Organic Cation Rotation and Immobilization in Pure and Mixed Methylammonium Lead-Halide Perovskites

Selig, Oleg; Sadhanala, Aditya; Müller, Christian; Lovrinčić, Robert; Chen, Zhuoying; Rezus, Y. L. A.; Frost, Jarvist M.; Jansen, Thomas L. C.; Bakulin, Artem A.

doi:10.1021/jacs.6b12239

Cited by 126 publications

(189 citation statements)

References 63 publications

(112 reference statements)

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“…Indeed, the cation–lattice interaction was recently concluded to be not significantly different for MAPbI 3 and FAPbI 3 . However, the role of hydrogen bonds between the organic cations and the lattice, the rotation of the cations itself with the almost identical timescales of cation rotation and carrier–phonon interaction, and the connection to polaron formation and initial carrier cooling are important question to be answered in order to fully elucidate the fundamental photophysical phenomena in lead‐halide perovskite solar cells …”

Section: Average Cooling Rates Obtained From the Temperature‐ And Excmentioning

confidence: 99%

Quantifying Polaron Formation and Charge Carrier Cooling in Lead‐Iodide Perovskites

et al. 2018

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Notwithstanding the success of lead-halide perovskites in emerging solar energy conversion technologies, many of the fundamental photophysical phenomena in this material remain debated. Here, the initial steps following photogeneration of free charge carriers in lead-iodide perovskites are studied, and timescales of charge carrier cooling and polaron formation, as a function of temperature and charge carrier excess energy, are quantified. It is found, using terahertz time-domain spectroscopy (THz-TDS), that the observed femtosecond rise in the photoconductivity can be described very well using a simple model of sequential charge carrier cooling and polaron formation. For excitation above the bandgap, the carrier cooling time depends on the charge carrier excess energy and lattice temperature, with cooling rates varying between 1 and 6 meV fs , depending on the cation. While carrier cooling depends on the cation, polaron formation occurs within ≈400 fs in CH NH PbI (MAPbI ), CH(NH ) PbI (FAPbI ), and CsPbI . Its formation time is independent of temperature between 160 and 295 K. The very similar polaron formation dynamics observed for the three perovskites points to the critical role of the inorganic lattice, rather than the cations, for polaron formation.

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Section: Average Cooling Rates Obtained From the Temperature‐ And Excmentioning

confidence: 99%

Quantifying Polaron Formation and Charge Carrier Cooling in Lead‐Iodide Perovskites

et al. 2018

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“…a) Structure of the PSCs based on CsPbI 3 QDs layers and (b) J–V curves of the CsPbI 3 QDs PSCs after different storage periods. Reproduced with permission . Copyright 2016, Science Publishing Group.…”

Section: Lead‐based I‐pvksmentioning

confidence: 99%

Inorganic Perovskite Solar Cells: A Rapidly Growing Field

et al. 2018

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Since the first report in 2009, organic-inorganic hybrid perovskite solar cells (OIH-PSCs) which have achieved the power conversion efficiencies (PCEs) over 22% have gathered interest in the scientific community. Such high PCEs achieved by low-cost solution-processed fabrication techniques are comparable to the traditional commercial solar cells. However, before practical applications, the main challenge that must be addressed is material stability. Replacing organic-inorganic hybrid perovskite (OIH-PVK) with inorganic perovskites (I-PVKs) in PSCs has been a promising resolution and up to now, much progress has been made. In this review, a systematic review on the most recent research and progress in inorganic PSCs (I-PSCs) is presented, which is divided into three parts according to material category (lead-based I-PVK, lead-free I-PVK, and perovskite-derived materials). Moreover, current challenges and future research directions are suggested from the aspects of material stability, synthesis methods, device structure and working mechanism.

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“…[26][27][28][29] Hence, it is possible to distinguish between three classes of vibrations which are vibrations of the PbI 6 octahedra (<150 cm −1 ), of the MA + cation (300-3000 cm −1 ) and vibrations between them (<130 cm −1 ). [26] While the vibrations of the PbI 6 octahedra were found to be predominantly responsible for the degree of dielectric screening in MAPbI 3 , [29] the MA + vibrations sensitively depend on changes in their stoichiometry, [30] crystal phase, and temperature, [27,31] and also impact the corresponding exciton binding energy. [11] Valuable insights into its electronic properties can be obtained not only from the temperature dependence of the PL linewidth but also from the variation in its intensity.…”

Section: Photoluminescencementioning

confidence: 99%

Impact of Structural Dynamics on the Optical Properties of Methylammonium Lead Iodide Perovskites

Panzer

Meier

et al. 2017

Advanced Energy Materials

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structure, [2] and changing the ratio of precursor compounds prior to the formation of the perovskite layer. [3] These approaches are based on modifying the crystallization process, for example, by controlling the composition of the precursor solution and by varying processing parameters. Such changes also led to major improvements in perovskite-based light-emitting devices within the last year. Initially, the current efficiencies were improved by optimizing the grain size to values below 100 nm, and by changing the precursor compound molar proportions. [4] More recently, efficient perovskite-based LEDs with external quantum efficiencies exceeding 10% were even obtained by expanding towards lower dimensional perovskite structures. [5] Different structures and dimensionalities resulted in altered charge-carrier dynamics affecting the radiative recombination efficiency. [5,6] By drawing strong correlations between structural properties and their electronic structure, major breakthroughs toward light-emitting devices or in photovoltaics could be achieved in very recent years. To a certain extent, this resembles the evolution in the field of organic semiconductors, where improved understanding of the interplay between morphological and electronic structure proved essential to facilitate the recent progress in organic photovoltaics, and the successful commercialisation of organic LED devices. Also, for hybrid perovskites the question of how crystal structure, shape, and grain size governs the electronic structure will remain an important topic in the future to further improve perovskite-based optoelectronic devices. Since the solution processability of hybrid perovskites enables easy tuning of material compositions, a large number of different hybrid perovskites were reported. For example, exchanging the organic cation can alter the crystal structure, shift phase transitions, as does formamidinium, or change further excited-state dynamics, as is happening with Cs or Ru. Furthermore, different halide anions change the optical and excited state properties. The optical bandgap can be changed from the UV to NIR region by replacing the halide from Cl to Br to I. Mixed-halide systems thereof even provide a way to gradually tune the respective bandgap. In fact, the recently reported, most stable and efficient perovskite solar cells (PSCs) are based on a highly optimized mixture of different anions and cations. [1,7] Nevertheless, the most investigated hybrid perovskite representative is the methylammonium lead iodide perovskite CH 3 NH 3 PbI 3 (MAPbI 3 ), which, in the meantime, has become Organolead halide perovskites have attracted a lot of attention over the recent years mostly due to their bright prospective application in photovoltaic devices. For further development, characterization of their physical properties plays a seminal role in order to gain an in-depth understanding of these mid-bandgap ionic semiconductors. Their unique optical and electronic properties are a result of their characteristic electronic stru...

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Organic Cation Rotation and Immobilization in Pure and Mixed Methylammonium Lead-Halide Perovskites

Cited by 126 publications

References 63 publications

Quantifying Polaron Formation and Charge Carrier Cooling in Lead‐Iodide Perovskites

Quantifying Polaron Formation and Charge Carrier Cooling in Lead‐Iodide Perovskites

Inorganic Perovskite Solar Cells: A Rapidly Growing Field

Impact of Structural Dynamics on the Optical Properties of Methylammonium Lead Iodide Perovskites

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