Magnetoabsorption of the lowest exciton in perovskite-type compound (CH3NH3)PbI3

Hirasawa, Masahiro; Ishihara, Teruya; Goto, T.; Uchida, K.; Miura, N.

doi:10.1016/0921-4526(94)91130-4

Cited by 420 publications

(416 citation statements)

References 7 publications

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“…The question as to which optically excited species may couple to the THz probe pulse, either excitons or free charge-carriers has been addressed several times in earlier reports. [ 17,18,[39][40][41][42] We note that for MAPbI 3 the sole response to the THz conductivity probe has already been shown to be that of a free-charge carrier density, as inferred from the Drude shape of the conductivity spectra. [ 17,18 ] Here we also report highly similar Drude conductivity spectra for FAPbBr 3 (see the Supporting Information), which suggests that excitonic effects are negligible at room temperature for these mixed I/Br materials.…”

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confidence: 69%

Charge‐Carrier Dynamics and Mobilities in Formamidinium Lead Mixed‐Halide Perovskites

et al. 2015

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by at least four orders of magnitude. [ 17,18 ] MAPbI 3 also appears to exhibit only shallow trap-levels and although the grain boundaries have recently been shown to induce nonradiative decay, [ 19 ] regions only a few tens of nm away from the grain boundaries appear to be unaffected. [ 20,21 ] Furthermore, low Urbach energies, which are extracted from near band edge optical absorption measurements and serve as a benchmark for crystalline phase disorder, indicate low disorder and sharp band edges for lead tri-halide perovskites (15-23 meV). [ 22,23 ] All of these properties contribute to high open-circuit voltages, long charge-carrier lifetimes, and micrometer diffusion lengths, which are crucial for planar-hetero junction photovoltaics. [ 1,24 ] Nonetheless, these parameters are also expected to depend on the infl uence of crystallization condition on perovskite morphology in fabricated fi lms. [ 25 ] A distinct benefi t of organic-inorganic perovskite materials (e.g., over silicon) is that their bandgap can be tuned relatively easily with chemical composition, allowing attractive coloration and multijunction or tandem cell designs. For example, changing the metal cation at the M site from Pb 2+ to the less toxic Sn 2+ to form CH 3 NH 3 SnI 3 shifts the optical bandgap from 1.55 to 1.3 eV into the range of the "ideal" single-junction solar cell bandgap between 1.1 and 1.4 eV. [ 26,27 ] However, stability issues arising from the oxidation of tin have so far prevented widespread use. Alternatively, tuning the size of the A site cation has been proven to change optical and electronic properties of the perovskite and to signifi cantly infl uence solar cell performance. [ 28 ] Replacing MA in MAPbI 3 by the larger cation formamidinium HC(NH 2 ) 2 + (FA) was found to decrease the bandgap from 1.57 to 1.48 eV, [29][30][31] yield long photoluminescence (PL) lifetimes, high PCEs, [ 28 ] and lower recombination and device hysteresis. [ 32 ] Highest PCEs of 20.1% have been reported [12][13][14] to date for solar cells based on FAPbI 3 making this an attractive system to explore. In addition, the gradual replacement of the MA cation by FA through the fi lm was shown to create a mixed cation-lead-iodide PSC allowing for energetic gradients. [ 33 ] However, mixing of the halide component in the perovskite offers the fi nest tuning of the optical properties of the perovskite fi lm. Here, the mixed organic lead iodide/bromide system has recently gained strong interest for application in PSCs. [ 11,28 ] By changing the ratio between bromide and iodide (at the X site anion), the bandgap can be tailored between 1.55 eV (MAPbI 3 ) and 2.3 eV (MAPbBr 3 ), which results in the coverage of much of the visible spectrum and paves the way for the development of tandem solar cells. [ 11 ] In addition to MAPb(Br y I 1-y ) 3 , its formamidinium relative FAPb(Br y I 1-y ) 3 has been explored. [ 28 ] Most fractional mixtures of FAPb(Br y I 1-y ) 3 were found to be crystalline, with the exception of the region between y = 0.3 and Recent year...

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Charge‐Carrier Dynamics and Mobilities in Formamidinium Lead Mixed‐Halide Perovskites

et al. 2015

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“…The measured dielectric constant of the bulk material is roughly ∼3. 23,30,50 In NSs, however, the dielectric surroundings are strongly affected by the presence of the substrate on the one side of the layer and vacuum on the other, as reflected in the strong decrease of the asymptotic value to approach the average of the dielectric constants of vacuum/air and fused silica (Fig.4(f)− dashed line). This effect of the dielectric screening is more pronounced for the higher excited states and is the main reason for the overall increase of the binding energy.…”

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confidence: 99%

Excitons in ultrathin organic-inorganic perovskite crystals

et al. 2015

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We demonstrate the formation of large sheets of layered organic-inorganic perovskite (OIPC) crystals, as thin as a single unit cell, prepared by mechanical exfoliation. The resulting 2D OIPC nano sheets of 2.4 nm thickness are direct semiconductors with an optical band gap of 2.4 eV. They exhibit unusually strong light-matter interaction with an optical absorption as high as 25% at the main excitonic resonance, as well as bright photoluminescence. We extract an exciton binding energy of 490 meV from measurement of the series of excited exciton states. The properties of the excitons are shown to be strongly influenced by the changes in the dielectric surroundings. The environmental sensitivity of these ultrathin OIPC sheets is further reflected in the strong suppression of a thermally driven phase transition present in the bulk crystals.

