石墨相氮化碳/量子点异质结的可控制备及其光伏性能研究

Polymer/inorganic semiconducting quantum dots take advantage of the rich optoelectronic properties of polymers as well as the size and shape dependent band gaps of quantum dots semiconducting nanomaterials. As a result, polymer/inorganic semiconducting quantum dots exhibit high carrier mobilities as well as an increase in the range of light absorption. Here,we design and controllable synthesize the heterojunction of graphitic carbon nitride / Quantum dots and study theirs the photovoltaic performance as active layer.Polymeric carbon nitride is a typical semiconductor with a band gap of 2.7 eV, as revealed by theoretical calculations. Properties such as a low price, amenability to mass preparation and chemical modification, and especially, contrary to many other organic semiconductors, a high thermal and chemical stability against oxidation stable in air up to 550 o C, make carbon nitride solids a very promising candidate for solar energy converting systems, such as photoelectrochemical cells, which are not yet available. The processing condition of forming heterojunction was optimized and its reaction mechanism was also studied. The photovoltaic performance of solar cell is strongly dependent on the light harvesting, energy levels of materials, the morphology of heterojunction films, the g- C3N4 structure, the size of QDs, and so on. The impact of the above factors such as device structure, morphology of heterojunction on photovoltaic performance is discussing. Thus, the heterojunctions solar cells which have a lower cost and high efficiency should be obtained.

共轭聚合物/量子点太阳能电池兼具聚合物柔性、重量轻的特点和量子点带隙可调、多激子效应的特点而具有巨大的发展潜力，成为研究热点。本项目拟设计和制备能级匹配的石墨相氮化碳共轭聚合物/量子点异质结太阳能电池材料，并研究其光伏特性。石墨相氮化碳具有半导体结构，价格低廉，易进行化学修饰，化学与热稳定性高等特性，采用石墨相氮化碳作为聚合物电池新型受体，与无机半导体量子点直接键合形成异质结，既可使量子点不团聚，又可以促进光生电子-空穴的分离，减少他们的复合，从而有效提高光电转换效率，同时可以克服量子点电池的不稳定性。本项目将系统研究制备方法、条件对异质结结构的影响，探讨异质结形成机理，实现g-C3N4/量子点异质结微结构的可控制备。研究太阳能电池光电子的产生、分离、传输以及光电转换机理，揭示异质结电池的光伏特性与微结构的关系，建立相应的光电导模型。为潜在的高效低廉光伏电池的应用开发提供理论和实验基础。

共轭聚合物/量子点太阳能电池兼具聚合物柔性、重量轻的特点和量子点带隙可调、多激 子效应的特点而具有巨大的发展潜力，成为研究热点。本项目通过使用不同的方法合成g-C3N4/CdS复合材料及制备g-C3N4/C/CdS的石墨相氮化碳基三元复合材料，旨在提高石墨相氮化碳的光催化及光电性能。主要包括：. 采用一种新型、简单的原位法制备g-C3N4/CdS异质结，先使用软化学的方法在氮化碳中引入金属镉离子制备成Cd/g-C3N4，再将镉离子硫化，形成具有两种半导体掺杂的复合材料的异质结，研究发现制备得到的样品比纯的g-C3N4的光催化降解甲基橙高出2.5倍，光电流响应值高出2.3倍，光解水制氢高出2.8倍。说明原位法合成的复合物的催化活性比纯的g-C3N4高。. 采用超声和离子辅助的协同效应来获得的CdS/g-C3N4纳米复合材料的异质结。研究发现：CdS/g-C3N4纳米复合材料相比于纯的氮化碳表现出显著的光电流的增强。超声制备的CdS/g-C3N4复合材料相比于未经过超声制备的CdS/g-C3N4复合材料、纯的g-C3N4的光降解甲基橙，光电流响应值分别高出1.4倍，18倍和2倍，2.3倍。这说明复合材料的异质结有助于光生载流子的有效转移和分离，提高光催化和光电性能。. 我们创新的制备三元复合物g-C3N4/C/CdS，并考察其光催化和光电性能。研究结果表明，CdS/g-C3N4/C三元复合物的光催化降解甲基橙和光电流响应值分别比g-C3N4/C高出10倍和1.4倍，比g-C3N4高出12倍和2倍。实验证明，三种物质之间形成能带结构，从而更有利于载流子的分离和转移，进而更好的提高光催化、光电性能。. 本项目系统研究了制备方法、条件对异质结结构的影响，探讨异质结形成机理，实g-C3N4/量子点异质结微结构的可控制备。研究了光电转换机理，揭示异质结电池的光伏特性与微结构的关系。为潜在的高效低廉光伏电池的应用开发提供理论和实验基础。