Grain Size Influences Activation Energy and Migration Pathways in MAPbBr<sub>3</sub> Perovskite Solar Cells

McGovern, Lucie; Koschany, Isabel; Grimaldi, Gianluca; Muscarella, Loreta A.; Ehrler, Bruno

doi:10.1021/acs.jpclett.1c00205

Cited by 91 publications

(82 citation statements)

References 27 publications

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“…This is because the activation energy barrier is determined from an Arrhenius plot that depends on the change in time constant with temperature in each film (slope of ln(1/τ) against 1/k B T), instead of the absolute value of the time constant itself. Another way of looking at this is that the activation energy barrier is primarily affected by the local environment the ions are in, [48,49] and changes in the internal electric field by a factor of two would not influence the mechanism of ion migration. The changes in activation energy would therefore reflect the effects of a change in grain boundary density.…”

Section: Charge-carrier and Ion Transportmentioning

confidence: 99%

Understanding the Role of Grain Boundaries on Charge‐Carrier and Ion Transport in Cs₂AgBiBr₆ Thin Films

Senanayak

Dai

et al. 2021

Adv Funct Materials

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Halide double perovskites have gained significant attention, owing to their composition of low-toxicity elements, stability in air, and recent demonstrations of long charge-carrier lifetimes that can exceed 1 µs. In particular, Cs 2 AgBiBr 6 is the subject of many investigations in photovoltaic devices. However, the efficiencies of solar cells based on this double perovskite are still far from the theoretical efficiency limit of the material. Here, the role of grain size on the optoelectronic properties of Cs 2 AgBiBr 6 thin films is investigated. It is shown through cathodoluminescence measurements that grain boundaries are the dominant nonradiative recombination sites. It also demonstrates through field-effect transistor and temperature-dependent transient current measurements that grain boundaries act as the main channels for ion transport. Interestingly, a positive correlation between carrier mobility and temperature is found, which resembles the hopping mechanism often seen in organic semiconductors. These findings explain the discrepancy between the long diffusion lengths >1 µm found in Cs 2 AgBiBr 6 single crystals versus the limited performance achieved in their thin film counterparts. This work shows that mitigating the impact of grain boundaries will be critical for these double perovskite thin films to reach the performance achievable based on their intrinsic single-crystal properties.

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Section: Charge-carrier and Ion Transportmentioning

confidence: 99%

Understanding the Role of Grain Boundaries on Charge‐Carrier and Ion Transport in Cs₂AgBiBr₆ Thin Films

Senanayak

Dai

et al. 2021

Adv Funct Materials

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“…The TID method can detect both moving cations and anions, which is a unique advantage in investigating the ion migration process compared with TDC [21][22][23][24] and IS [25][26][27] measurements. The TID method is well established in PSCs by Futscher et al [28][29][30][31] and Reichert et al [32,33] The TID method was conducted on mixed-composition perovskite (PEABr 0.2 Cs 0.4 MA 0.6 PbBr 3 ) by Futscher et al [29] However, as PEABr 0.2 Cs 0.4 MA 0.6 PbBr 3 is typically used for light-emitting diodes (LEDs), the influence of ion migration on mixed-composition PSCs has not been further studied. [29] Because of the unique advantage of the TID method, it provides a great platform for investigating the influence of the migration of both cations and anions on mixed-composition PSCs.…”

mentioning

confidence: 99%

Understanding the Influence of Cation and Anion Migration on Mixed‐Composition Perovskite Solar Cells via Transient Ion Drift

