Simple and Versatile Molecular Donors for Organic Photovoltaics Prepared by Metal-Free Synthesis
Simple and Versatile Molecular Donors for Organic Photovoltaics Prepared by Metal-Free Synthesis
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DOI：
10.1002/chem.201405425
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发表时间：
2015-01-19
影响因子：
4.3
通讯作者：
Roncali, Jean
中科院分区：
文献类型：
--
作者：
Diac, Andreea;Demeter, Dora;Roncali, Jean
通过各种基于噻吩的π -共轭间隔基（1 - 5）将二苯腙单元连接到二氰基乙烯基受体基团而构建的给体 - 受体分子（D - π - A）由单醛或二醛通过一种简单的无金属方法合成。循环伏安法和紫外 - 可见吸收光谱表明，间隔基给体强度的延伸和/或增加会导致最高占据分子轨道（HOMO）和最低未占据分子轨道（LUMO）能级降低、吸收光谱红移以及分子吸收系数增加。与溶液相比，化合物1 - 3旋涂薄膜的光谱显示吸收带变宽且红移，这与J - 聚集体的形成一致。相反，含3,4 - 乙撑二氧噻吩（EDOT）的化合物4和5观察到的蓝移表明存在H - 聚集体。在以富勒烯C - 60为受体的太阳能电池中对给体1 - 5的溶液浇铸和真空沉积薄膜进行了评估。化合物2在基本结构的双层器件中获得了已报道的较高的功率转换效率。另一方面，用4和5得到的结果表明，结构中存在EDOT会对给体材料的组织和性能产生有害影响。
Donor-acceptor molecules (D-pi-A) built by connecting a diphenylhydrazone block to a dicyanovinyl acceptor group via various thiophene-based pi-conjugating spacers (1-5) were synthesized from mono- or dialdehydes by a simple metal-free procedure. Cyclic voltammetry and UV/Vis absorption spectroscopy show that the extension and/or increase of the donor strength of the spacer produces a decrease of the HOMO and LUMO energy level, a red shift of the absorption spectrum and an increase of the molecular absorption coefficient. Compared to solutions, the optical spectra of spin-cast thin films of compounds 1-3 show a broadening and red shift of the absorption bands, consistent with the formation of J-aggregates. In contrast the blue shift observed for the EDOT-containing compounds 4 and 5 suggests the presence of H-aggregates. Solution-cast and vacuum-deposited films of donors 1-5 were evaluated in solar cells with fullerene C-60 as acceptor. A power-conversion efficiency among the highest reported for bilayer devices of basic configuration was obtained with compound 2. On the other hand, the results obtained with 4 and 5 suggest that the presence of EDOT in the structure can have deleterious effects on the organization and performances of the donor material.