低維度手性鈣鈦礦暨高分子之光學特性研究與分析
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2022
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本文研究三種材料：近年來鈣鈦礦著重研究的結構－準二維(Quasi-two-dimensional)下的Ruddlesden-Popper Perovskite(RPP)結構鈣鈦礦、日前逐漸引起關注的手性鈣鈦礦(chiral perovskites)，以及有機高分子材料。在準二維下的RP鈣鈦礦的研究中，本文選擇有機鹵化鈣鈦礦PEA2(FABr3)2PbBr4做研究，透過旋塗製程、熱退火製程形成鈣鈦礦薄膜並且使用蒸鍍製程實現發光二極體元件，其中以Quinhydrone(QH)的溶液來對鈣鈦礦薄膜進行表面鈍化的處理，並針對研究結果做討論。在手性鈣鈦礦的研究中本文透過旋塗製程、熱退火製程做出低維度(S-/R-MBA)2(Cs0.8MA0.2)n – 1PbnBr3n + 1的薄膜，並著重在<n>= 2化學劑量下的基礎改變手性配體 S-/R-MBABr的比例。研究結果顯示可以透過一般化學劑量製作出純相<n>= 1的薄膜，然 <n>= 2結構則為 <n>= 1以及<n>= ∞ 組成，並未出現預期的純相<n>= 2結構，因此分析其原因；並且在不依靠公認的化學劑量配方調配手性配體後，可以將圓二色光譜的gabs值可以高達~0.01(10-2等級)，可供日後製程研究上的參考。
有機高分子材料的研究中本文選用PTB7-Th (Poly{4,8-bis[5-(2-ethylhexyl)thiophen-2-yl]benzo[1,2-b:4,5-b']-dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)carbonyl]-thieno[3,4-b]thiophene-4,6-diyl}),PM6(PBDB-T-2F)( Poly[(2,6-(4,8-bis(5-(2-ethylhexyl-3-fluoro)thiophen-2-yl)-benzo[1,2-b:4,5-b’]dithiophene))-alt-(5,5-(1’,3’-di-2-thienyl-5’,7’-bis(2-ethylhexyl)benzo[1’,2’-c:4’,5’-c’]dithiophene-4,8-dione)]),PM7(PBDB-T-2Cl)(Poly[(2,6-(4,8-bis(5-(2-ethylhexyl-3-chloro)thiophen-2-yl)-benzo[1,2-b:4,5-b’]dithiophene))-alt-(5,5-(1’,3’-di-2-thienyl-5’,7’-bis(2-ethylhexyl)benzo[1’,2’-c:4’,5’-c’]dithiophene-4,8-dione)])的溶液作為研究對象，透過改變溶液溫度以及濃度進行光譜的量測探討其於H/J聚集型態下的激子離域現象，研究結果顯示透過調整溫度與濃度可獲得H/J聚集型態改變，並且也獲得了PTB7-Th, PM6, PM7的濃度分別為0.116 mg/ml, 0.115 mg/ml, 0.05 mg/ml時具有230 meV,184 meV,160 meV的戴維多夫分裂(davydov splitting)。
There are three works in this thesis: Quasi-two-dimensional structure with Ruddlesden-Popper Perovskites,low-dimensional chiral perovskites,and conjugated polymer materials.PEA2(FABr3)2PbBr4 took the role of quasi-two-dimensional structure and was used in this work for fabrication of Perovskite Light-Emitting Diode (PeLED) .In order to improve the external quantum efficiency, the solution of Quinhydrone (QH) is used for surface passivation.However the external quantum efficiency results did not improve after the modification of the Quinhydrone solution, so discussion and analysis were mention in the end of this work.In this work, R- and S-methylbenzylammonium bromide (R-MBABr and S-MBABr) was use as chiral ligand and using stoichiometric solutions with ⟨n⟩ = 1 and ⟨n⟩ = 2. The chiral perovskite film prepared from the precursor solutions with ⟨n⟩ = 1 is composed of (S-/R-MBABr)2PbBr4, whereas the films which were prepared from the precursor solutions with ⟨n⟩= 2 are a mixture of (S-/R-MBA)2(Cs0.8MA0.2)n – 1PbnBr3n + 1 with n = 1 and large n values.Also breaking the rule of stoichiometric to focus on ⟨n⟩ = 2 by changing chiral ligand .This way was committed to find the pure structure of ⟨n⟩ = 2.However the film prepared from changing chiral ligand did not reach our expectation.Instead creating a huge Circular dichroism(CD) signal up to 367 medg,and gabs can reach to 0.004 (~10-3).The conjugate polymer material PTB7-Th (Poly{4,8-bis[5-(2-ethylhexyl)thiophen-2-yl]benzo[1,2-b:4,5-b']-dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)carbonyl]-thieno[3,4-b]thiophene-4,6-diyl}),PM6(PBDB-T-2F)( Poly[(2,6-(4,8-bis(5-(2-ethylhexyl-3-fluoro)thiophen-2-yl)-benzo[1,2-b:4,5-b’]dithiophene))-alt-(5,5-(1’,3’-di-2-thienyl-5’,7’-bis(2-ethylhexyl)benzo[1’,2’-c:4’,5’-c’]dithiophene-4,8-dione)]),and