Synthesis and characterizations of red/near-IR absorbing A-D-A-D-A-type oligothiophenes containing thienothiadiazole and thienopyrazine central units
Synthesis and characterizations of red/near-IR absorbing A-D-A-D-A-type oligothiophenes containing thienothiadiazole and thienopyrazine central units
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DOI：
10.1039/c2jm13285k
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发表时间：
2012-01-01
影响因子：
--
通讯作者：
Baeuerle, Peter
中科院分区：
文献类型：
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作者：
Steinberger, Simon;Mishra, Amaresh;Baeuerle, Peter
已开发了一系列作为红色/近红外吸收剂的p-共轭A-D-A-D-A型低聚噻吩（1-3），其包含杂环噻吩并[3，4-c][1，2，5]噻二唑（TTDA）或噻吩并[3，4-B]吡嗪（TP）作为核和二氰基乙烯基（DCV）或三氟乙酰基（TFA）作为末端受体基团。通过紫外-可见光谱、循环伏安和热分析对所得低聚物进行了表征。这些低聚物的低能吸收带在溶液中位于620-707 nm，在薄膜中位于695-830 nm。理论研究表明，插入的双环非经典噻吩的共轭骨架施加部分quinoidal字符得到的低聚物，从而降低了带隙。从电化学测量得到的HOMO-LUMO能量为1-3，被发现适合于在通过真空沉积制备的平面异质结太阳能电池中与作为受体的富勒烯-C-60组合用作供体材料。结合这些低带隙低聚物的此类器件在空气质量（AM）1.5G照明下表现出高达0.60的高FF值和高达1.3%的功率转换效率。外量子效率（EQE）光谱清楚地显示了低能量吸收对总光电流的贡献。
A series of p-conjugated A-D-A-D-A-type oligothiophenes (1-3) comprising heterocyclic thieno[3,4-c][1,2,5] thiadiazole (TTDA) or thieno[3,4-b] pyrazine (TP) as the core and dicyanovinyl (DCV) or trifluoroacetyl (TFA) as terminal acceptor groups have been developed as red/near-IR absorbers. The resulting oligomers were characterized by UV-Vis spectroscopy, cyclic voltammetry and thermal analysis. The low energy absorption band of these oligomers was located at 620-707 nm in solution and at 695-830 nm in thin films. Theoretical studies reveal that the insertion of the bicyclic nonclassical thiophenes to the conjugated backbone imposed partial quinoidal character to the resulting oligomers and thus reduced the band gap. HOMO-LUMO energies of 1-3 derived from electrochemical measurements were found to be suitable for the use as donor material in combination with fullerene-C-60 as acceptor in planar heterojunction solar cells prepared by vacuum deposition. Such devices incorporating these low band gap oligomers exhibited high FF values up to 0.60, and power conversion efficiencies of up to 1.3% under air mass (AM) 1.5G illumination. External quantum efficiency (EQE) spectra clearly showed the contribution of the low energy absorption to the overall photocurrent.