Removal of oxidic impurities for the growth of high purity lead iodide single crystals

Tonn, J.; Matuchová, M.; Danilewsky, A.N.; Cröll, A.

doi:10.1016/j.jcrysgro.2015.01.024

Cited by 12 publications

(11 citation statements)

References 30 publications

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“…As presented in Figure f, the PbI 2 SC underwent almost no weight loss before 400 °C. This is consistent with the results reported in the literature. − TiO 2 xerogels underwent a 26.5% weight loss in two steps (Figure S5). The first was at 107 °C and was due to the evaporation of absorbed water and ethanol.…”

supporting

confidence: 92%

PbI₂–TiO₂ Bulk Heterojunctions with Long-Range Ordering for X-ray Detectors

Wen

Liu

et al. 2021

J. Phys. Chem. Lett.

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High-performance X-ray detectors are usually based on single crystals, due to the long-range ordering and hence outstanding electronic properties. On the other hand, bulk heterojunctions (BHJs) that can effectively enhance photogenerated exciton dissociation are widely used for photodetectors. The benefits of both spur investigation into how to combine these two strategies to enhance X-ray detection. Here, TiO 2 networks are incorporated into PbI 2 crystals to form interpenetrating type II heterojunctions, namely BHJs. These BHJs exhibit long-range ordering in molecular packing similar to that of single crystals. Compared with single crystals, the long-range ordered BHJs facilitate the separation of photogenerated electrons and holes to inhibit recombination, extend the mobility lifetime product by 6.4 times, and consequently improve X-ray sensitivity by 5.8 times. Hence, this work provides a new strategy using gel-grown crystals to fabricate highperformance X-ray detectors as well as a new platform for studying the behavior of X-raygenerated carriers in BHJs with long-range ordering.

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supporting

confidence: 92%

PbI₂–TiO₂ Bulk Heterojunctions with Long-Range Ordering for X-ray Detectors

Wen

Liu

et al. 2021

J. Phys. Chem. Lett.

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“…Additionally, integration of the H 2 O peak before and after recrystallization reveals the H 2 O in the PbI 2 are relatively low1–2 orders of magnitude less than the original H 2 O content of as-received, anhydrous dimethylsulfoxide (DMSO)- d 6 (∼0.02 M) despite being stored and only opened in a N 2 glovebox (see Table S3). This suggests negligible water was introduced from the recrystallization, likely due to the non-hygroscopic nature of PbI 2 , and the largest source of water in our perovskite processing may be unavoidable due to the hygroscopic N , N ′-dimethlyformamide and DMSO solvents.…”

Section: Resultsmentioning

confidence: 99%

“…We found that iodide substoichiometry (I/Pb ratio < 2) was largely due to substitution of iodide by oxygen-containing anions, including hydroxide (OH − ), proposed previously, 11 as well as acetate (OAc) unambiguously identified in the lowest quality PbI 2 examined here. Oxidic impurities are notoriously difficult to remove from Pb halides, 19 but reducing their concentration has been shown to have a positive effect on perovskite devices. 11 In contrast, the high-quality PbI 2 sources investigated displayed relatively low concentrations of oxidic anion impurities.…”

Section: ■ Introductionmentioning

confidence: 99%

Analytical Evaluation of Lead Iodide Precursor Impurities Affecting Halide Perovskite Device Performance

Kerner

Christensen

Harvey

et al. 2022

ACS Appl. Energy Mater.

