Optical properties of organic–inorganic hybrid films prepared by the two-step growth process

Kitazawa, Nobuaki; Yaemponga, Dhebbajaji; Aono, Masami; Watanabe, Yoshihisa

doi:10.1016/j.jlumin.2009.04.023

Cited by 15 publications

(12 citation statements)

References 23 publications

(32 reference statements)

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“…3d, e). Close to the continuum onset and in our experimental energy range, the optical transitions in RPPs at energies above E G have been assigned 11,14,50 to transitions between the Pb(6 s )-I(5 p ) states in the valence band and Pb(6 p ) states in the conduction band 20,51 . The absorption features A, B and C can be understood as transitions between valence and conduction bands overlapping with the continuum of states from the band-edge exciton.…”

Section: Resultssupporting

confidence: 56%

Scaling law for excitons in 2D perovskite quantum wells

et al. 2018

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Ruddlesden–Popper halide perovskites are 2D solution-processed quantum wells with a general formula A2A’n-1MnX3n+1, where optoelectronic properties can be tuned by varying the perovskite layer thickness (n-value), and have recently emerged as efficient semiconductors with technologically relevant stability. However, fundamental questions concerning the nature of optical resonances (excitons or free carriers) and the exciton reduced mass, and their scaling with quantum well thickness, which are critical for designing efficient optoelectronic devices, remain unresolved. Here, using optical spectroscopy and 60-Tesla magneto-absorption supported by modeling, we unambiguously demonstrate that the optical resonances arise from tightly bound excitons with both exciton reduced masses and binding energies decreasing, respectively, from 0.221 m0 to 0.186 m0 and from 470 meV to 125 meV with increasing thickness from n equals 1 to 5. Based on this study we propose a general scaling law to determine the binding energy of excitons in perovskite quantum wells of any layer thickness.

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Section: Resultssupporting

confidence: 56%

Scaling law for excitons in 2D perovskite quantum wells

et al. 2018

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“…Specifically, a second peak appears with larger Stokes shift and is particularly prominent in the C1 compound. This band, which has a much longer lifetime (∼10–100 ns depending on the organic component) than the free exciton emission (∼1 ns) (Figure D) has been assigned to recombination of triplet excitons formed through intersystem crossing from singlet exciton states. − Such typically forbidden excitonic transitions are weakly allowed through spin–orbit interactions . Differences in excitonic resonances between the two related compounds have been ascribed to discrepancies in the organic–inorganic interface, where triplet excitons have been reported to form. , Similar Stokes-shifted PL bands may also stem from bound exciton states depending on the nature of the organic component .…”

Section: Linear Absorption and Photoluminescencementioning

confidence: 94%

Intriguing Optoelectronic Properties of Metal Halide Perovskites

2016

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A new chapter in the long and distinguished history of perovskites is being written with the breakthrough success of metal halide perovskites (MHPs) as solution-processed photovoltaic (PV) absorbers. The current surge in MHP research has largely arisen out of their rapid progress in PV devices; however, these materials are potentially suitable for a diverse array of optoelectronic applications. Like oxide perovskites, MHPs have ABX stoichiometry, where A and B are cations and X is a halide anion. Here, the underlying physical and photophysical properties of inorganic (A = inorganic) and hybrid organic-inorganic (A = organic) MHPs are reviewed with an eye toward their potential application in emerging optoelectronic technologies. Significant attention is given to the prototypical compound methylammonium lead iodide (CHNHPbI) due to the preponderance of experimental and theoretical studies surrounding this material. We also discuss other salient MHP systems, including 2-dimensional compounds, where relevant. More specifically, this review is a critical account of the interrelation between MHP electronic structure, absorption, emission, carrier dynamics and transport, and other relevant photophysical processes that have propelled these materials to the forefront of modern optoelectronics research.

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“…One is to concentrate carriers in a small size, thus significantly increasing the charge‐carrier densities to produce high PLQYs even at low excitation intensity . The other one is to enable the formation of free exciton due to the enhanced exciton binding energy, which makes the radiative recombination in LD perovskites dominated by free exciton emission and thus further ensures the high PLQYs at low excitation fluence. Nevertheless, it is worth mentioning that the photoluminescence in LD perovskites originating from free‐carrier rather than exciton emission has also been reported in certain cases …”

Section: Fundamentals Of Optical Process In Metal Halide Perovskitesmentioning

confidence: 99%

Properties of Excitons and Photogenerated Charge Carriers in Metal Halide Perovskites

2019

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their great success in photovoltaics (PVs), with a phenomenally rapid rise of the power conversion efficiency (PCE) from 3.8% [1] to over 23% [2,3] in the past few years. Such high PCE of perovskite solar cells has been ascribed to the ultralong carrier lifetimes, [4][5][6][7][8] long carrier diffusion lengths, [9][10][11][12][13][14] and the extraordinarily defect tolerance. [15][16][17] Following the success of perovskites in photovoltaics, research on light-emitting diodes (LEDs), [18,19] amplified spontaneous emission (ASE) or lasers, [20][21][22][23][24] and photodetectors [25][26][27][28][29] have also gained substantial interests. Meanwhile, the rapid progress of MHPs on various applications spurred a flurry of photophysical studies in order to understand the origin of the high performance of these devices, of which the nature of the photoexcitation species has been mostly debated. [5,22,30,31] Since the photoexcitation states near the bandgap affect the key processes such as charge transport and light emission of optoelectronic devices, there is no doubt that the investigation of electronic excitations near the optical band edge is crucial for MHPs. Such knowledge is essential not only for understanding the correlation between the fundamental photophysics and device performances, but also offering a guideline for their further applications with improved performances. Generally, there are two kinds of photoexcitations near the band edge for direct bandgap semiconductors: free carriers and excitons. Exciton binding energy that reflects the Coulomb interaction strength between photoexcited electrons and holes determines the balance of the populations between the two species. Typically, inorganic semiconductors are free-carrier materials with the exciton binding energies only in few meV at room temperature and their excited states being populated principally by free carriers. While organic semiconductors are excitonic materials with the exciton binding energies in hundreds of meV and thus excitons prevailing in the excited states. Whereas, MHPs that combine some merits of organic and inorganic semiconductors seem to stand for an exotic class of semiconductors between these two limiting cases, with the experimentally determined exciton binding energy varying in a wide range of 2 to more than 50 meV for the prototype perovskite MAPbI 3 . [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48] Such large variations of the exciton binding energies reported for MHPs give rise to a strongly debated question, that is, whether free carriers or excitons are generated upon photoexcitation? In other words, what is the nature of the photoexcitation species Metal halide perovskites (MHPs) have recently attracted great attention from the scientific community due to their excellent photovoltaic performance as well as their tremendous potential for other optoelectronic applications such as light-emitting diodes, lasers, and photodetectors. Despite the rapid progress in device applications, a solid unders...

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Optical properties of organic–inorganic hybrid films prepared by the two-step growth process

Cited by 15 publications

References 23 publications

Scaling law for excitons in 2D perovskite quantum wells

Scaling law for excitons in 2D perovskite quantum wells

Intriguing Optoelectronic Properties of Metal Halide Perovskites

Properties of Excitons and Photogenerated Charge Carriers in Metal Halide Perovskites

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