Kan

Hang

et al. 2021

Physica Rapid Research Ltrs

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In just a decade, the power conversion efficiency (PCE) of perovskite solar cells (PSCs) has increased from 3.8 [1] to 25.5%. [2] However, the most critical challenge preventing PSCs from being the next generation of solar cells is their poor longterm stability. [3,4] Ion migration has been identified as one of the most important causes of this poor stability. [5][6][7] It has been hypothesized by some researchers that ion migration in light-harvesting layers screens the built-in potential, leading to the anomalous hysteresis phenomenon [8,9] and the accumulation of ions at the interface between perovskite and transporting layers, thus modifying the band diagram of the devices and leading to degradation of the PSCs. [9,10] Furthermore, if mobile ions (MA þ , I À ) out-diffuse to transporting layers, or even to metal electrodes, it will result in a deterioration of the cell performance either by generating deep-level trap states in transporting layers or by an enhanced chemical reaction with transporting materials or electrodes. [11][12][13] MAPbI 3 is a prototype perovskite material used to fabricate PSCs. However, it suffers from ion migration and poor stability. [14,15] To overcome these problems, researchers have used a composition modulation strategy to alleviate ion migration in PSCs, attempting to achieve PSC devices with better performance and better long-term stability. Typically, perovskite compositions with a combination of mixed cations (FA þ , MA þ ) and mixed anions (Br À , I À ) were used to produce PSC devices with reduced hysteresis and better stability. [16] In addition, a small amount of Cs þ ions were added to the perovskite layers to improve the reproducibility and stability of PSCs because Cs þ ions are suggested to stabilize the crystal structure of perovskite. [17,18] Hence, mixed-composition perovskites with mixed cations and anions have been extensively studied and applied in the scope of PSCs, resulting in state-of-the-art PSCs. [19,20] Different methods, such as temperature-dependent conductivity (TDC) measurements [21][22][23][24] and impedance spectroscopy (IS) measurements, [25][26][27] are used to investigate the ion migration process in PSCs. Kim et al. [25] carried out IS measurements on both (FAPbI 3 ) 0.875 (CsPbBr 3 ) 0.125 and MAPbI 3 films.

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“…In the vertical type devices, the interelectrode distance is small, thus vertical charge carrier transport is mainly limited by contact layers. Due to preferential orientation of grain boundaries, [85,86] this configuration enables devices with high-performance parameters especially response time and high sensitivity. In the lateral configuration devices, the spacing between electrodes is orders formed at interdigitate electrodes.…”

Section: Effects Of Grain Boundaries On the Performance Of Solar Cells Detectors And Ledsmentioning

confidence: 99%

The Role of Grain Boundaries in Charge Carrier Dynamics in Polycrystalline Metal Halide Perovskites

Gegevičius

Gulbinas

2021

Eur J Inorg Chem

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Boundaries of perovskite grains forming polycrystalline films are the most sensitive place for the formation of the defect states and accumulation of impurities. The intra-bandgap states located at the boundaries forming traps for charge carriers are commonly discussed as causing nonradiative carrier recombination and reducing carrier mobility. Grain boundaries (GB) may also disturb carrier motion by creating scattering centres and barriers, however, their role was less frequently considered. On the other hand, grain boundaries may also facilitate the splitting of exciton states and the generation of free charge carriers. Consequently, the grain boundaries are responsible or affect a wide range of perovskite properties and processes strongly influencing the performance of perovskite-based optoelectronic devices. Nevertheless, abundant literature data related to the properties of grain boundaries and their influence are highly controversial. In this minireview, we discuss the most importnat literature data related to the structure and properties of grain boundaries and their role in device performance.

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Grain Size Influences Activation Energy and Migration Pathways in MAPbBr₃ Perovskite Solar Cells

Cited by 91 publications

References 27 publications

Understanding the Role of Grain Boundaries on Charge‐Carrier and Ion Transport in Cs₂AgBiBr₆ Thin Films

Understanding the Role of Grain Boundaries on Charge‐Carrier and Ion Transport in Cs₂AgBiBr₆ Thin Films

Understanding the Influence of Cation and Anion Migration on Mixed‐Composition Perovskite Solar Cells via Transient Ion Drift

The Role of Grain Boundaries in Charge Carrier Dynamics in Polycrystalline Metal Halide Perovskites

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Grain Size Influences Activation Energy and Migration Pathways in MAPbBr3 Perovskite Solar Cells

Cited by 91 publications

References 27 publications

Understanding the Role of Grain Boundaries on Charge‐Carrier and Ion Transport in Cs2AgBiBr6 Thin Films

Understanding the Role of Grain Boundaries on Charge‐Carrier and Ion Transport in Cs2AgBiBr6 Thin Films

Understanding the Influence of Cation and Anion Migration on Mixed‐Composition Perovskite Solar Cells via Transient Ion Drift

The Role of Grain Boundaries in Charge Carrier Dynamics in Polycrystalline Metal Halide Perovskites

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Grain Size Influences Activation Energy and Migration Pathways in MAPbBr₃ Perovskite Solar Cells

Understanding the Role of Grain Boundaries on Charge‐Carrier and Ion Transport in Cs₂AgBiBr₆ Thin Films

Understanding the Role of Grain Boundaries on Charge‐Carrier and Ion Transport in Cs₂AgBiBr₆ Thin Films