新型可水/醇溶液加工的液晶静电组装共轭小分子电解质调控聚合物太阳能电池阴极界面特性及其光伏性能

To improve polymer solar cells performance, novel water/alcohol soluble liquid crystal-assembled conjugated small molecular electrolyte is proposed to regulate cathode interfacial properties. By rational design of water/alcohol soluble conjugated small molecular electrolytes with one dimension long axis skeleton (including p-type and n-type) and ionized liquid crystals with opposite charge, novel water/alcohol solution processed, highly ordered liquid crystal/ conjugated small molecular nanocomposite will be developed for cathode electrolyte interfacial layer. In the novel liquid crystal/conjugated small molecular nanocomposite, the cooperative effect of orientation of the liquid crystals and electrostatic interaction between the negative/positive charges can induce ordered structural arrangement. More importantly, LC-assistant electrostatic assembly can further promote highly orientated dipole moment along with the induced built-in electric field, which will significantly reduce the work function of cathode and favor better energy alignment. Moreover, due to the electrolytes surrounded by the hydrophobic mesogens, the electrostatic complex not only can be easily coated onto the highly hydrophobic surface of the active layer, but also will improve the stability of interfacial layer. The cooperative effect of orientation of the liquid crystals and electrostatic interaction between the negative/positive charges on the interfacial morphology, the orientation of the dipole moment, energy barrier between the active layer and electrode, and the work function of cathode will be studied, and the working mechanism of the novel electrolytes interfacial layer will be give a special attention. Finally, high performance photovoltaic devices based on this highly ordered liquid crystal/ conjugated small molecule nanocomposite as cathode interlayer will be fabricated and optimized.

本项目提出利用水或醇溶性液晶静电组装共轭小分子电解质来调控聚合物太阳能电池阴极界面特性，提高器件效率。合理地设计可水或醇溶液加工的高纯度一维长轴型共轭小分子电解质（包括p型和n型），并向其中引入带有相反电荷的离子化液晶分子，利用阴阳离子静电组装和液晶取向诱导效应协同驱动电解质分子有序组装，同时诱导界面偶极矩沿内建电场方向高度有序取向，降低阴极功焓，减少活性层与电极之间的势垒，从而构筑可水或醇溶液加工的、高度有序的新型液晶/共轭小分子纳米复合电解质阴极界面层。另外，由于亲油性液晶基元包裹在共轭电解质外层，不但可以进一步提高界面层在活性层上的成膜性能，还能进一步提高其稳定性。深刻认识和理解液晶诱导取向和静电组装对界面微观形貌、偶极子极化方向和强度、电极与活性层材料之间的能量势垒及阴极界面功焓的调控机制。最后，直接利用其水或醇溶液加工电池阴极界面层，制备高性能聚合物太阳能电池。

本项目通过主链和侧链的合理选择，引入液晶等方式，设计了一系列P型和N型水/醇性共轭电解质分子,并应用于有机聚合物太阳能电池界面缓冲层。研究发现，利用液晶、铁电性等分子可以很好的诱导界面偶极取向，发现了三重偶极效应，降低了界面势垒，提高了电荷提取和收集效率；利用主链工程和自掺杂效应协同调控阴极界面势垒和电导率，实现了界面层对电荷的选择性提取和高效传输，解决了聚电解质界面缓冲层对厚度敏感性难题，提高界面层的普适性；提出了嵌段共轭聚电解质自组装诱导活性层face-on结构，引入预结晶层来诱导活性层结晶，通过简单的界面调控就实现活性层形貌的调控；利用共轭电解质原位修饰ZnO制备杂化异质结界面，降低界面缺陷，提高了界面相容性; 利用高迁移率碳材料协同分散PEDOT导电聚合物和优化分子构象，实现了卷对卷加工高电导率、高韧性和抗弯折性透明电极。深入研究了界面偶极子极化方向和强度、界面微观形貌对界面势垒及最终器件性能的影响，并在此基础上，通过溶液加工制备了高性能聚合物太阳能电池器件。