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The Photochemical Stability of PbI[sub.2] and PbBr[sub.2]: Optical and XPS and DFT Studies

We investigated the photochemical stability of PbX[sub.2] (X = I and Br) halides by optical and X-ray photoelectron spectroscopy (XPS). The optical absorbance displayed a strong reduction for PbI2 with light soaking and permanent behavior for PbBr[sub.2]. The XPS survey spectra showed a sharp drop i...

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Bibliographic Details
Published in:Coatings (Basel) 2023-04, Vol.13 (4)
Main Authors: Zhidkov, Ivan S, Akbulatov, Azat F, Poteryaev, Alexander I, Kukharenko, Andrey I, Rasmetyeva, Alexandra V, Frolova, Lyubov A, Troshin, Pavel A, Kurmaev, Ernst Z
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Language:English
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Summary:We investigated the photochemical stability of PbX[sub.2] (X = I and Br) halides by optical and X-ray photoelectron spectroscopy (XPS). The optical absorbance displayed a strong reduction for PbI2 with light soaking and permanent behavior for PbBr[sub.2]. The XPS survey spectra showed a sharp drop in the I:Pb ratio for PbI[sub.2] from 1.63 to 1.14 with exposure time from 0 to 1000 h while for PbBr2, it remains practically unchanged (1.59-1.55). The measurements of the XPS Pb 4f and Pb 5d spectra have shown the partial photolysis of PbI[sub.2] with the release of metallic lead whereas PbBr[sub.2] demonstrated remarkable photochemical stability. According to the density functional theory (DFT), calculations of the metal and iodide vacancy formation energies for PbBr[sub.2] are higher than for PbI[sub.2] which confirms the better stability to light soaking. The high photochemical stability of PbBr[sub.2] means that it can be used as excess under MAPbBr[sub.3] perovskite synthesis to improve not only the power conversion efficiency but also stability to light soaking.
ISSN:2079-6412
2079-6412
DOI:10.3390/coatings13040784