有机-无机“桥接”型复合材料的构筑及其光电转换性能和机制研究

Due to the differences of physical properties and chemical bond between the organic and inorganic compounds, for organic-inorganic hybrid photovoltaic nanomaterials, there often exist the problem of organic/inorganic interface mismatch, which hinder the photogenerated charge carrier transmission, reducing photoelectric conversion efficiency..The project intends to use a functional sulfur-terminal transition metal complex M(S)2L to combine chalcogenide semiconductor nanocrystals together.In the M(S)2L complex, the two unsaturated coordinated sulfur atoms could endow M(S)2L significant function for as a "complex" ligand for the surface modification of inorganic nanomaterials. Particularly, for the M(S)2L complex, the terminal S atom and the center metal M could be expected as a "bridging" to connect various chalcogenide semiconductor nanocrystals and organic component L together at the molecular level, which would result in a novel organic-inorganic hybrid material with the "bridging" unit as the organic/inorganic interface at molecular level. Therefore, the "bridging" unit could significantly improve the organic/inorganic interface match..The study includes: (1) in situ preparation of chalcogenide semiconductor nanocrystals on the metal foil or conductive glass by solvothermal, electrochemical deposition,etc.(2) Bonding sulfur-terminal transition metal complex M(S)2L and chalcogenide semiconductor nanocrystals together by selecting the appropriate bonding conditions. (3) Studying on the photoelectric conversion characteristics and mechanisms of the novel organic/inorganic hybrid system based on a new interface structure model. .The implementation of this project could provide a new organic-inorganic interface structure model for the study of the photoelectric conversion mechanism of organic-inorganic hybrid materials, which would give rise to new ideas and technical support for in-depth understanding and revealing the nature of the interface separation, transportation, recombination of photogenerated charge carriers in photoelectric conversion process or other physical and chemical processes.

有机-无机复合光伏纳米材料因有机组分和无机组分在物理性质和化学键上的显著差异常常存在有机/无机界面严重失配问题，阻碍光生载流子的传输，降低光电转化效率。本项目拟用功能性双硫端基过渡金属配合物M(S)2L键合硫族半导体纳米晶，旨在以端基S原子和中心配位金属M做桥梁，"桥"接硫族半导体纳米晶和功能性有机分子L，在分子水平上构筑有机/无机桥接单元，从根本上解决界面失配问题。研究内容包括：（1）在金属基底或导电玻璃上通过溶剂热法、电化学沉积法等原位制备硫族半导体纳米晶薄膜；（2）选择合适的配位条件实现双硫端基配合物M(S)2L与硫族半导体纳米晶的配位键合；（3）建立界面结构模型，研究该类复合材料的光电转换特性和机制。本项目的开展将为有机-无机复合材料的光电转换机制研究提供新的界面结构模型，对于揭示光电转换过程的本质和深入理解光生载流子的界面分离、输运、复合等物理化学过程提供新思路和技术支撑。

有机-无机复合光伏纳米材料是一种以有机共轭化合物L作为电子给体、无机半导体纳米晶作为电子受体的新型异质结太阳能电池材料。有效解决有机/无机界面失配问题，并深度理解界面对光生载流子的分离和输运机制，提高光电转换效率是该领域最为重要的一个研究方向。基于此，本项目围绕“在分子水平上构筑ʻ桥接型ʼ有机-无机界面，探讨电荷载流子的界面分离和输运机制，改善复合材料的光电子特性”开展了一系列研究工作。首先，以D-π-A型三联吡啶衍生物L作为配位基，合成了Zn(S)2L和Cd(S)2L型双硫端基过渡金属配合物，研究了光电子特性。制备了一系列形貌和结构确定的金属硫化物纳米材料，包括： Cu2ZnSnS4纳米晶、S2掺杂的Cu7.2S4+x超晶格纳米线、Zn0.49Cu0.50S1.01超晶格纳米花、NaInS2纳米花、ZnS纳米晶、CdS纳米晶，ZnSn(OH)6立方体以及CuS和CdSe纳米晶薄膜等。然后，发展了纳米晶表面处理技术，获得了表面清洁的、金属离子裸露的硫化物纳米晶，成功地把双硫端基配合物通过其端基S原子键合在纳米晶表面，制备了ZnS/Zn(S)2L微球、CdS/Cd(S)2L微球、片状CuS/Cd(S)2L纳米薄膜和Cu7.2S6.20/Cd(S)2L纳米线等复合体，重点研究了ZnS/Zn(S)2L复合体的界面结构，建立了界面结构模型，并通过现代表征技术系统研究了该类复合材料界面处载流子的分离和输运特性和机制。研究发现，在该类“桥接型”复合材料中，配合物的配位金属中心和端基S原子能够作为π共轭的桥，使光生电子从有机组分L迁移到无机纳米晶，不仅引起有机分子π共轭体系的自去偶，而且大幅度地提升了复合体光生载流子的产出、分离和迁移效率。最后，初步探讨了该类复合材料在太阳能电池器件中的应用。本项目建立的界面结构模型为有机-无机复合材料的合成设计提供了科学借鉴意义，为深入理解光生载流子的界面分离、输运、复合等物理化学过程提供了主要科学依据。