Interlayer interaction and optical properties of layer semiconductors: 2H and 4H polytypes of PbI<sub>2</sub>

Doni, E.; Grosso, Giuseppe; Harbeke, G.; Meier, Edi; Tosatti, Erio

doi:10.1002/pssb.2220680214

Cited by 47 publications

(8 citation statements)

References 14 publications

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“…Absorption peaks at 2.5 eV are also observed in our measurement, which can be attributed to another direct transition in CH 3 NH 3 PbI 3 [18]. It has been reported that PbI 2 has a sharp transition peak at 2.5 eV, while the CH 3 NH 3 PbI 3 peak is broad [42]. The deceasing broadening term C 2 indicates that a higher level of hydration water results in a higher content of PbI 2 in perovskite films.…”

Section: Resultssupporting

confidence: 78%

Influence of hydration water on CH_3NH_3PbI_3 perovskite films prepared through one-step procedure

Wang¹,

Yuan²,

Li³

et al. 2016

Opt. Express

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Organic-inorganic perovskites were fabricated through a one-step procedure with different levels of hydration water in precursor solutions. The optical properties of CH₃NH₃PbI₃ films were investigated through spectroscopic ellipsometry and photoluminescence measurements. With the measured optical constants, the efficiency limit of perovskite solar cells is predicted with a detailed balance model. By comparing the optical measurement to that of planar heterojunction solar cells, we conclude that the radiative efficiency and porosity of the perovskite film significantly influence the performance of perovskite solar cells. An optimized hydration-water concentration is obtained for the 3CH₃NH₃I:1PbAc₂•xH₂O precursor solution. The results can provide guidance for further optimization of the device performance of perovskite solar cells by utilizing hydration water.

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Section: Resultssupporting

confidence: 78%

Influence of hydration water on CH_3NH_3PbI_3 perovskite films prepared through one-step procedure

Wang¹,

Yuan²,

Li³

et al. 2016

Opt. Express

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“…PbI 2 is a direct transition semiconductor [77,78], although the α values near E g ~ 2.0 eV are very low [75,79]. A sharp optical transition at 2.5 eV in PbI 2 has been reported to be excitonic [78,80] and the transition energy of this peak is close to that of a CH 3 NH 3 PbI 3 peak observed in a similar energy region. However, the PbI 2 absorption peak at 2.5 eV is quite sharp, while the CH 3 NH 3 PbI 3 peak is very broad, suggesting that the origins of these transitions are different.…”

Section: Dft Calculationmentioning

confidence: 96%

Optical Transitions in Hybrid Perovskite Solar Cells: Ellipsometry, Density Functional Theory, and Quantum Efficiency Analyses forCH3NH3PbI3

et al. 2016

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Light-induced photocarrier generation is an essential process in all solar cells, including organic-inorganic hybrid (CH 3 NH 3 PbI 3 ) solar cells, which exhibit a high short-circuit current density (J sc ) of approximately 20 mA/cm 2 . Although the high J sc observed in the hybrid solar cells relies on strong electron-photon interaction, the optical transitions in the perovskite material remain unclear. Here, we report artifact-free CH 3 NH 3 PbI 3 optical constants extracted from ultra-smooth perovskite layers without air exposure and assign all the optical transitions in the visible/ultraviolet region unambiguously based on density functional theory (DFT) analysis that assumes a simple pseudo-cubic crystal structure. From the self-consistent spectroscopic ellipsometry analysis of the ultra-smooth CH 3 NH 3 PbI 3 layers, we find that the absorption coefficients of CH 3 NH 3 PbI 3 (α = 3.8 × 10 4 cm −1 at 2.0 eV) are comparable to those of CuInGaSe 2 and CdTe, and high α values reported in earlier studies are overestimated seriously by extensive surface roughness of CH 3 NH 3 PbI 3 layers. The polarization-dependent DFT calculations show that CH 3 NH 3 + interacts strongly with the

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“…Figure a shows the 2H‐polytype PbI 2 structure, in which the Pb atoms are surrounded by six I atoms and then forms an octahedral [PbI 6 ] 4− unit. The [PbI 6 ] 4− layers is bounded by weak vdW interactions with separation of 0.698 nm . In general, the unit cell of PbI 2 contains one Pb atom and two I atoms, where Pb atom occupies the top corner and I atoms locate at quarter positions in the lattice (Figure S1, Supporting Information).…”

mentioning

confidence: 99%

Low Threshold Fabry–Pérot Mode Lasing from Lead Iodide Trapezoidal Nanoplatelets

Zhong

Wei

Liu

et al. 2018

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Lead Iodide (PbI ) is a layered semiconductor with direct band gap holding great promises in green light emission and detection devices. Recently, PbI planar lasers are demonstrated using hexagonal whispering-gallery-mode microcavities, but the lasing threshold is quite high. In this work, lasing from vapor phase deposition derived PbI trapezoidal nanoplatelets (NPs) with threshold that is at least an order of magnitude lower than the previous value is reported. The growth mechanism of the trapezoidal NPs is explored and attributed to the synergistic effects of van der Waals interactions and lattice mismatching. The lasing is enabled by the population inversion of n = 1 excitons and the optical feedback is provided by the Fabry-Pérot oscillation between the side facets of trapezoidal NPs. The findings not only advance the understanding of growth and photophysics mechanism of PbI nanostructures but also provide ideas to develop low threshold ultrathin lasers.

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Interlayer interaction and optical properties of layer semiconductors: 2H and 4H polytypes of PbI₂

Cited by 47 publications

References 14 publications

Influence of hydration water on CH_3NH_3PbI_3 perovskite films prepared through one-step procedure

Influence of hydration water on CH_3NH_3PbI_3 perovskite films prepared through one-step procedure

Optical Transitions in Hybrid Perovskite Solar Cells: Ellipsometry, Density Functional Theory, and Quantum Efficiency Analyses forCH3NH3PbI3

Low Threshold Fabry–Pérot Mode Lasing from Lead Iodide Trapezoidal Nanoplatelets

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Interlayer interaction and optical properties of layer semiconductors: 2H and 4H polytypes of PbI2

Cited by 47 publications

References 14 publications

Influence of hydration water on CH_3NH_3PbI_3 perovskite films prepared through one-step procedure

Influence of hydration water on CH_3NH_3PbI_3 perovskite films prepared through one-step procedure

Optical Transitions in Hybrid Perovskite Solar Cells: Ellipsometry, Density Functional Theory, and Quantum Efficiency Analyses forCH3NH3PbI3

Low Threshold Fabry–Pérot Mode Lasing from Lead Iodide Trapezoidal Nanoplatelets

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Interlayer interaction and optical properties of layer semiconductors: 2H and 4H polytypes of PbI₂