二维钙钛矿/碳纳米管体相异质结的构建及其在碳基太阳能电池中的光电特性研究

Among various perovskite solar cells (PSC), carbon-based PSC (C-PSC) without hole transport materials is the most promising one for commercial application, but the application of three-dimensional (3D) perovskite limits the device stability. Introducing large organic ions with high water resistance into 3D perovskite to generate two-dimensional (2D) perovskite could improve the stability of both materials and device. However, the confinement effect induced by the insulating organic layer would prohibit the separation of electron-hole pairs and the transport of carriers, which hence would suppress the efficiency of 2D C-PSCs. For this reason, the applicant proproses to solve the problem by introducing carbon nanotube network into 2D perovskite (that is, construction of bulk heterojunction) to build fast hole transport channel and enlarge transfer interface. The following issues will be addressed. (1) The effect of carbon nanotubles on the growth behavior, crystal structure and allignment of 2D perovskite would be studied to build a relationship of the category and property of carbon nanotubes with the crystal structure and allignment. (2) The influence of bulk heterojunction on the separation of electron-hole pairs and carrier transport would be investagated in order to get a promising heterojunction for improving hole injection and transport. (3) The difference in ions movement, charge accumulation and J-V hysteresis between bulk heterojunction and pure 2D perovskite would also be probed and discussed for the purpose to control and reduce J-V hysteresis. These researches will offer method strategy and theoretical knowledge to improve the efficiency of 2D C-PSCs.

在各种钙钛矿太阳能电池（PSCs）中，无空穴传输材料的碳基PSCs（C-PSCs）具有较好的应用前景，但三维（3D）钙钛矿的使用限制了器件稳定性。在3D钙钛矿中引入具有防水特性的大有机离子来形成二维（2D）钙钛矿是提高材料和器件稳定性的重要选择。然而，绝缘性有机离子层引起的限域作用将抑制2D钙钛矿中载流子的有效分离和传输，制约电池效率。为此，申请者提出在2D钙钛矿中引入碳纳米管网络（即构建体相异质结）来形成空穴快速传输通道并扩大空穴转移界面以解决上述问题。拟研究（1）碳纳米管引入对2D钙钛矿晶体的生长过程、结构和取向的影响，确定碳纳米管种类和特性与晶体结构和取向的关联性；（2）体相异质结对载流子分离和传输的作用，获得可增强空穴注入和传输的异质结；（3）体相异质结对离子迁移、电荷界面聚集和J-V磁滞的影响，控制并减小J-V磁滞。为制备高效率2D C-PSCs提供理论和技术指导。

钙钛矿太阳能电池（PSCs）因成本低和转换效率高而受到人们广泛关注，但稳定性差严重制约了其商业化应用。由于无空穴传输层的碳基PSCs（C-PSCs）采用了高稳定性的碳电极替换了有机空穴传输层和金属电极，使其稳定性明显高于传统PSCs。但C-PSCs中采用的三维（3D）钙钛矿限制了器件稳定性的进一步提升，在3D钙钛矿中引入具有防水特性的大有机离子来形成二维（2D）或准2D钙钛矿是提高材料和器件稳定性的重要选择。然而，绝缘性有机离子层引起的空间限域作用抑制了2D钙钛矿中载流子的有效分离和传输，制约了电池效率。为此，本项目提出在2D钙钛矿中引入碳纳米管网络（即构建体相异质结）来形成空穴快速传输通道并扩大空穴转移界面以解决上述问题。具体来说，项目研究了一系列大尺寸离子与PbI2前驱体组合用于溶液法沉积低维钙钛矿，发现了PZDI2可以与PbI2前驱体反应生长RP结构的2D钙钛矿，制备并研究了 PbI2-PZDI2 2D钙钛矿的结构和光电性质，获得了该2D钙钛矿的引入对于材料和器件性能的影响规律；研究了不同有机大尺寸离子对传统3D钙钛矿薄膜的表面处理，获得了表面处理对于表面结构、光电性质、能级结构、晶体缺陷等的影响规律和机制；发现了Py+离子可与3D钙钛矿原位反应生成Py2CsPb2I7准2D钙钛矿表面层，用于钝化晶体缺陷并提高了稳定性；利用不同Cs盐对于无机钙钛矿进行表面处理，研究了阴离子与I-离子之间尺寸和性质差异对离子分布的影响，揭示了阴离子偏聚行为的内在影响机制，其中CsCl处理不仅可以形成成分和能级梯度，而且形成了Cs2PbI2Cl2 2D电子阻抗层，有效加速电荷分离和器件性能；将不同功能化的碳纳米管用于碳电极的构建，研究了碳纳米管性质、沉积方法和工艺等对于电极形貌和物化性质的影响，获得了不同碳纳米管电极对器件性能的影响规律和机制，研究获得了温度对钙钛矿结构和光电特性的影响规律和作用机制，探究了整体器件在高温条件下的稳定性。因此，本项目的研究为制备高性能C-PSCs提供了新思路，促进了其商业化发展。