基于苯并噻二唑衍生物的钙钛矿太阳能电池空穴传输材料的合成及性能研究

Solar cells based on organic-inorganic hybrid perovskites have aroused widespread interests owing to their high efficiency and low cost. Up to date, most of the efficient perovskite solar cells involve organic hole transport materials (HTMs). Among these organic materials, the Spiro-OMeTAD (2,2-7.7-tetrakis(N,N’-diparamethoxy-phenylamine 9,9’-spirobifluorene) is the most popular one and have attracted wide attention. However, there are still some disadvantages of this material. The high synthetic cost is one of the major obstacles to commercialize the perovskite solar cells. In addition, ionic additives or p-type dopants (Li-TFSI, lithium bis(trifluoromethylsulfonyl)-imide) are required for Spiro-OMeTAD to increase its carrier densities. As in the pristine state, the Sprio-OMeTAD has low hole density and conductivity, and a fact existed is that these additives are detrimental to the perovskite layers. Therefore, it is urgent and necessary to develop new HTM with high hole mobilities (especially in the absence of dopants), matched energy levels with the perovskite, good stability and low costs. Here in this project, through rational design of the benzothiadiazole(or fluorinated benzothiadiazole)-based HTMs, we hope to increase the hole mobility, to improve the solar cell performances, and to promote the device stability. Our work on this project will enrich the present studies toward HTMs, and provide new sights into design and synthesis of efficient HTMs. We believe that this research will play an important role in theoretical understanding as well as applications of perovskite solar cells.

钙钛矿太阳能电池因其光电转换效率高、成本低等优点备受关注。在已报道的高效率的钙钛矿太阳能电池中，往往都离不开好的空穴传输材料。目前应用最为广泛的空穴传输材料为Spiro-OMeTAD，但是这种材料也具有难以克服的缺点，如合成工艺复杂，价格高，且掺杂才能获得好的空穴传输能力等。因此，开发空穴传输性能良好（特别是在不掺杂条件下）、能级与钙钛矿相匹配、稳定性好、成本低廉的有机小分子作为钙钛矿太阳能电池的空穴传输材料尤为重要。本项目在申请人前期工作的基础上，通过对苯并噻二唑（或氟代苯并噻二唑）为核心的结构进一步功能化，旨在提高其空穴传输能力，从而实现更高的光电转化效率，并探索非掺杂空穴传输材料的合成同时提升器件的稳定性。本项目的开展，将丰富有机小分子空穴传输材料体系的研究，并从空穴传输材料的角度为提高钙钛矿电池效率提供新的思路，这对于钙钛矿太阳能电池的理论研究和实际应用具有非常重要的意义。

钙钛矿太阳能电池因兼具高光电转换效率和低制备成本等优点备受关注。空穴传输材料是制备高效、稳定钙钛矿太阳能电池的关键要素之一。开发空穴传输性能良好（特别是在不掺杂条件下）、能级与钙钛矿相匹配、稳定性好、成本低廉的有机小分子作为钙钛矿太阳能电池的空穴传输材料尤为重要。按照项目申请时拟定的方案，首先我们开展了对基于苯并噻二唑衍生物的钙钛矿太阳能电池空穴传输材料的研究。通过对苯并噻二唑（或氟代苯并噻二唑）为核心的结构进一步功能化，构建了一系列新型空穴传输材料，以它们制备的钙钛矿电池最高可获得19.14 %的光电转换效率，器件稳定性也得到了一定的提升。接着，我们分别以四苯乙烯、联吡啶、二吡啶甲酮、四苯乙烯、二苯并[a，c]咔唑、荧蒽等基团为核继续深入开发新的空穴传输材料，并成功将它们应用于钙钛矿电池器件中，光电转换效率超过21 %。此外，作为本项目的延伸，我们也对钙钛矿电子传输材料的研究开展了尝试。设计并合成了一系列基于ITIC、PDI结构的有机电子传输材料，将它们应用于p-i-n结构钙钛矿电池器件中，最高获得了21 %以上的光电转换效率。依托本项目的资助，项目负责人以第一作者或通讯联系人已发表Angew. Chem. Int. Ed.，Adv. Mater.，Adv. Funct. Mater.，ACS Energy Lett.，Chem. Sci.，J. Mater. Chem. A等期刊在内的SCI论文共计30篇（其中第一顺序标注的21篇），申请并授权专利1项。通过本项目的开展实施，丰富了有机小分子空穴传输材料体系的研究，并从空穴传输材料的角度为提高钙钛矿电池效率提供了新的思路，也取得了一些有意义的研究成果，为相关工作的分子设计、合成积累了丰富的经验。