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Mirroring established semiconductor technologies, using higher quality reagents to synthesize halide perovskite materials results in improved optoelectronic performance. In this study, we selected five different commercial PbI 2 sources of various purities and fabricated solar cells in three different perovskite composition-device architecture combinations. In all cases, we observed similar device performance correlations to the PbI 2 reagent source across the different processing recipes and architectures. We then employed a suite of analytical characterization techniques to determine the identity and concentration of impurities within the PbI 2 reagents that affected the device performance trends. Many impurities were observed; some remain unidentified, but it was possible to single out acetate (OAc) and potassium (K) as key species displaying the largest variation in concentrations among the as-received PbI 2 . Acetate was identified as a detrimental impurity, while K impurities may be advantageous as suggested by the previous literature on alkali cation additives. A simple aqueous recrystallization successfully decreased the concentration of many impurities, and the results from devices fabricated from recrystallized PbI 2 reagents are interpreted in terms of their new impurity profiles. This work significantly contributes to the list of known impurities in perovskite reagents that researchers should be aware of, and we propose improved purification methods for perovskite precursors will further benefit device performance, run-to-run, and batch-to-batch reproducibility.

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“…Thus, it is crucial to remove all oxide impurities from precursors before crystal growth. In order to solve this problem, extensive efforts have been made to eliminate oxidic impurities by conventional physical filtration and chemical H 2 gas reduction. , However, the physical filtration method could introduce additional impurities, and the forming gas reduction method can only remove surface oxidation but not oxides present within the material.…”

Section: Introductionmentioning

confidence: 99%

Improved Crystal Growth of Tl₆SeI₄ for γ-Ray Detection Material by Oxide Impurity Removal

Lin

Kontsevoi

Liu

et al. 2017

Crystal Growth & Design

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Tl6SeI4 is a promising wide-bandgap semiconductor for room-temperature high-energy photon detection. Because of the air-sensitive Tl precursor or Tl-based binary precursors used in the synthesis, this material can contain deleterious Tl oxide impurities. These impurities lead to problems during syntheses and crystal growth including glass attack, tube rupture, and parasitic nucleation, which subsequently deteriorate detector performance. In this work, we present a facile way to chemically reduce Tl oxides and eliminate oxygen impurities in Tl6SeI4 by adding high-purity graphite powder during synthesis. The addition of carbon leads to reduction of the residual Tl oxides and formation of CO2 and CO. The resistivity and hard radiation detection performance for 122 keV γ-rays of Tl6SeI4 single crystals were significantly improved. The improvement in the crystallinity was also confirmed by a narrower near-band-edge emission band in the photoluminescence spectra. We confirmed that the reaction between Tl oxide and graphite occurs, and propose a mechanism which is highly effective in substantially reducing oxide impurities from Tl-containing precursors. First-principles density functional theory calculations reveal that the presence of interstitial oxygen atoms (Oint) leads to the formation of a deep level located near the middle of the gap, which can act as carrier traps detrimental to detector performance. The calculations also indicate that graphite addition is safe for detector performance because all carbon-induced defects have high formation energy and are not likely to appear in lattice.

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Removal of oxidic impurities for the growth of high purity lead iodide single crystals

Cited by 12 publications

References 30 publications

PbI₂–TiO₂ Bulk Heterojunctions with Long-Range Ordering for X-ray Detectors

PbI₂–TiO₂ Bulk Heterojunctions with Long-Range Ordering for X-ray Detectors

Analytical Evaluation of Lead Iodide Precursor Impurities Affecting Halide Perovskite Device Performance

Improved Crystal Growth of Tl₆SeI₄ for γ-Ray Detection Material by Oxide Impurity Removal

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Removal of oxidic impurities for the growth of high purity lead iodide single crystals

Cited by 12 publications

References 30 publications

PbI2–TiO2 Bulk Heterojunctions with Long-Range Ordering for X-ray Detectors

PbI2–TiO2 Bulk Heterojunctions with Long-Range Ordering for X-ray Detectors

Analytical Evaluation of Lead Iodide Precursor Impurities Affecting Halide Perovskite Device Performance

Improved Crystal Growth of Tl6SeI4 for γ-Ray Detection Material by Oxide Impurity Removal

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Product

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PbI₂–TiO₂ Bulk Heterojunctions with Long-Range Ordering for X-ray Detectors

PbI₂–TiO₂ Bulk Heterojunctions with Long-Range Ordering for X-ray Detectors

Improved Crystal Growth of Tl₆SeI₄ for γ-Ray Detection Material by Oxide Impurity Removal