含1,4-取代萘與噻吩單元為共軛架橋之非金屬光敏染料太陽能電池
Abstract
本論文利用Stille coupling、Bucheald-Hartwig couping、Kumada coupling reaction、Knoevenagel condensation等反應為合成手段，合成出一系列非金屬系雙極性有機光敏染料(metal-free organic dyes)。這些染料的基本架構是以arylamine作為電子予體(donor)，cyanoacrylic acid為電子受體(acceptor)，並以萘基(naphthyl)與噻吩(thiophene)單元構成兩者間之共軛架橋(spacer)。隨著架橋之變化，這些化合物之HOMO與LUMO能階可以調變。利用光物理與電化學量測，以及TDDFT理論計算，我們得以得知這些化合物之物性與結構之關連性。一些分子有較寬與不對稱螢光光譜，顯示雙重發光(dual emission)特性，此也經excitation spectra證實。
以這些化合物為光敏染料組裝成之染料敏化太陽能電池(dye-sensitized solar cell, DSSC)具有中等光電轉換效率，介於3.03至4.38%之間。雖然naphthylene的quinoidal之結構有利於電荷轉移，但其與隔鄰的芳香環有較大的二面角，卻也抵消了此效應，我們也由理論計算印證此點。未來將引入烯或炔基於naphthylene與芳香環間，以期電荷轉移之最佳化。
A series of metal-free dipolar organic dyes have been synthesized by ultilizing Stille coupling, Buchwald-Hartwig couping, Kumada coupling, and Knoevenagel condensation reactions. These dyes consist of an arylamine as the electron donor, 2-cyanoacrylic acid as the electron acceptor, and a naphthylene- and/or thiophene-based conjugated spacer between the donor and the acceptor. Tuning of the HOMO and LUMO energy levels tuning is achieved by varying the spacer. Photophysical and electrochemical studies, and TDDFT calculations were carried out on these molecules to elucidate the correlation between the physical properties with the molecular structure. The broad and asymmetric emission spectra observed in some compounds indicate dual emission characteristic, which was confirmed by the excitation spectra. DSSCs (dye-sensitized solar cells) based on these sensitizers exhibit moderate energy conversion efficiencies, ranging from 3.03 to 4.38%. Though quinoidal resonance structure of naphthylene is beneficial to charge transfer, large dihedral angle between the naphthylene and the neighboring aromatic ring will counteract the effect, as evidenced by the computational results. Future modification of the dyes will be the incorporation of an alkene or alkyne entity between the naphthylene and the neighboring aromatic ring to optimize the charge transfer efficiency.
A series of metal-free dipolar organic dyes have been synthesized by ultilizing Stille coupling, Buchwald-Hartwig couping, Kumada coupling, and Knoevenagel condensation reactions. These dyes consist of an arylamine as the electron donor, 2-cyanoacrylic acid as the electron acceptor, and a naphthylene- and/or thiophene-based conjugated spacer between the donor and the acceptor. Tuning of the HOMO and LUMO energy levels tuning is achieved by varying the spacer. Photophysical and electrochemical studies, and TDDFT calculations were carried out on these molecules to elucidate the correlation between the physical properties with the molecular structure. The broad and asymmetric emission spectra observed in some compounds indicate dual emission characteristic, which was confirmed by the excitation spectra. DSSCs (dye-sensitized solar cells) based on these sensitizers exhibit moderate energy conversion efficiencies, ranging from 3.03 to 4.38%. Though quinoidal resonance structure of naphthylene is beneficial to charge transfer, large dihedral angle between the naphthylene and the neighboring aromatic ring will counteract the effect, as evidenced by the computational results. Future modification of the dyes will be the incorporation of an alkene or alkyne entity between the naphthylene and the neighboring aromatic ring to optimize the charge transfer efficiency.
Description
Keywords
非金屬光敏染料太陽能電池, 雙極性有機光敏染料, 萘, 噻吩, Metal-free sensitizers, dye-sensitized solar cells, naphthylene, thiophene