Određivanje optičkog procjepa tankog filma Taucovom metodom

undergraduate thesis

• Title (english): Determination of thin film bandgap by the use of Tauc's method
• Author: Nikolina Miočić
• Mentor: Jelena Macan (mentor)
• Committee member: Jelena Macan (predsjednik povjerenstva)
• Committee member: Anita Šalić (član povjerenstva)
• Committee member: Katarina Mužina (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2024-09-16, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Chemical Engineering

Abstract

Cilj ovog rada je određivanje optičkog procijepa za direktni i indirektni prijelaz elektrona tri uzorka tankih filmova lantanova manganita (LaMnO3) korištenjem Taucove, Codyjeve i Boltzmannove metode. Uzorci su pripremljeni različitim sintetskim postupcima što utječe na iznos optičkog procijepa. Morfološke karakteristike ispitane su pretražnom elektronskom mikroskopijom (SEM), te je vidljiva nehomogenost tankih filmova na sva tri uzorka što uvelike utječe na reflektanciju i transmitanciju. Optička svojstva analizirana su UV-Vis spektroskopijom u rasponu od 380 do 800 nm. Optički procijepi teško su odredivi za većinu uzoraka, te se nalaze u rasponu od 0,3 eV do 2,5 eV. Unatoč tome što se za određivanje optičkog procijepa najčešće koriste Taucova i Codyjeva metoda, pokazalo se da Boltzmannova metoda daje reprezentativnije rezultate jer uzima u obzir cijelu krivulju, a ne vizualno određeno linearno područje. Nijedna metoda nije uspjela sigurno odrediti dolazi li do direktnog ili indirektnog prijelaza elektrona, zbog čega je potrebno provesti dodatna istraživanja ili provesti matematička modeliranja. Odabir prikladne metode za karakterizaciju optičkih svojstava novih materijala u primjeni za fotonaponske ćelije od presudne je važnosti kako bi se dobili pouzdani rezultati.

Abstract (english)

The aim of this paper is to determine the band gap value for the direct and indirect electron transition of three samples of thin films of lanthanum manganite (LaMnO3) using Tauc, Cody and Boltzmann methods. The samples are prepared by different procedures which affects the band gap value. Morphological characteristics were examined by scanning electron microscopy (SEM), and the inhomogeneity of thin films on all three samples was visible, which greatly affects reflectance and transmittance. Optical properties were analyzed by
UV-Vis spectroscopy ranging from 380 to 800 nm. Band gap values, ranging from 0.3 eV to 2.5 eV, were difficult to determine for most samples. Although Tauc's and Cody's methods are most commonly used to determine the optical slit, Boltzmann's method has been shown to yield more representative results because it takes into account the entire curve rather than a visually defined linear region. Neither method has been able to determine for sure whether there is a direct or indirect electron transition, which requires additional research or mathematical modeling. It is important to choose the appropriate method for characterizing the optical properties of new materials in application for photovoltaic cells in order to get the most accurate results possible.

• Keywords: lantanov manganit; optički procijep; perovskitne solarne ćelije; tanki filmovi; Taucova metoda
• Keywords (english): lanthanum manganite; band gap; perovskite solar cells; thin films; Tauc method
• Language: croatian
• URN:NBN: urn:nbn:hr:149:665338
• Study programme: Title: Applied Chemistry - Undergraduate study; specializations in: Environmental chemistry and green technologies, Advanced materials and technologies, Applied organic chemistry; Course: Advanced materials and technologies; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) primijenjene kemije (sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) primijenjene kemije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2024-11-15 13:15:43