| 1. |
- Campanari, Valerio, et al.
(author)
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Reevaluation of Photoluminescence Intensity as an Indicator of Efficiency in Perovskite Solar Cells
- 2022
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In: Solar RRL. - : John Wiley & Sons. - 2367-198X. ; 6:8
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Journal article (peer-reviewed)abstract
- The photoluminescence (PL) intensity is often used as an indicator of the performance of perovskite solar cells and indeed the PL technique is often used for the characterization of these devices and their constituent materials. Herein, a systematic approach is presented to the comparison of the conversion efficiency and the PL intensity of a cell in both open-circuit (OC) and short-circuit (SC) conditions and its application to multiple heterogeneous devices. It is shown that the quenching of the PL observed in SC conditions is a good parameter to assess the device efficiency. The authors explain the dependence of the PL quenching ratio between OC and SC on the cell efficiency with a simple model that is also able to estimate the carrier extraction time of a device.
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| 2. |
- Salvato, Matteo, et al.
(author)
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Stoichiometric Bi(2)Se(3)topological insulator ultra-thin films obtained through a new fabrication process for optoelectronic applications
- 2020
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In: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3372 .- 2040-3364. ; 12:23, s. 12405-12415
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Journal article (peer-reviewed)abstract
- A new fabrication process is developed for growing Bi(2)Se(3)topological insulators in the form of nanowires/nanobelts and ultra-thin films. It consists of two consecutive procedures: first Bi(2)Se(3)nanowires/nanobelts are deposited by standard catalyst free vapour-solid deposition on different substrates positioned inside a quartz tube. Then, the Bi2Se3, stuck on the inner surface of the quartz tube, is re-evaporated and deposited in the form of ultra-thin films on new substrates at a temperature below 100 degrees C, which is of relevance for flexible electronic applications. The method is new, quick, very inexpensive, easy to control and allows obtaining films with different thickness down to one quintuple layer (QL) during the same procedure. The composition and the crystal structure of both the nanowires/nanobelts and the thin films are analysed by different optical, electronic and structural techniques. For the films, scanning tunnelling spectroscopy shows that the Fermi level is positioned in the middle of the energy bandgap as a consequence of the achieved correct stoichiometry. Ultra-thin films, with thickness in the range 1-10 QLs deposited on n-doped Si substrates, show good rectifying properties suitable for their use as photodetectors in the ultra violet-visible-near infrared wavelength range.
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| 3. |
- Wasowicz, Tomasz J., et al.
(author)
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Vacuum ultraviolet photoionization and ionic fragmentation of the isoxazole molecules
- 2020
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In: International Journal of Mass Spectrometry. - : Elsevier BV. - 1387-3806. ; 449
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Journal article (peer-reviewed)abstract
- The photofragmentation of the isoxazole molecules producing ionized atomic and molecular fragments was investigated in the photon energy range of 9–32 eV, using synchrotron radiation excitation combined with ion time-of-flight spectrometry. Twenty-one well resolved cations were identified in the mass spectra of the isoxazole, and their appearance energies were determined. The yield curves of these cations were obtained in the photon energy ranges from their appearance energies up to 32 eV. Moreover, the total ion yield of isoxazole was recorded with high precision in the photon energy range of 9.9–10.5 eV. This allowed the determination of the adiabatic ionization energy of 9.96 (0.02) eV in excellent agreement with earlier spectroscopic studies. Our results show that the dissociative ionization of isoxazole starts from the ring-opening and isomerization of isoxazole, and further it follows strictly through its ionic states. Possible ionic fragmentation channels yielding particular ions are discussed.
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