly measure the recombination and transport times, the charge density, and even the correct measurement of efficiency. [5][6][7][8][9][10][11][12][13][14][15][16][17] The debate about characterization centers on the interpretation of various time constants that can be measured by optical and electrical means. These time constants range from <1 µs to >100 µs.…”

Section: Introductionmentioning

confidence: 99%

Optoelectronic Studies of Methylammonium Lead Iodide Perovskite Solar Cells with Mesoporous TiO₂: Separation of Electronic and Chemical Charge Storage, Understanding Two Recombination Lifetimes, and the Evolution of Band Offsets during J–V Hysteresis

et al. 2015

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We have examined methylammonium lead iodide (MAPI) cells of the design FTO/sTiO 2 / mpTiO 2 /MAPI/Spiro-OMeTAD/Au using fast opto-electronic techniques including transient photovoltage, differential capacitance, charge extraction, current interrupt, and chronophotoamperometry. The data allow several important conclusions regarding the physics and proper characterization of these cells. 1) In mpTiO 2 /MAPI cells there are two kinds of extractable charge stored under operation: a capacitive electronic charge (~0.2 µC/cm 2 ), and another, much larger, charge (40 µC/cm 2 ) which could be the result of dipole realignment, or the effect of mobile ions. The capacitive charge is ~10 times smaller than in mpTiO 2 /dye/SpiroOMeTAD cells with similar mpTiO 2 thickness. 2) Transient photovoltage decays are strongly double exponential with two time constants that differ by a factor of ~5, independent of bias light intensity. We show that the fast decay (~1 µs at one sun) can be assigned to the predominant charge recombination pathway in the cell. We examine and reject the possibilities that the fast decay is due to ferro-electric relaxation, or to the bulk photovoltaic effect. We provide two possible schematic electrical models for the cells that reproduce the V oc and TPV data.3) It has been previously observed that MAPI cells frequently show current/voltage hysteresis. For example, an increase in J sc and V oc is observed on the return sweep of a cyclic JV. Our capacitance vs V oc data indicate that the hysteresis involves a change in internal potential gradients, most likely a shift in band offsets at the TiO 2 /MAPI interface. The TPV results show that the V oc hysteresis is not due to a change in recombination rate constant. Calculation of recombination flux at V oc shows that the hysteresis is also not due to an increase in charge separation efficiency, and that charge generation is not a function of applied bias. We also show that the JV hysteresis is not a light driven effect, but is caused by exposure to forward bias, light or dark.

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Investigating charge dynamics in halide perovskite-sensitized mesostructured solar cells

Abstract: Evidence of complementary carrier percolation paths in halide perovskite-sensitized mesostructured solar cells.

Cited by 155 publications

References 40 publications

Oxygen Degradation in Mesoporous Al₂O₃/CH₃NH₃PbI_3‐_xCl_x Perovskite Solar Cells: Kinetics and Mechanisms

Oxygen Degradation in Mesoporous Al₂O₃/CH₃NH₃PbI_3‐_xCl_x Perovskite Solar Cells: Kinetics and Mechanisms

Efficient hole-blocking layer-free planar halide perovskite thin-film solar cells

Optoelectronic Studies of Methylammonium Lead Iodide Perovskite Solar Cells with Mesoporous TiO₂: Separation of Electronic and Chemical Charge Storage, Understanding Two Recombination Lifetimes, and the Evolution of Band Offsets during J–V Hysteresis

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Investigating charge dynamics in halide perovskite-sensitized mesostructured solar cells

Abstract: Evidence of complementary carrier percolation paths in halide perovskite-sensitized mesostructured solar cells.

Cited by 155 publications

References 40 publications

Oxygen Degradation in Mesoporous Al2O3/CH3NH3PbI3‐xClx Perovskite Solar Cells: Kinetics and Mechanisms

Oxygen Degradation in Mesoporous Al2O3/CH3NH3PbI3‐xClx Perovskite Solar Cells: Kinetics and Mechanisms

Efficient hole-blocking layer-free planar halide perovskite thin-film solar cells

Optoelectronic Studies of Methylammonium Lead Iodide Perovskite Solar Cells with Mesoporous TiO2: Separation of Electronic and Chemical Charge Storage, Understanding Two Recombination Lifetimes, and the Evolution of Band Offsets during J–V Hysteresis

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Oxygen Degradation in Mesoporous Al₂O₃/CH₃NH₃PbI_3‐_xCl_x Perovskite Solar Cells: Kinetics and Mechanisms

Oxygen Degradation in Mesoporous Al₂O₃/CH₃NH₃PbI_3‐_xCl_x Perovskite Solar Cells: Kinetics and Mechanisms

Optoelectronic Studies of Methylammonium Lead Iodide Perovskite Solar Cells with Mesoporous TiO₂: Separation of Electronic and Chemical Charge Storage, Understanding Two Recombination Lifetimes, and the Evolution of Band Offsets during J–V Hysteresis