| 摘要: | 利用電子豐盈與電子匱乏芳香環稠合而成之剛硬片段DTBZ (dithieno[3′,2′:3,4;2′′,3′′:5,6]benzo[1,2-d][1,2,3]triazole)作為雙極性非金屬系有機光敏染料之共軛架橋主體，引入不同的電子予體，如tripheneylamine (TPA)、9-(2-ethylhexyl)-9H-carbazole (CBZ)、4-(2-ethylhexyl)-4H-thieno[3,2-b]indole (TID)，以及不同的共軛架橋延伸片段，如thiophene (T)、3-n-hexyl-thiophene (HT)，並以2-cyanoacrylic acid作為電子受體兼錨基，本研究成功開發出新穎D-A′-A型光敏化染料 (YC系列染料)。本研究也對染料進行了光物理、電化學性質測量，以及製成染料敏化型太陽能電池進行測試，並搭配理論計算探討。
YC系列染料在362 nm到550 nm的光譜範圍有寬廣的吸收，且擁有不錯的消光係數，最高的消光係數達到~54800 M-1 cm-1。由於DTBZ的共面性，染料分子在TiO2上有相當程度的J-型堆疊，使得分子的吸收延伸至較長的波段。在標準AM 1.5光照度下，YC系列元件之光電轉換效率在5.82%到8.51%之間，最佳的YC-5 (8.51%)且超越標準品N719元件(8.12%)。從IPCE光譜可以很清楚看出J-型堆疊對於光電流的增益有很重要的貢獻，若加入5 mM的共吸附劑 (CDCA) 適度抑制堆疊導致的激態分子淬息，但保存長波段的光吸收，可將效率更提升至9.1%，且在1/4個標準太陽光照度下，其效率更可提升至10.56%。
;New D-A′-A type sensitizers (YC dyes), comprising different arylamine (tripheneylamine, 9-(2-ethylhexyl)-9H-carbazole or 4-(2-ethylhexyl)-4H-thieno[3,2-b]indole) as the electron donor, dithieno[3′,2′:3,4;2′′,3′′:5,6]benzo[1,2-d][1,2,3]triazole (DTBZ) with fused electron rich and electron deficient aromatic units as the rigidified π-conjugated spacer, and 2-cyanoacrylic acid as both the acceptor and anchor, have been synthesized and characterized. Thiophene or 3-n-hexyl-thiophene was also introduced to extend the conjugation. In addition to the investigation of the photophysical, electrochemical properties, theoretical computations were also carried out on these new dyes. Dye-sensitized solar cells were fabricated using these dyes as the senzitizers, and relevant physical measurements were conducted.
The YC sensitizers displayed broad absorption spectra covering the range of 362 to 550 nm, with the highest molar extinction coefficient up to ~54,800 M-1cm-1. Because of the planarity nature of DTBZ, the dyes have J-aggregation when adsorbed on the TiO2 surface, resulting extended absorption in the longer wavelength region. The light-to-electricity conversion efficiencies of the dye-sensitized solar cells (DSSCs) fabricated from the dyes range from 5.82 to 8.51% under simulated AM 1.5 G illumination, and the best cell efficiency (YC-5) surpasses that (8.12%) of the standard DSSC based on N719 ((bis(tetrabutyl-ammonium)-cis-di(thiocyanato)-N,N′-bis(4-
carboxylato-4′-carboxylic acid-2,2′-bipyridine)ruthenium(II)). The IPCE spectra clearly indicates that important contribution of J-aggregation of the dyes to the photocurrents. With addition of 5 mM of CDCA (chenodeoxycholic acid) as the coadsorbent to alleviate excited state quenching while retaining the gain at the longer wavelength region due to dye-aggregation, the best efficinecy was further boosted to 9.10%. Under 25% sunlight illumination, the efficiency reached 10.56%. |
