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" İşlevselleştirilmiş perovskitlerin deneysel ve teorik olarak incelenmesi "
Özen, Sercan
Şahin, Hasan
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Latin Dissertation
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| Language of Document
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English
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| Record Number
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1059050
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| Doc. No
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TL58167
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| Main Entry
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Özen, Sercan
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| Title & Author
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İşlevselleştirilmiş perovskitlerin deneysel ve teorik olarak incelenmesi\ Özen, SercanŞahin, Hasan
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| College
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Izmir Institute of Technology (Turkey)
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| Date
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2020
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| Degree
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Master's
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| student score
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2020
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| Note
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87 p.
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| Abstract
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The last decade witnessed the rapid increase in the interest of the cesium lead halide perovskites (Cs-LHPs) and their successful applications in optoelectronic devices and photovoltaics. Increasing interest in perovskites arises from their extraordinary features such as having a tunable bandgap, variety in the crystal structure and phases, high photoluminescence quantum yield, ease of synthesis, and wide range absorption spectrum. Desiring to go beyond the emerging findings, subsequent studies have focused on the functionalization of perovskite nanocrystals (PNCs) by dimensional modifications and doping. This thesis study focuses on the modification of characteristics of Cs-LHPs by doping scenarios and dimensional reduction. Firstly, we reveal the modifications originated from the intercalation of Cr+3 and Gd+3 dopants into the Cs-LHP crystal structures. Cr+3 doping process is performed by using room temperature anti-solvent crystallization method. It is observed that the doping process leads to the emergence of distinctive signals in the PL spectrum. We clarify the origin of each additional PL peaks by experimental measurements and theoretical calculations. Additionally, white light emission is also achieved by the Cr3+ doping process. On the other hand, by using the hot-injection method, we synthesized neat and Gd+3 doped α-CsPbI3 NCs. The stability of α-CsPbI3 NCs is increased by the intercalation of Gd3+ ions into the host lattice. Also, enhancement of PLQY and lifetime is achieved by Gd3+ doping. Besides, to understand the dopant-induced modifications in the electronic and optical characteristics of perovskites, we also performed ab-initio density functional theory (DFT) calculations. In addition, we study how the characteristic properties of Cs-LHPs are modified upon dimensional reduction. By introducing the electrospraying method we reduced the synthesis and coating processes into a single step. Two-dimensional perovskite nanoplatelets were synthesized by electrospraying. We tuned the emission wavelengths of nanoplatelets in the range of 100 nm by thickness modifications. Lastly, by using DFT, we investigated the effect of thickness-dependent modifications on the structural, electronic, and vibrational properties of the orthorhombic CsPbI3 structure. Phonon calculations show that two ultra-thin forms of bulk CsPbI3 are dynamically stable. Also, the increase in the bandgap energy of the CsPbI3 structure by a decrease in thickness is revealed by electronic band dispersion calculations.
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| Descriptor
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Alternative energy sources
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Crystal lattices
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Crystal structure
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Efficiency
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Energy resources
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Engineering
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Ligands
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Nanocrystals
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Optical properties
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Phase transitions
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Renewable resources
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| Added Entry
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Şahin, Hasan
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| Added Entry
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Izmir Institute of Technology (Turkey)
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