Influence of bromide content on iodide migration in inverted MAPb(I1−xBrx)3perovskite solar cells

García-Rodríguez, Rodrigo; Ferdani, Dominic; Pering, Samuel; Baker, Peter J.; Cameron, Petra J.

doi:10.1039/c9ta08848b

Cited by 50 publications

(66 citation statements)

References 76 publications

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“…Figure 11 illustrates the Nyquist plots for devices fabricated using NiO x and 5% Zn-NiO x thin films annealed at 250 • C. EIS measurement was taken at one solar illumination using a frequency range from 10 Hz to 1 MHz with an AC amplitude of 0.01 V, and providing a bias voltage that matched the open-circuit voltage. The impedance curve was observed at three frequency regions where the high-frequency (HF) regime correlates with charge transport resistance (Rct) at the HTL/perovskite interface, mid-frequency (MF) region is related to charge recombination, and low-frequency (LF) has been associated to iodide ion modulated recombination/injection process [47]. The curves were fitted with the equivalent circuit and the calculated Rct values are~60.38 Ω and 45.62 Ω for NiO x and 5% Zn-NiO x devices, respectively.…”

Section: Resultsmentioning

confidence: 99%

Combustion Processed Nickel Oxide and Zinc Doped Nickel Oxide Thin Films as a Hole Transport Layer for Perovskite Solar Cells

2021

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Combustion processed nickel oxide (NiOx) thin film is considered as an alternative to the sol-gel processed hole transport layer for perovskite solar cells (PSCs). In this paper, NiOx thin film was prepared by the solution–combustion process at 250 °C, a temperature lower than the actual reaction temperature. Furthermore, the properties of the NiOx hole transport layer (HTL) in PSCs were enhanced by the incorporation of zinc (Zn) in NiOx thin films. X-ray diffraction and X-ray photoelectron spectroscopy results revealed that the formation of NiOx was achieved at lower annealing temperature, which confirms the process of the combustion reaction. The electrical conductivity was greatly improved with Zn doping into the NiOx crystal lattice. Better photoluminescence (PL) quenching, and low PL lifetime decay were responsible for better charge separation in 5% Zn doped NiOx, which results in improved device performance of PSCs. The maximum power conversion efficiency of inverted PSCs made with pristine NiOx and 5% Zn-NiOx as the HTL was 13.62% and 14.87%, respectively. Both the devices exhibited better stability than the PEDOT:PSS (control) device in an ambient condition.

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Section: Resultsmentioning

confidence: 99%

Combustion Processed Nickel Oxide and Zinc Doped Nickel Oxide Thin Films as a Hole Transport Layer for Perovskite Solar Cells

2021

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“…So far there have only been a limited number of studies focusing on these regimes, using AC impedance spectroscopy or DC polarization measurements. 15 , 16 Although these works shed light on ion migration in mixed-halide perovskites, the full picture remains elusive, specifically whether the trends observed stem from iodide or bromide migration, and how to attribute the relative contributions to the ion migration process, in terms of migration activation energy, ion diffusion coefficient, and concentration of mobile ions.…”

Section: Introductionmentioning

confidence: 99%

Reduced Barrier for Ion Migration in Mixed-Halide Perovskites

McGovern

Grimaldi

Futscher

et al. 2021

ACS Appl. Energy Mater.

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Halide alloying in metal halide perovskites is a useful tool for optoelectronic applications requiring a specific bandgap. However, mixed-halide perovskites show ion migration in the perovskite layer, leading to phase segregation and reducing the long-term stability of the devices. Here, we study the ion migration process in methylammonium-based mixed-halide perovskites with varying ratios of bromide to iodide. We find that the mixed-halide perovskites show two separate halide migration processes, in contrast to pure-phase perovskites, which show only a unique halide migration component. Compared to pure-halide perovskites, these processes have lower activation energies, facilitating ion migration in mixed versus pure-phase perovskites, and have a higher density of mobile ions. Under illumination, we find that the concentration of mobile halide ions is further increased and notice the emergence of a migration process involving methylammonium cations. Quantifying the ion migration processes in mixed-halide perovskites shines light on the key parameters allowing the design of bandgap-tunable perovskite solar cells with long-term stability.

