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X-ray structural analysis

Structure and Phase Transitions Study of New Semiconducting Organo-Mineral Perovskite

Speakers

  • Dr. Alexander SHMAKOV

Primary authors

Co-authors

Content

In a last few years a semiconducting material methylammonium lead triiodide CH3NH3PbI3 with perovskite-like structure which has got general name Organo-Mineral Perovskite (OMP) attracts growing interest of researchers. Based on OMP Thin Film Solar Cells for several years of development demonstrate outstanding growth of efficiency of solar light to electricity conversion (from 4 up to 22%) [1]. Such a great performance becomes possible due to unique properties of OMP – optimal for solar cell energy gap width (1.5 eV), high solar light absorption coefficient (105 cm-1), low exciton decay energy (16 meV), and large path length of charge carriers (1mcm in thin film and 175 mcm in single crystal). OMP may be applied as well for lasers, LEDs, X-ray and -ray detectors. We have developed synthesis method and synthesized OMP single crystals. To produce OMP powder two precursors were used: lead iodide and iodine methylamine. Single crystal growth was carried out from saturated solution with temperature decrease. Iodine hydride acid was used as a solvent. During the growth the temperature of solution was decreased under control from 65°C down to 21°C with step size of 0.1° for 40 min. The growth proceeded for 12 days. The chemical composition of single crystals was confirmed by means of energy dispersive spectroscopy (EDX) and photoelectron spectroscopy (XPS). Reflection High Energy Electron Diffraction (RHEED) indicates high quality of surface of single crystals synthesized. The crystal structure of CH3NH3PbI3 was investigated by means of synchrotron radiation XRD within wide temperature range allowing to detect phase transitions of OMP at ~160 and ~330 K

W.S. Yang, et al, Science, 356, 1376-1378, (2017)