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“…In fact, the comparison between the crystal radii measured by HRTEM and the reported estimated values of Bohr radius (R B ≈ 3 nm), [18][19][20][21][22] …”

Section: Doi: 101002/adom201601087mentioning

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Strong Quantum Confinement and Fast Photoemission Activation in CH₃NH₃PbI₃ Perovskite Nanocrystals Grown within Periodically Mesostructured Films

Anaya

Rubino

Rojas

et al. 2017

Advanced Optical Materials

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CommuniCation(1 of 7) 1601087 synthesis of PbI 2 nanocrystals and their subsequent reaction with CH 3 NH 3 I 3 to produce the corresponding organic-inorganic lead halide quantum dots. [4] More recently, powders of porous silica exhibiting a 2D hexagonal mesopore structure have been used as templates to synthesize MAPbI 3 nanocrystals. [14,15] This approach proved to be suitable to attain bright and stable emission whose spectrum could be controlled by the average pore size of the matrix. However, most applications foreseen for hybrid perovskites require the use of thin films of high optical quality, as well as versatility regarding the composition of the scaffold employed. In order to achieve this goal, mesostructures with geometries other than the hexagonal one previously employed to host perovskite nanocrystals must be used, since the characteristic tubular channels tend to lie parallel to the substrate when the porous material is shaped as a film, becoming inaccessible from the top surface. This prevents their infiltration with perovskite precursors. Very recently, MAPbI 2 X (X = Cl, Br, I) compounds have been synthesized inside metal organic framework films, [16] but no control over the size and optical properties of MAPbI 3 was demonstrated.In this Communication, we demonstrate a synthetic route to obtain stabilized MAPbI 3 nanocrystals embedded in thin metal oxide films that display well-defined and adjustable quantum confinement effects over a wide range of 0.34 eV. Mesostructured TiO 2 and SiO 2 films displaying an ordered 3D pore network are prepared by evaporation induced self-assembly of a series of organic supramolecular templates in the presence of metal oxide precursors. The pores in the inorganic films obtained after thermal annealing are then used as nanoreactors to synthesize MAPbI 3 crystallites with narrow size distribution and average radius comprised between 1 and 4 nm, depending on the template of choice. Both the static and dynamic photoemission properties of the ensemble display features distinctive of the regime of strong quantum confinement. Photoemission maps demonstrate that the spectral and intensity properties of the luminescence extracted from the perovskite quantum dot loaded films are homogeneous over squared centimeters areas. In addition, the photoemission stationary state is reached 10 4 times faster than in a MAPbI 3 solid film. One of the most versatile strategies to tune the optical properties of a semiconductor consists in reducing its size until it becomes of the order of the exciton Bohr radius and quantum confinement effects arise. [1] Different methods have been developed to try to controllably diminish the size of methyl ammonium lead halide (MAPbX 3 , X = Cl, Pb, I) crystals, [2][3][4][5][6][7] motivated by the interest these perovskites generate in the field of optoelectronics. [8][9][10][11][12] Efforts in obtaining dispersions of hybrid organic-inorganic perovskite nanocrystals for optoelectronic applications have mainly focused on MAPbBr 3 and MAPbBr x I 3-x , a...

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Magnetoabsorption of the lowest exciton in perovskite-type compound (CH3NH3)PbI3

Cited by 420 publications

References 7 publications

Charge‐Carrier Dynamics and Mobilities in Formamidinium Lead Mixed‐Halide Perovskites

Charge‐Carrier Dynamics and Mobilities in Formamidinium Lead Mixed‐Halide Perovskites

Excitons in ultrathin organic-inorganic perovskite crystals

Strong Quantum Confinement and Fast Photoemission Activation in CH₃NH₃PbI₃ Perovskite Nanocrystals Grown within Periodically Mesostructured Films

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Magnetoabsorption of the lowest exciton in perovskite-type compound (CH3NH3)PbI3

Cited by 420 publications

References 7 publications

Charge‐Carrier Dynamics and Mobilities in Formamidinium Lead Mixed‐Halide Perovskites

Charge‐Carrier Dynamics and Mobilities in Formamidinium Lead Mixed‐Halide Perovskites

Excitons in ultrathin organic-inorganic perovskite crystals

Strong Quantum Confinement and Fast Photoemission Activation in CH3NH3PbI3 Perovskite Nanocrystals Grown within Periodically Mesostructured Films

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Strong Quantum Confinement and Fast Photoemission Activation in CH₃NH₃PbI₃ Perovskite Nanocrystals Grown within Periodically Mesostructured Films