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“…Critically, the study highlights that the LPK blocks the escape of MAI, making the degradation process reversible, further affirming that LPKs suppress both vacancy migration, as well as, interfacial ion migration. [119][120][121] In devices, the introduction of an LPK layer between the 3D material and the hole transporting material (HTM) has been shown to improve device stability and reduce hysteresis. [115,[123][124][125] For instance, Grancini et al showed that the aminovaleric acid (AVA) based perovskite (AVA) 2 PbI 4 /CH 3 NH 3 PbI 3 ) is stable for one year.…”

Section: Enhancing Stability With Layered Structuresmentioning

confidence: 99%

Layered Perovskites in Solar Cells: Structure, Optoelectronic Properties, and Device Design

Sirbu

Balogun

Milot

et al. 2021

Advanced Energy Materials

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optoelectronic properties akin to industrial juggernauts gallium arsenide and silicon. [1,2] Yet, the materials are compatible with solution-processing techniques such as inkjet printing and spray coating. [3] This unprecedented combination has led to the development of solar cells which already show power conversion efficiencies of over 25%, similar to state-of-the-art poly-Si and other thin-film technologies, in just over 10 years of development. [4] Hybrid perovskites are particularly interesting for indoor applications, with impressive efficiencies of over 35% demonstrated under indoor illumination which may prove a viable option to power the ever expanding Internet of Things. [5] Rather than competing with the current technology giants, perovskites can work together with other solar cell technologies in a tandem configuration. Record efficiencies of over 29% for silicon-perovskite tandem solar cells have already been reported and further progress is expected in the near future. [6] Although perovskite solar cells (PSCs) are on the verge of mass production, two main challenges remain: stability [7] and toxicity. [8] Multiple reviews already address the toxicity concern, and it will not be discussed here. [9][10][11] Layered hybrid perovskites (LPKs) have emerged as an answer to battle stability concerns. Although known for decades, LPKs have only recently been incorporated in photovoltaic (PV) applications, resulting in modest device power conversion efficiencies due to poorer optoelectronic properties. [12][13][14] However, their key advantage is the stabilizing effects of the organic interlayers, which prevents perovskite degradation. [15,16] The organic spacer inhibits ion migration which prevents the formation of irreversible degradation products. [17] Alternatively, LPKs can be deposited over the state-of-the-art perovskite materials to combine the high performance of 3D perovskites with the stabilizing properties of LPKs. [15] Here, the limiting factor is inefficient charge transport across the organic interlayer, currently preventing the full exploitation of the layered structure in PSCs.This can be approached in two ways, either by keeping the LPK layer very thin, currently the most popular approach, or by increasing the electrical conductivity of the material. [18,19] The conductivity can be enhanced through increasing the number of inorganic layers n, but this comes at the price of reduced stability. [20][21][22] The better approach is to enhance the charge transport in LPKs through the molecular engineering of the organic Layered hybrid perovskites (LPKs) have emerged as a viable solution to address perovskite stability concerns and enable their implementation in wide-scale energy harvesting. Yet, although more stable, the performance of devices incorporating LPKs still lags behind that of state-of-the-art, multication perovskite materials. This is typically assigned to their poor charge transport, currently caused by the choice of cations used within the organic layer. On balance, a compromise bet...

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Influence of bromide content on iodide migration in inverted MAPb(I_1−xBr_x)₃perovskite solar cells

Abstract: Impedance spectroscopy shows the bromide concentration required to supress the low frequency response from mobile ions.

Cited by 50 publications

References 76 publications

Combustion Processed Nickel Oxide and Zinc Doped Nickel Oxide Thin Films as a Hole Transport Layer for Perovskite Solar Cells

Combustion Processed Nickel Oxide and Zinc Doped Nickel Oxide Thin Films as a Hole Transport Layer for Perovskite Solar Cells

Reduced Barrier for Ion Migration in Mixed-Halide Perovskites

Layered Perovskites in Solar Cells: Structure, Optoelectronic Properties, and Device Design

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