Exciton-phonon interaction in PbI2 revealed by Raman and photoluminescence studies using excitation light overlapping the fundamental absorption edge

Baibarac, M.; Smaranda, Ion; Scocioreanu, M.; Mitran, Raul−Augustin; Enculescu, Monica; Galatanu, Magdalena; Baltog, I.

doi:10.1016/j.materresbull.2015.06.012

Cited by 28 publications

(22 citation statements)

References 40 publications

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“…In all the spectra three peaks are present at wavenumbers 96, 136 and 215 cm −1 as marked in the figure. All the peaks were identified as that originated from vibrational modes of PbI 2 comparing with the reported Raman peaks for this compound [17]. As mentioned earlier, PbI 2 exists in different polytypes in which the common form is 2H 8 Each plane of I and Pb atoms is an identical series of triangles or overlapping hexagons.…”

Section: Raman Spectroscopymentioning

confidence: 52%

“…The band at 96 cm −1 corresponds to the A lg mode, and that at 136 cm −1 may be due to the resonant optical excitation of the PbI 2 molecules. The broadband at 215 cm −1 was also reported as a characteristic peak of PbI 2 [17]. The well-defined principal band at 96 cm −1 for both the thin film samples implies their good crystalline nature in correlation with the well-defined XRD peaks.…”

Section: Raman Spectroscopymentioning

confidence: 71%

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Growth and properties of lead iodide thin films by spin coating

et al. 2016

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Abstract. In this study, lead iodide (PbI 2 ) thin films were deposited on glass substrates by spin coating a solution of 0.2 M PbI 2 dissolved in dimethylformamide, varying the deposition time and the spin speed. The thickness of the thin films decreased with increase in spin speed and deposition time, as examined by profilometry measurements. The structure, morphology, optical and electrical properties of the thin films were analysed using various techniques. X-ray diffraction patterns revealed that the thin films possessed hexagonal structures. The thin films were grown highly oriented to [001] direction of the hexagonal lattice. Raman peaks detected at 96 and 136 cm −1 were corresponding to the characteristic vibration modes of PbI 2 . The X-ray photoelectron spectroscopy detected the presence of Pb and I with core level binding energies corresponding to that in PbI 2 . Atomic force microcopy showed smooth and compact morphology of the thin films. From UV-Vis transmittance and reflectance spectral analysis, the bandgap of the thin films ∼2.3 eV was evaluated. The dark conductivity of the thin films was computed and the value decreased as the deposition time and spin speed increased.

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Section: Raman Spectroscopymentioning

confidence: 52%

Section: Raman Spectroscopymentioning

confidence: 71%

Growth and properties of lead iodide thin films by spin coating

et al. 2016

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“…The main observations based on the Raman effect that were not fully understood regarding the Fröhlich exciton–phonon interaction were based on the unexplained different enhancements of the Raman lines in the Stokes and anti‐Stokes branches and also the distinct strength of the exciton–phonon interaction in various morphological forms. These aspects have been explained based on a nonlinear optical process in PbI 2 .…”

Section: Introductionmentioning

confidence: 99%

Exciton-phonon interactions in the Cs₃Bi₂I₉crystal structure revealed by Raman spectroscopic studies

Nila¹,

Baibarac²,

Matea³

et al. 2016

Phys. Status Solidi B

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The enhancement of the Raman scattering in Cs3Bi2I9 is evaluated by the ratio IT/I300 K between the relative intensities of the Raman line peaked at 146 cm−1, when the spectra are recorded in the temperature range of 88–300 K, as a signature of exciton–phonon interactions. In the resonant and nonresonant conditions, excitation wavelengths 476, 561, and 660 nm, respectively, are used in order to overlap with great accuracy the bands disclosed by diffuse reflection, photoconductivity (PC), photoluminescence (PL), and photoluminescence excitation (PLE) spectra. Based on the experimental analyses, the strength of exciton–phonon interaction is dependent on the defects in the crystal and the type–range interaction of the excitations in an independent Bi2I93− cluster. The noticeable PL band, attributed to excitons trapped on different stacking faults, manifests some defects in crystal that diminish the movement of excitons. This effect significantly decreases the overlaps of excitons with the phonons, resulting in a reduced exciton–phonon coupling.

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“…We also checked the PL variation in oxygen atmosphere mixed with H 2 O vapor, as shown in Figure S8 . The photo-induced segregation even cannot catch up with photo-degradation processes, and finally, the whole perovskite phase turned into lead halide phase ( Baibarac et al., 2015 ). For the fact that CsPbI 3 perovskite was thermodynamically unfavorable under room temperature and very prone to exhibit phase transition in ambient atmosphere ( Eperon et al., 2015 ; Kulbak et al., 2015 ; Luo et al., 2016 ; Yunakova et al., 2012 ), the photo-induced phase segregation was almost masked owing to the fast disappearance of iodine-rich phase in the mixed atmosphere of oxygen and H 2 O.…”

Section: Resultsmentioning

confidence: 99%

Inhibition of Phase Segregation in Cesium Lead Mixed-Halide Perovskites by B-Site Doping

Hong

Zhao

et al. 2020

iScience

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Summary The emergence of all-inorganic halide perovskites has shown great potential in photovoltaic and optoelectronic devices. However, the photo-induced phase segregation in lead mixed-halide perovskites has severely limited their application. Herein, by real-time monitoring the photoluminescence (PL) spectra of metal mixed-halide perovskites under light irradiation, we found that the photo-induced phase transition can be significantly inhibited by B-site doping. For pristine mixed-halide perovskites, an intermediate phase of CsPbBr x I 3-x can only be stabilized under low excitation power. After introducing Sn 2+ ions, such intermediate phase can be stabilized in nitrogen atmosphere under high excitation power and phase segregation can be started after the exposure in oxygen due to oxidization of Sn 2+ . Replacing Sn 2+ by Mn 2+ can further improve the intermediate phase's tolerance to oxygen proving that B-site doping in perovskites structure by Sn 2+ or Mn 2+ could effectively minimize the light-induced phase segregation and promote them to serve as promising candidates in photovoltaic and light-emitting devices.

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Exciton-phonon interaction in PbI2 revealed by Raman and photoluminescence studies using excitation light overlapping the fundamental absorption edge

Cited by 28 publications

References 40 publications

Growth and properties of lead iodide thin films by spin coating

Growth and properties of lead iodide thin films by spin coating

Exciton-phonon interactions in the Cs₃Bi₂I₉crystal structure revealed by Raman spectroscopic studies

Inhibition of Phase Segregation in Cesium Lead Mixed-Halide Perovskites by B-Site Doping

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Exciton-phonon interaction in PbI2 revealed by Raman and photoluminescence studies using excitation light overlapping the fundamental absorption edge

Cited by 28 publications

References 40 publications

Growth and properties of lead iodide thin films by spin coating

Growth and properties of lead iodide thin films by spin coating

Exciton-phonon interactions in the Cs3Bi2I9crystal structure revealed by Raman spectroscopic studies

Inhibition of Phase Segregation in Cesium Lead Mixed-Halide Perovskites by B-Site Doping

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Exciton-phonon interactions in the Cs₃Bi₂I₉crystal structure revealed by Raman spectroscopic studies