magistrsko delo
Ana Simčič Zuljan (Author), Tina Skalar (Mentor), Igor Plazl (Thesis defence commission member), Marjan Marinšek (Thesis defence commission member)

Abstract

Poraba električne energije od začetka industrijske revolucije vztrajno narašča. Ker so zaloge fosilnih goriv omejene, se raziskovalci usmerjajo v iskanje novih, alternativnih virov, predvsem obnovljivih. Glede na podatek, da lahko Sonce v enem dnevu proizvede več energije, kot jo človeštvo porabi v enem letu, je presenetljivo da ta vir energije ni pogosteje uporabljen. Razlog za to so previsoki stroški proizvodnje glede na nizke izkoristke pretvorbe električne energije, ki jo dosegajo silicijeve sončne celice. Zato strokovnjaki na fotovoltaičnem področju raziskujejo nadomestke silicijevih sončnih celic. Eden od bolj obetavnih alternativ so perovskitni materiali. Prvič so bili predlagani v fotovoltaične namene šele leta 2006, od takrat pa je njihova učinkovitost narasla od 2,2 % do 25,5 % v letu 2020. Absorpcijsko plast v perovskitni sončni celici sestavljajo 3D mešani organsko-anorganski perovskiti s splošno formulo ABX3. Najbolj raziskan in uporabljen je trenutno metilamonijev svinčev jodid, CH3NH3PbI3, vendar se zaradi strupene narave svinca raziskuje uporaba drugih kovin. Poleg kovine se lahko menja organski kation na A mestu ter halogenidni anion X. S spreminjanjem ionov se spreminja kristalna struktura, kar vpliva na električne in optične lastnosti materiala. Niso pa vsi perovskiti primerni za sončne celice. Parametra, ki določata ali bo nek perovskit uporaben v fotovoltaiki ali ne, sta tolerančni in oktaedrični faktor. V magistrski nalogi smo se osredotočili na sintezo in karakterizacijo mešanih organsko-anorganskih perovskitov, ki imajo na anionskem mestu jodidni ion. Po pregledu ustrezne literature ter izračunu tolerančnih in oktaedričnih faktorjev, s katerimi smo preverili, da pride do tvorbe idealne kubične strukture, je sledila sinteza petih različnih perovskitov. Sinteza je potekala v dveh delih, in sicer smo najprej pripravili organski del, v drugem delu pa smo tega raztopili skupaj z anorganskim jodidom v izbranem topilu. Štirje od pripravljenih perovskitov so imeli na A mestu metilamonijev jodid, za raztapljanje pa smo uporabili topilo GBL. Zadnji sintetiziran perovskit je imel na mestu A mešan kation, sestavljen iz formamidinijevega in cezijevega jodida, kot topilo pa smo uporabili mešanico DMF in DMSO. Pripravljene perovskite smo okarakterizirali s pomočjo rentgenske praškovne difrakcije, difrakcije monokristala ter optične mikroskopije. Tistim perovskitom, ki so bili uspešno sintetizirani, pa smo preverili še UV ter termično obstojnost. XRD analiza je pokazala, da smo uspešno sintetizirali oba organska prekurzorja, MAI ter FAI. Od perovskitov pa smo dobili željen produkt le pri sintezi MAPbI3. Pri kositrovem analogu se je v strukturo vrinil Br, pri Ca in Cd perovskitu pa smo imeli precej težav že s samo sintezo, zato smo jo morali nekako prilagoditi. Nov način sušenja je rezultiral v perovskitni strukturi MACdI3, medtem ko je pri Ca analogu nastala nova, še neraziskana spojina. Tej spojini smo s pomočjo difrakcije monokristala uspešno določili kristalno strukturo. Pri sintezi FA0,83Cs0,17PbI3 pa nismo dobili homogenega perovskita, temveč je produkt vseboval dve fazi.

Keywords

sončne celice;organo-kovinski materiali;sinteza;obstojnost;rentgenska praškovna difrakcija;XRD;magistrska dela;

Data

Language: Slovenian
Year of publishing:
Typology: 2.09 - Master's Thesis
Organization: UL FKKT - Faculty of Chemistry and Chemical Technology
Publisher: [A. Simčič Zuljan]
UDC: 620.1(043.2)
COBISS: 134282499 Link will open in a new window
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Other data

Secondary language: English
Secondary title: Synthesis and characterization of mixed organo-metallic perovskite materials
Secondary abstract: Electricity consumption has been steadily increasing since the beginning of the industrial revolution. Since fossil fuel reserves are limited, researchers are focusing on the search for new, alternative sources, especially renewable ones. Considering that the Sun can produce more energy in one day than humanity consumes in a year, it is surprising that this source of energy is not used more often. The reason for this is the cost of production, given the low efficiencies of electricity conversion achieved by silicon solar cells. Therefore, experts in the photovoltaic field are researching substitutes for silicon solar cells. One of the more promising alternatives are perovskite materials. They were first proposed for photovoltaic purposes only in 2006, and since then their efficiency has increased from 2.2 % to 25.5 % in 2020. The absorption layer in a perovskite solar cell consists of 3D mixed organic-inorganic perovskites with the general formula ABX3. The most studied and used currently is methylammonium lead iodide, CH3NH3PbI3, but due to the toxic nature of lead, the use of other metals is being explored. In addition to the metal, the organic cation in the A site and the halide anion X can be changed. By changing the ions, the crystal structure changes, which affects the electrical and optical properties of the material. However, not all perovskites are suitable for solar cells. The parameters that determine whether a perovskite will be suitable in photovoltaics or not are the tolerance factor and the octahedral factor. In the master thesis, we focused on the synthesis and characterization of mixed organic-inorganic perovskites, which have an iodide ion at the anionic site. After reviewing the relavant literature and calculating the tolerance and octahedral factors, which were used to verify that an ideal cubic structure would be formed, the synthesis of five different perovskites was done. The synthesis took place in two parts: first, we prepared the organic part, and in the second part, we dissolved it together with the inorganic iodide in the selected solvent. Four of the prepared perovskites had methylammonium iodide at the A site, and GBL solvent was used for dissolution. The last synthesized perovskite had a mixed cation consisting of formamidinium and cesium iodide at the A site, while DMF and DMSO were used as a solvent mixture. The prepared perovskites were characterized using X-ray powder diffraction, single crystal diffraction and optical microscopy. Those perovskites that were successfully synthesized were also tested for UV and thermal stability. XRD analysis showed that we successfully synthesized both organic precursors, MAI and FAI. From perovskites, the desired product was obtained only in the synthesis of MAPbI3. With the tin analogue, Br crept into the structure, and with the Ca and Cd perovskite, we had a lot of troubles with the synthesis itself, so we had to somehow adapt it. A new drying method resulted in the MACdI3 perovskite structure, while the Ca analogue resulted in a new, yet unexplored compound. The crystal structure of this compound was successfully determined using single crystal diffraction. In the synthesis of FA0.83Cs0.17PbI3, we did not obtain a homogeneous perovskite, but the product contained two phases.
Secondary keywords: perovskite;organo-metal;synthesis;XRD;stability;Perovskit;Univerzitetna in visokošolska dela;
Type (COBISS): Master's thesis/paper
Study programme: 1000376
Embargo end date (OpenAIRE): 1970-01-01
Thesis comment: Univ. v Ljubljani, Fak. za kemijo in kemijsko tehnologijo, smer Kemijsko inženirstvo
Pages: 81 str.
ID: 16800851