Resolving in-plane and out-of-plane mobility using time resolved microwave conductivity

Chattopadhyay, Shirsopratim; Kokenyesi, Robert S.; Hong, Mina; Watts, Lowell; Labram, John G.

doi:10.1039/d0tc00328j

Cited by 8 publications

(6 citation statements)

References 52 publications

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“…Preliminary results (Table S3) indicate that the ϕ∑μ value for (ACA)(MA)PbI 4 (ϕ∑μ = 0.014 cm 2 /(V s)) is lower than that for (BA) 2 PbI 4 (ϕ∑μ = 0.076 cm 2 /(V s)). Both 2D samples have values 1 order of magnitude lower than that of the 3D film sample (MA)PbI 3 (ϕ∑μ = 0.66 cm 2 /(V s)), for which the measured value is consistent with previous reports. , This is not unexpected, as the average connectivity, and hence mobility, in a random direction is anticipated to be higher in a 3D system than in a 2D system. Additionally, while the role played by excitons is unclear in these compounds, it likely that the ϕ value will be higher in a 3D system than in a 2D system.…”

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confidence: 89%

Layered Hybrid Lead Iodide Perovskites with Short Interlayer Distances

Mao

Morgan

et al. 2022

ACS Energy Lett.

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Layered hybrid perovskites comprise modular components that are individually highly tunable, resulting in materials with a range of structure and properties. In these layered materials, the usual assumption is of two-dimensional electronic behavior, because of the relatively large separations between the inorganic layers. Here, we report two layered hybrid lead iodide perovskites that possess unusually short interlayer distances: (IPA)2(MA)Pb2I7 and (ACA)(MA)PbI4 (IPA = iso-propylammonium, MA = methylammonium, ACA = acetamidinium). These compounds are prepared from mixing small organic cations, where they crystallize in the Ruddlesden-Popper type structure, and a structure with alternating cations in the interlayer space, respectively. The crystal structures are compared in detail with related structures, and electronic structures are analyzed using density-functional theory-based calculations. Time-resolved microwave conductivity measurements are employed to provide insight into charge transport in these compounds. This work exemplifies the unusual templating role of small organic cations in the layered halide compounds.

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confidence: 89%

Layered Hybrid Lead Iodide Perovskites with Short Interlayer Distances

Mao

Morgan

et al. 2022

ACS Energy Lett.

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“…33 We observe ultra-long charge carrier lifetimes in all methylammonium lead halide perovskites at low temperatures, with the values summarized in Table 1. The observed values are all larger than those found in earlier TRMCD studies, [35][36][37][38][39][40][41] which may be related to an improved sample quality in the present study.…”

Section: Resultscontrasting

confidence: 80%

Ultralong Charge Carrier Recombination Time in Methylammonium Lead Halide Perovskites

et al. 2022

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Due to their exceptional photovoltaic properties, metal halide perovskites (MHPs) are extensively studied for their potential applications in solar cells. In recent years, the power conversion efficiencies of MHPs-based solar cells rapidly increased from the initial few % towards more than 25 % for single-junction devices. Therefore, also taking into account their low costs and ease of manufacturing, MHPs-based solar cells have become the fastest-advancing photovoltaic technology. In this regard, much of the recent work has been dominated by absorber materials based on methylammonium MHPs, such as MAPbX 3 , where MA=CH 3 NH 3 and X=Cl, Br and I. Here, we present the results of contactless time-resolved photoconductivity measurements in an exceptionally wide range of temperatures of 4 to 290 K that were performed for the various crystalline forms of the three parent MAPbX 3 , i.e., MAPbCl 3 , MAPbBr 3 and MAPbI 3 . This approach was made possible by the use of a high quality-factor (Q) microwave resonator, which cooperated with a commercially available microwave bridge equipped with an automatic frequency control (AFC) and a helium gas-flow cryostat.The structural phase transitions from orthorhombic to tetragonal are found to drastically affect the transient photoconductivity signal and we also observe ultra-long charge carrier recombination times approaching 70 µs at low temperatures. The difference caused by morphology on the photophysical properties is supported by a marked difference between rapidly cooled (quenched) and slowly cooled samples. The sensitive technique also allowed to observe differences between samples with different morphologies and crystallite sizes.

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“…Furthermore, the mobility of the charge carriers, another key parameter of semiconductor materials, was also determined. We first evaluated the charge carrier dynamics with time-resolved microwave conductivity (TRMC), which is a noncontact method and can precisely reflect the photoconductivity of semiconductors. , Figure d shows the recorded TRMC decay of the D18 thin films, which exhibited an excellent TRMC signal after excitation with a nanosecond laser pulse. Compared with other disordered organic compounds, D18 exhibited a much stronger TRMC response, indicating superior charge generation and relatively high mobility.…”

Section: Results and Discussionmentioning

confidence: 99%

High-Performance Organic Phototransistors Based on D18, a High-Mobility and Unipolar Polymer

et al. 2021

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Organic optoelectronics has progressed excitingly in recent years, mainly due to the innovation of donor and acceptor systems. Organic photodetectors based on novel semiconductor materials and well-designed device architectures have also been reported with improved device performance. However, most of them were photodiodes, and it is challenging to integrate them into the well-established readout circuits. Organic phototransistors are mainly based on the hybrid strategy, composed of either hybrid films or multilayer device structures, which complicates charge transfer and charge transport. Most of the organic devices also suffer from poor stability. In this work, we introduce a recently developed p-type copolymer, D18, to fabricate high-performance phototransistors. D18 possesses excellent charge generation, high mobility, and unipolar charge transport, which fulfill the generic design rule of organic phototransistors. The optimized phototransistors based on D18 exhibited extremely low dark current (∼10 pA) and noise (∼10 fA/Hz 1/2 ), a high detectivity of 4 × 10 13 Jones, a swift response of <5 ms, and excellent device stability. We also demonstrated flexible phototransistors with decent performance metrics, indicating great potential for next-generation solutionprocessed photodetectors and flexible electronic devices.

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Resolving in-plane and out-of-plane mobility using time resolved microwave conductivity

Abstract:
A strategy is demonstrated to evaluate the carrier mobility in-plane and out-of-plane using contactless time resolved microwave conductivity.

Cited by 8 publications

References 52 publications

Layered Hybrid Lead Iodide Perovskites with Short Interlayer Distances

Layered Hybrid Lead Iodide Perovskites with Short Interlayer Distances

Ultralong Charge Carrier Recombination Time in Methylammonium Lead Halide Perovskites

High-Performance Organic Phototransistors Based on D18, a High-Mobility and Unipolar Polymer

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Resolving in-plane and out-of-plane mobility using time resolved microwave conductivity

Abstract: A strategy is demonstrated to evaluate the carrier mobility in-plane and out-of-plane using contactless time resolved microwave conductivity.

Cited by 8 publications

References 52 publications

Layered Hybrid Lead Iodide Perovskites with Short Interlayer Distances

Layered Hybrid Lead Iodide Perovskites with Short Interlayer Distances

Ultralong Charge Carrier Recombination Time in Methylammonium Lead Halide Perovskites

High-Performance Organic Phototransistors Based on D18, a High-Mobility and Unipolar Polymer

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Abstract:
A strategy is demonstrated to evaluate the carrier mobility in-plane and out-of-plane using contactless time resolved microwave conductivity.