基于噻吩酰亚胺构建单元的新型有机界面材料的制备及其在钙钛矿电池中的应用

The past decade has witnessed remarkable advances in perovskite solar cells (PeSCs) whose power conversion efficiencies (PCEs) have rivalled those of silicon-based solar cells. This strongly implies a promising future towards commercialization of solar cells involving large-area process and flexible functions. In solution-processed inverted PeSCs, fullerene and its derivatives have been used as dominated electron-transporting layers, however, high cost for production and difficulty in purification limit their application in large-area manufacture. Therefore, it is highly important to develop a new series of electron-transporting interficial materials to replace fullerene and its derivatives. In this project, 3,3’-bithiophene imide will be adopted as basic building block, linked to conjugated π bridges. The basic optoelectronic properties such as energy level and electron mobility can be tuned through rational design of π bridges. Additionally, the sulfur atoms in thiophene rings can induce weak coordination interactions with Pb ions, while lone pair electrons of carbonyl groups can passivate defects of perovskite interfaces, both of which can enhance the electron extraction from perovskite layer. We believe that higher PCEs can be achieved for these new electron-transporting interfacial materials based PeSCs compared with those of fullerene and its derivatives based PeSCs, so that a new avenue for non-fullerene based PeSCs can be established and theoretical and experimental basis for studying the structure-property relationships of electron-transporting interfacial materials can be provided.

钙钛矿太阳能电池在过去十年间发展迅猛，光电转换效率已可匹敌硅基太阳能电池，为未来基于大面积工艺和柔性功能的太阳能电池产业化开辟了新的方向。在可溶液加工的倒置型钙钛矿电池中，富勒烯及其衍生物作为电子传输层占据着不可动摇的地位。然而，其昂贵的造价和较困难的提纯工艺制约了钙钛矿电池的大面积制备。针对这一问题，本项目旨在开发一系列可取代富勒烯及其衍生物的新型有机电子传输界面材料。它们以3,3'-联噻吩酰亚胺为基本构建单元，键接于不同类型的共轭π桥之上。噻吩环的硫原子以及酰亚胺羰基上的孤对电子均可与铅离子形成弱相互作用，从而钝化钙钛矿表面缺陷，增强电子萃取能力。此外，通过共轭π桥的合理设计，分子的能级、电子迁移率、导电率等属性均可被调控。我们相信这一系列电子传输界面材料用于非富勒烯基的钙钛矿电池能获取较高的光电转换效率，从而为研究电子传输界面材料的构性关系提供理论基础和实验依据。

作为绿色环保的一项新能源开发技术，第三代可溶液加工型太阳能电池从上世纪90年代兴起发展至今，已取得了巨大的进步，其中有机太阳能电池和钙钛矿电池的发展尤为迅猛。尽管如此，有机太阳能电池中的大多数非富勒受体材料合成路线较长，制备成本较高，且器件普遍需要添加剂，而钙钛矿电池中的常用的空穴传输材料也存在制备成本较高、本征态空穴传输性能较低等问题。.针对上述问题，本项目从以下两个方面展开研究：1）低成本非富勒烯受体材料的研发：本项目采用原料易得的多环芳烃作为构建单元，设计合成了一系列新型非富勒烯小分子受体材料，并系统性地研究其化学结构、光电属性、膜态形貌以及太阳能器件性能之间的关系，其中以芘为构建单元的非富勒受体分子用于无添加剂的有机太阳能电池中可实现10.37%的光电转换效率。该项目为构建新型简单高效的受体分子尤其是近红外受体分子提供了新的分子设计思路；2）高效稳定的空穴传输/界面材料的研发：本项目通过不同的分子设计策略如给体-受体-给体设计策略、锚定基团修饰策略、树枝化组装策略、给体-受体自组装分子设计策略等，开发出一系列高效稳定的空穴传输/界面材料，用于反式钙钛矿电池实现了21.24%的光电转换效率，打破了反式器件的效率瓶颈，同时实现效率高达20.2%的可醇溶液加工的钙钛矿器件，创造绿色溶剂加工钙钛矿电池的效率纪录。该项目为开发兼具高性能、低成本、可绿色溶剂加工的空穴传输/界面材料提供了新的指导思路。