新型两性共轭小分子改性的钙钛矿吸光材料及其在可印刷钙钛矿太阳能电池中的应用

Devices that convert sunlight into electricity are called photovoltaic solar cells. In recent years, perovskite solar cells have emerged as low-cost, high-efficiency solar cells, which has revolutionized the solar cell research field. However, the cells still suffer from problems like long-term durability and high cost, limiting their large-scale application. With experience in making monolithic solid-state mesoscopic solar cells, we firstly developed a fully printable mesoscopic PSC with the architecture of FTO/compact-TiO2/(mp-TiO2/mp-ZrO2/mp-carbon) /perovskite, (mp = mesoporous) aiming at reducing the material cost and simplifying the device fabrication process. Subsequently, various approaches were used to optimize each component and interface of these HTM-free metal-electrode-free devices in order to obtain a better performance. Among all these efforts, introducing 5-ammoniumvaleric acid (5-AVA) iodide into the perovskite solution of PbI2, methylammonium (MA) iodide increased the efficiency of perovskite solar cell dramatically to 12.84% (certified). The 5-AVA templating created mixed-cation perovskite (5-AVA)x(MA)1-xPbI3 crystals with lower defect concentration and better pore filling as well as more complete contact with the TiO2 scaffold, resulting in a longer exciton lifetime and a higher quantum yield for photoinduced charge separation as compared to MAPbI3. However, the fill-factor of the perovskite solar cell based on this material is limited due to the insulating nature of non-conjugated amino acid. The aim of this proposal is to design and develop a series of conjugated bi-functional molecules and apply them in the printable perovskite solar cells. In this project, we will search for new bi-functional small molecules using theoretical methods, such as density functional theory (DFT), time-dependent DFT calculations by Gaussian 09 as well as the Vienna Ab initio simulation package (VASP) and Quantum ESPRESSO. We will also explore a few series of bi-functional small molecules to reveal the mechanism. Based on both experimental and theoretical results, the novel bi-functional small molecules will be used in the mix-cation perovskite materials and applied to hole-conductor-free, fully-printable mesoscopic perovskite solar cells using carbon back contact. After optimization of the devices, it is expected to reach a fill factor of 0.75 and further improve the efficiency of these hole-conductor-free, fully-printable mesoscopic perovskite solar cells using carbon back contact without sacrifice of the stability.

基于印刷技术及介孔碳电极的钙钛矿太阳能电池，适应了光伏市场对廉价太阳能电池技术的需求。其中，一种以两性分子改性的钙钛矿材料(5-AVA)x(MA)1-xPbI3，应用于这种可印刷钙钛矿太阳能电池中，获得了12.84%的公证光电转换效率和目前已报道的钙钛矿电池里最好的稳定性，但这类电池的填充因子受5-AVA的绝缘性限制。本项目拟开发一系列共轭两性小分子，制备新型混合阳离子钙钛矿吸光材料，应用在可印刷钙钛矿太阳能电池中。首先，结合理论计算和实验，揭示5-AVA提高钙钛矿电池性能的机理，为设计和合成新型的两性分子提供理论指导；然后，设计和合成一系列共轭两性小分子，制备新型混合阳离子型钙钛矿材料，改善钙钛矿在介孔材料中的填充和结晶以及钙钛矿材料和二氧化钛界面，提高电子传输效率；最后，对基于这种新型材料的可印刷钙钛矿太阳能电池进行优化，获得填填充因子达到0.75、光电转换效率达到16%的电池器件。

近年来，钙钛矿太阳能电池凭借高效率及成本优势受到了科学家的广泛关注，在众多太阳能电池中脱颖而出。其中，可印刷介观钙钛矿太阳能电池的特点是在FTO导电玻璃上丝网印刷介孔二氧化钛层、介孔氧化锆层、多孔碳电极作为骨架材料，最后填充钙钛矿材料，完成器件的制作。这种可印刷介观PSC的所有组成部分都可以使用丝网印刷或狭缝涂覆的方法制备，在工业规模和高生产率的大面积制备上具有优势，然而在器件效率上与其他结构钙钛矿太阳能电池尚有差距。 . 本项目围绕钙钛矿太阳能电池光电转换相关基础科学问题，基于新材料的设计与开发，制备新型混合阳离子钙钛矿吸光材料，应用在可印刷介观钙钛矿太阳能电池中，提高电池器件的光电转换效率、稳定性，并做放大化尝试。具体开展了以下三个方面的工作：.(1)针对无空穴传输材料型可印刷介观钙钛矿太阳能电池，开发了一系列混合阳离子钙钛矿材料和添加剂，改善钙钛矿材料的光电性能以及各界面处的能级匹配，提高可印刷介观钙钛矿太阳能电池的效率和稳定性；.(2)基于钙钛矿溶液结晶相转变原位追踪和分析，研究了钙钛矿在介孔限域条件下的结晶过程和调控策略，实现钙钛矿在整个介孔结构中的高质量生长，提升可印刷介观钙钛矿太阳能电池的光电转换效率和稳定性；.(3)基于开发的材料和工艺手段，制备了大面积钙钛矿太阳能电池模组。. 基于这些工作，开发了具有自主知识产权的光电功能材料，将可印刷介观钙钛矿太阳能电池的第三方公证效率提升至17.7%，通过了1000 小时的湿热稳定性测试、200次冷热循环稳定性测试、2000小时的户外稳定性等；在国际高档次学术期刊上共发表论文34篇，包括Science 1篇，Joule 1篇，Advanced Materials 1篇，Advanced Energy Materials 2篇，Advanced Functional Materials 1篇，Science China Chemistry 1篇，其中3篇论文被选为ESI高被引论文，1篇论文为热点论文；申请发明专利5项，授权1项；培养3名研究生，其中1名毕业，获国家奖学金，指导4名本科生完成本科毕业设计。在各项指标上均超额完成项目。

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