Dr. Lioz ETGAR

Dr. Lioz ETGAR

The Institute of Chemistry, The Hebrew University of Jerusalem, Israel

Two Dimensional organic-inorganic perovskite from nanostructures to solar cells

Perovskite is a promising light harvester for use in photovoltaic solar cells. In recent years, the power conversion efficiency of perovskite solar cells has been dramatically increased, making them a competitive source of renewable energy. This work will discusses new directions related to organic inorganic perovskite and their applications in solar cells.

In low dimensional systems, stability of excitons in quantum wells is greatly enhanced due to the confined effect and the coulomb interaction. The exciton binding energy of the typical 2D organic-inorganic perovskites is up to 300 meV and their self-assembled films exhibit bright photoluminescence at room temperature.

  • In this work we will show the dimensionality in the perovskite structure. The 2D perovskite structure should provide stable perovskite structure compare to the 3D structure. The additional long organic cation, which is added to the perovskite structure (in the 2D structure), is expected to provide hydrophobicity, which will enhance the resistivity of the perovskite to humidity. Moreover we will demonstrate the use of 2D perovskite in high efficiency solar cells.
     
  • Organometal halide perovskite is used mainly in its “bulk” form in the solar cell. Confined perovskite nanostructures could be a promising candidate for efficient optoelectronic devices, taking advantage of the superior bulk properties of organo-metal halide perovskite, as well as the nanoscale properties. In this work, we present facile low temperature synthesis of two-dimensional (2D) lead halide perovskite nanorods (NRs). These NRs show a shift to higher energies in the absorbance and in the photoluminescence compared to the bulk material, which supports their 2D structure. X-ray diffraction (XRD) analysis of the NRs, demonstrates their 2D nature combined with the tetragonal 3D perovskite structure. In addition, by alternating the halide composition, we were able to tune the optical properties of the NRs. Fast Fourier Transform, and electron diffraction show the tetragonal structure of these NRs. By varying the ligands ratio (e.g. octylammonium to oleic acid) in the synthesis, we were able to provide the formation mechanism of these novel 2D perovskite NRs. 2D perovskite NRs are promising candidates for a variety of optoelectronic applications, such as light emitting diodes, lasing, solar cells and sensors. 

Biography

Lioz Etgar obtained his Ph.D. (2009) at the Technion–Israel Institute of Technology and completed post-doctoral research with Prof. Michael Grätzel (2009–2012) at EPFL, Switzerland. During his post-doctoral research, he received a Marie Curie Fellowship and won the Wolf Prize for young scientists. Since 2012, he has been a senior lecturer in the Institute of Chemistry at the Hebrew University. Etgar’s research group focuses on the development of innovative solar cells. Dr. Etgar is researching new excitonic solar cells structures/architectures while designing and controlling the inorganic sensitizer structure and properties to improve the PV parameters. Dr. Etgar published a pioneer work in the emerging field of perovskite-based solar cells; he was the first to demonstrate the possibility to work without hole conductor in perovskite based solar cells. Recently Dr. Etgar was awarded the prestigious Krill prize.