PM7(PBDB-T-2Cl)(Poly[(2,6-(4,8-bis(5-(2-ethylhexyl-3-chloro)thiophen-2-yl)-benzo[1,2-b:4,5-b’]dithiophene))-alt-(5,5-(1’,3’-di-2-thienyl-5’,7’-bis(2-ethylhexyl)benzo[1’,2’-c:4’,5’-c’]dithiophene-4,8-dione)] )was prepared for solution. Photoluminescence(PL), Photoluminescence Excitation (PLE) and Absorption at room or high temperature were performed and analyzed. Exciton delocalization over aggregates were been studied in this work.By increasing the solution of concentration of PTB7-Th/PM6/PM7, the Davydov splitting are 230 meV,184 meV,160 meV respectively.
There are three works in this thesis: Quasi-two-dimensional structure with Ruddlesden-Popper Perovskites,low-dimensional chiral perovskites,and conjugated polymer materials.PEA2(FABr3)2PbBr4 took the role of quasi-two-dimensional structure and was used in this work for fabrication of Perovskite Light-Emitting Diode (PeLED) .In order to improve the external quantum efficiency, the solution of Quinhydrone (QH) is used for surface passivation.However the external quantum efficiency results did not improve after the modification of the Quinhydrone solution, so discussion and analysis were mention in the end of this work.In this work, R- and S-methylbenzylammonium bromide (R-MBABr and S-MBABr) was use as chiral ligand and using stoichiometric solutions with ⟨n⟩ = 1 and ⟨n⟩ = 2. The chiral perovskite film prepared from the precursor solutions with ⟨n⟩ = 1 is composed of (S-/R-MBABr)2PbBr4, whereas the films which were prepared from the precursor solutions with ⟨n⟩= 2 are a mixture of (S-/R-MBA)2(Cs0.8MA0.2)n – 1PbnBr3n + 1 with n = 1 and large n values.Also breaking the rule of stoichiometric to focus on ⟨n⟩ = 2 by changing chiral ligand .This way was committed to find the pure structure of ⟨n⟩ = 2.However the film prepared from changing chiral ligand did not reach our expectation.Instead creating a huge Circular dichroism(CD) signal up to 367 medg,and gabs can reach to 0.004 (~10-3).The conjugate polymer material PTB7-Th (Poly{4,8-bis[5-(2-ethylhexyl)thiophen-2-yl]benzo[1,2-b:4,5-b']-dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)carbonyl]-thieno[3,4-b]thiophene-4,6-diyl}),PM6(PBDB-T-2F)( Poly[(2,6-(4,8-bis(5-(2-ethylhexyl-3-fluoro)thiophen-2-yl)-benzo[1,2-b:4,5-b’]dithiophene))-alt-(5,5-(1’,3’-di-2-thienyl-5’,7’-bis(2-ethylhexyl)benzo[1’,2’-c:4’,5’-c’]dithiophene-4,8-dione)]),and PM7(PBDB-T-2Cl)(Poly[(2,6-(4,8-bis(5-(2-ethylhexyl-3-chloro)thiophen-2-yl)-benzo[1,2-b:4,5-b’]dithiophene))-alt-(5,5-(1’,3’-di-2-thienyl-5’,7’-bis(2-ethylhexyl)benzo[1’,2’-c:4’,5’-c’]dithiophene-4,8-dione)] )was prepared for solution. Photoluminescence(PL), Photoluminescence Excitation (PLE) and Absorption at room or high temperature were performed and analyzed. Exciton delocalization over aggregates were been studied in this work.By increasing the solution of concentration of PTB7-Th/PM6/PM7, the Davydov splitting are 230 meV,184 meV,160 meV respectively.
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Keywords
鈣鈦礦, 手性鈣鈦礦, 共軛有機高分子, Perovskite, Chiral perovskite, Conjugate polymer