Solution-Processed Organic Solar Cells with 9.8% Efficiency Based on a New Small Molecule Containing a 2D Fluorinated Benzodithiophene Central Unit
Solution-Processed Organic Solar Cells with 9.8% Efficiency Based on a New Small Molecule Containing a 2D Fluorinated Benzodithiophene Central Unit
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溶液处理%20有机%20太阳能%20细胞%20with%209.8%%20效率%20Based%20on%20a%20新%20小%20分子%20含%20a%202D%20氟化%20苯并二噻吩%20中央%20单位
DOI：
10.1002/aelm.201600061
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发表时间：
2016
影响因子：
6.2
通讯作者：
Peng Qiang
中科院分区：
文献类型：
--
作者：
Wang Zhenguo;Xu Xiaopeng;Li Zuojia;Feng Kui;Li Kai;Li Ying;Peng Qiang
DOI：10.1002/aelm。 201600061片段作为π共轭桥被提出来开发高效SM-OSC。[3e,f,4d,5b,8]这些分子表现出优异的成膜性、高载流子迁移率、宽而强的吸收，这归因于分子结构中的扩展共轭以及末端A单元和中心D基团之间的分子内电荷转移。显然，在这个有效的分子体系中，陈和同事们做了开创性和杰出的研究工作，其中他们还证明了中心构件对于增强光伏参数的重要性，例如开路电压（Voc）、短路电流密度（Jsc）、填充因子（FF）和整体器件性能。然后，一些芳香单元被纳入并广泛研究在这种类型的A-π-D-π-A主链作为中心嵌段，包括噻吩，[9]芴，[10]噻吩并[3, 2-b]-噻吩，[11]环戊基[2, 1-b; 3, 4-b']-二噻吩,[12] 二噻吩并-[3, 2-b: 2', 3'-d] 噻咯,[12] 二噻吩[3, 2-b; 6, 7-b] 咔唑，[13] 和苯并 [1, 2-b: 4, 5-b'] 二噻吩 (BDT)。 [14] 2011年，Chen及其同事用电子更丰富、平面性更好的BDT单元取代了中心噻吩单元，并报道了一种新的小分子（DCAO3T（BDT）3T），其PCE提高了5.48%。 [9]第二年，他们报道了一种包含中心烷氧基取代的 BDT 单元的类似分子（DR3TBDT），实现了 7.38% 的更高 PCE，优化后的 Voc 为 0.93 V，FF 为 65%。[14b] 为了进一步提高 Jsc 值，他们使用噻吩基修饰的 BDT（BDTT）作为中心单元，并报道了一种新的 2D 分子 (DR3TBDTT)，PCE 为 8.12%。[14c]当用溶剂蒸气退火方法 (SVA) 处理活性混合物以控制垂直偏析和域连接性时，基于 DR3TBDTT 的 SM-OSC 的 PCE 进一步提高至 9.58%。[15]最近，Li及其同事将烷硫基噻吩基侧链连接到BDT中心单元上，开发了一种新分子（BDTT-S-TR），该分子具有良好的晶体结构、广泛的吸收和高空穴迁移率，无需任何额外处理即可获得9.20%的PCE。 [16]这一巨大进展表明，只需对 BDT 中心结构单元进行微小改变，即可实现该分子系统光伏性能的显着提高。因此，仍然非常需要将仔细的分子设计和器件优化相结合来开发高效的 SM-OSC。 在本论文中，我们设计并制备了一种具有氟化 BDTT 中心嵌段和绕丹宁端基的新型分子供体材料，名为 DR3TBDTTF（方案 1），用于高性能 SM-OSC。还制备了DR3TBDTT的非氟化类似物用于进行比较。选择 BDTT 作为中心单元是因为它处理刚性、对称和平面的主干结构。与相比
DOI: 10.1002/aelm. 201600061 fragments as the π-conjugation bridges, was put forward to develop highly efficient SM-OSCs.[3e, f, 4d, 5b, 8] These molecules exhbited excellent film formation, high carrier mobility, wide and strong absorption, which were attributed to the extended conjugation in the molecular structure and intramolecule charge transfer between the terminal A units and the central D groups. Obviously, in this effective molecular system, Chen and co-workers did the pioneer and outstanding research work, in which they also demonstrated the importance of the central building block on the enhancement of photovoltaic parameters, such as the open-circuit voltage (Voc), shortcircuit current density (Jsc), fill factor (FF), and overall device performance. Some aromatic units were then incorporated and widely studied in this type of A-π-D-π-A backbone as the central block, including thiophene,[9] fluorene,[10] thieno [3, 2-b]-thiophene,[11] cyclopenta [2, 1-b; 3, 4-b′]-dithiophene,[12] dithieno-[3, 2-b: 2′, 3′-d] silole,[12] dithieno [3, 2-b; 6, 7-b] carbazole,[13] and benzo [1, 2-b: 4, 5-b′] dithiophene (BDT).[14] In 2011, Chen and co-workers replaced the central thiophene unit with a more electron-rich and better planar BDT unit, and reported a new small molecule (DCAO3T (BDT) 3T) with an improved PCE of 5.48%.[9] In the next year, they reported a similar molecule (DR3TBDT) containing a centrally alkoxy-substituted BDT unit, achieving a much higher PCE of 7.38% with an optimized Voc of 0.93 V and an FF of 65%.[14b] To further improve the Jsc value, they used thienyl-modified BDT (BDTT) as the central unit, and reported a new 2D molecule (DR3TBDTT) with a PCE of 8.12%.[14c] When the active blend was treated with a solvent vapor annealing method (SVA) to control the vertical segregation and domain connectivity, the PCE of DR3TBDTT-based SM-OSCs was further elevated to 9.58%.[15] Just recently, Li and co-workers attached the alkylthio-thienyl side chains on the BDT central unit, and developed a new molecule (BDTT-S-TR), which possessed good crystalline structure, broad absorption, and high hole mobility, giving rise to a PCE of 9.20% without any extra treatment.[16] The great progress indicates that significant improvement of photovoltaic property in this molecular system can be achieved with a minor change on the central BDT building block. Thus, it is still highly desirable to combine the careful molecular design and device optimization to develop the highly efficient SM-OSCs.In this contribution, a novel molecular donor material named as DR3TBDTTF (Scheme 1) with a fluorinated BDTT central block and rhodanine end groups was designed and prepared for high-performance SM-OSCs. Nonfluorinated analogue of DR3TBDTT was also prepared for making a comparison. BDTT is chosen as the central unit because it processes rigid, symmetric, and planar backbone structure. Compared with