新型噻吩稠杂环π-桥有机光敏染料的构筑及性能研究

Dye-sensitized solar cells (DSSCs) based on metal-free organic sensitizers in conjunction with cobalt-electrolyte have received significant attention due to their remarkable photovoltaic performance. Nevertheless, the relatively narrow absorption bands and severe charge recombination in the TiO2/dye/electrolyte interface represent a major bottleneck for further improving photoelectric conversion efficiency. Extension of the conjugation length of the π-bridges is a straightforward method to enhance light-harvesting capability. However, this strategy may bring forth the inefficient conjugated degree due to the steric hindrance of adjacent conjugated units, thus impede the bathochromic effect. Based on these considerations, a series of novel broad spectral organic sensitizers incorporating N/Si-bridged thiophene fused heterocycle as the conjugated linker will be designed and synthesized. The excellent rigidification and coplanarity of π-bridge is beneficial to enhancing the light harvesting. In addition, it can efficiently suppress the charge recombination and improve charge migration efficiency by conveniently incorporating long alkyl chain or bulky substituent to the N/Si-position of π-linker. Furthermore, the absorption, electrochemical and photovoltaic properties for all these sensitizers will be systematically investigated to enucleate the fundamental structure-property relationship, and clarify the synergistic reaction between sensitizers and cobalt-electrolyte. Moreover, the physical properties of organic dyes based on cobalt-electrolyte will be obtained as well. This project will provide academic foundation and new insight into developing broad absorption, high-efficiency and highly stable organic sensitizers for dye-sensitized solar cells employing cobalt-electrolyte.

基于钴基电解质体系有机染料敏化太阳能电池（DSSCs）是当前太阳能光伏应用领域的研究热点。拓宽有机染料光谱响应范围和提高电子界面传输效率是进一步增强电池光电性能的核心关键。单纯延长共轭桥易因空间位阻造成平面扭曲，降低有效共轭程度，限制染料光谱红移。本项目拟设计合成系列含N/Si多元噻吩稠杂环新型共轭桥，基于分子工程构筑系列宽光谱吸收有机光敏染料。共轭桥刚性、共平面化能够更大程度拓宽红移吸收光谱，增强染料光捕获性能；同时利用N/Si取代基高修饰性，引入长烷基链或空间位阻基团，防止染料聚集和抑制电子复合，提高电子界面传输效率。本项目将系统研究染料的光学、电化学及光伏性能，阐明染料基础构效关系，揭示染料与电解质的协同作用规律，探索出适用钴基电解质体系有机光敏染料的物性特征。项目实施将丰富和完善钴基电解质DSSCs领域的相关理论，为研发高效、稳定的有机光敏染料提供新思路。

基于钴基电解质体系有机染料敏化太阳能电池是当前太阳能光伏应用领域的研究热点。拓宽有机染料光谱响应范围和提高电子界面传输效率是进一步增强电池光电性能的核心关键。单纯延长共轭桥易因空间位阻造成分子平面扭曲，降低有效共轭程度，限制染料光谱红移。针对上述科学难题，本研究通过新型π-共轭桥单元的设计优化，基于分子工程成功构建出20种含N/Si噻吩稠杂环桥连系列有机光敏染料。系统研究了该类染料的光学、电化学及光伏性能，探索了染料与电解质的协同作用及构效关系规律，揭示界面电子传输过程的高效机制。研究结果表明，共轭桥单元高度共轭、稠环化能够有效红移染料吸收光谱，增强染料的摩尔消光系数，有利于该类染料在基于钴基电解质体系中应用。同时，分子构型的刚性、共平面化还有助于提升染料的光热稳定性，延长电池器件的使用寿命。我们还提出了烷基侧边链的设计理念，在噻吩稠杂环共轭桥中引入侧边烷基链，在不显著降低染料光捕获性能的前提下，促使染料形成三维立体空间构型，具备更加优异的防自身聚集和抑制界面电子复合性能。此外，通过N/Si取代基和电子给体单元的调节，及大空间位阻基团相对位置调控，进一步优化了染料分子空间构型和电子轨道能级匹配，提升界面电子传输和分离效率。在标准测试条件下，该系列染料敏化太阳能电池获得了最高9.43%的光电转化效率。在此基础上，我们进一步将噻吩稠杂环拓展应用到钙钛矿太阳能电池中，开发了4种新型空穴传输材料，获得了高达20.49%的光电转化效率，且制备成本都显著低于商品化的Spiro-OMeTAD。本项目的实施为新一代太阳能光伏科技提供了重要的实验依据和理论参考，促进其产业化应用。