有机太阳能电池由于具有制备工艺简单、质轻、机械柔性好等优点，近年来受到了广泛的关注。体异质结有机太阳能电池的活性层是决定器件光电转换效率（PCE）的关键部分，它通常由电子给体材料和电子受体材料共混组成。非富勒烯稠环电子受体因其化学结构设计性强，光学带隙和能级结构易调控等优势而备受关注，目前基于非富勒烯稠环电子受体的单层体异质结有机太阳能电池的PCE已超过19%。为了进一步提高其光伏性能，可以通过改变其化学结构包括中心核修饰、侧链修饰、端基修饰、不对称构型设计等策略进行调控，本论文主要围绕基于萘基茚酮端基的非富勒烯受体分子的设计、合成及光伏性能开展研究，通过端基氟化、中心核侧链调控等策略来探究分子结构与器件性能的关系，具体内容如下：
1. 以萘基茚酮为端基，设计、合成了四种非富勒烯稠环电子受体，分别为S1-N1F、S1-N2F、S2-N1F和S2-N2F。通过在萘基茚酮端基上引入吸电子的F原子和调节中心核上的侧链，来调控分子的最高占据分子轨道（HOMO）能级。当它们与给体聚合物PBDB-T共混制作器件，给受体之间HOMO偏移（HOMO offsets）分别为0、0.03、0.04和0.06 eV。HOMO offset为0 eV的PBDB-T:S1-N1F器件由于缺乏足够的电荷分离驱动力，最终获得较低的短路电流密度（JSC）和填充因子（FF）值，PCE仅有7.94%；尽管基于PBDB-T:S1-N2F器件具有接近零的HOMO offset（0.03 eV），但足以实现快速高效的空穴转移，最终器件的PCE高达13.59%，FF可达74.30%；基于PBDB-T:S2-N1F和PBDB-T:S2-N2F器件具有较大HOMO offset，呈现出更快的界面空穴转移过程但同时也具有较高的电荷复合，因此基于PBDB-T:S2-N1F和PBDB-T:S2-N2F的器件未能表现出突出的光伏性能（PCE分别为10.35和11.59%）。结果表明，具有接近零的HOMO offset的PBDB-T:S1-N2F共混体系仍可获得高性能的器件。
2. 以萘基茚酮和降冰片烯基茚酮为端基，设计、合成了两种端基不对称的非富勒烯稠环电子受体C8-CBIC-N2F和C11-CBIC-N2F。与两端都为降冰片烯基茚酮端基的对称分子C8-CBIC相比，双氟萘基茚酮端基的引入使分子C8-CBIC-N2F和C11-CBIC-N2F的光学吸收明显红移，光学带隙变窄，其器件具有更宽的EQE响应范围。同时双氟萘基茚酮端基的引入有效调节了分子堆积使其具有更高的载流子迁移率，有利于提高器件的JSC和FF，最终PBDB-T:C8-CBIC-N2F器件获得12.83%的PCE，高于基于对比分子C8-CBIC的器件（PCE为10.32%）。通过进一步调控分子中心核烷基链，获得分子C11-CBIC-N2F，PBDB-T:C11-CBIC-N2F具有理想的共混膜形貌，呈现纳米纤维网络结构，最终基于PBDB-T:C11-CBIC-N2F的器件表现出最佳的光伏性能，PCE为14.99%。结果表明，双氟萘基茚酮端基的引入可以拓宽吸收光谱、增强分子堆叠、有利于共混膜中载流子的传输，最终提升器件的性能。

In recent years, organic solar cells (OSCs) have attracted extensive attention due to their advantages such as simple preparation process, light weight and good mechanical flexibility. The active layer of bulk heterojunction organic solar cells (BHJ OSCs) is the key part for the power conversion efficiency (PCE) of devices, which consists of a blend of electron donor material and electron acceptor material. Nonfullerene acceptors (NFAs) have attracted much attention due to their advantages such as strong design of chemical structure, easy regulation of optical band gap and energy level structure. At present, the PCE of single junction BHJ OSCs based on NFAs has exceeded 19%. In order to further improve photovoltaic performance of NFAs, it can be regulated by changing the chemical structure, which including central nucleus modification, side chain modification, terminal group modification, asymmetric configuration design and other strategies. This paper mainly focuses on the design, synthesis and photovoltaic performance of NFAs based on naphthylindenone terminal group, and obtains high performance organic photovoltaic materials. To explore the relationship between molecular structure and device performance through strategies such as terminal group fluorination and central core side chain regulation. The results are summarized as follows:
1.We designed and synthesized four kinds of nonfullerene fused-ring electron acceptors based on naphthylindenone terminal group, namely S1-N1F, S1-N2F, S2-N1F and S2-N2F. The highest occupied molecular orbital (HOMO) offset can be adjusted continuously by introducing an electron-absorbing F atom on the naphthyl indenone terminal group and adjusting the central nuclear side chain. When they were mixed with PBDB-T, HOMO offsets were 0, 0.03, 0.04, and 0.06 eV, respectively. The PBDB-T:S1-N1F-based OSCs with HOMO offset of 0 eV shows the lowest short circuit current density (JSC) and filling factor (FF) are the lowest, resulting in an unsatisfactory PCE of 7.94%, due to unenough driving force for effective charge separation. Although the HOMO offset of PBDB-T:S1-N2F is close to zero (0.03 eV), it is sufficient to achieve rapid and efficient hole transfer. PBDB-T:S1-N2F-based OSCs give the highest PCE of 13.59% with a comparable FF up to 74.30%. In addition, blending films with large HOMO offset show faster interfacial hole transfer process but also have higher charge recombination. Therefore, devices based on PBDB-T:S2-N1F and PBDB-T:S2-N2F fail to show outstanding photovoltaic performance (PCE of 10.35 and 11.59%, respectively). The results show that PBDB-T:S1-N2F blend with near zero HOMO offset can obtain high performance devices.
2. We designed and synthesized two kinds of nonfullerene fused-ring electron acceptors with asymmetric terminal groups (naphthylindenone and norbornenylindenone as the terminal groups, respectively), namely C8-CBIC-N2F and C11-CBIC-N2F. Compared with the symmetrical molecule C8-CBIC with norbornenylindenone as terminal group, the optical absorption of C8-CBIC-N2F and C11-CBIC-N2F was significantly redshifted and the optical band gap narrowed due to the introduction of difluoronapindenone terminal group, and the device had a wider EQE response range. At the same time, the introduction of difluoronafindenone terminal group can effectively regulate the molecular stacking and make it have higher carrier mobility, which is conducive to improving the JSC and FF of the device. PBDB-T:C8-CBIC-N2F-based OSCs shows the PCE of 12.83%, which is higher than PBDB-T:C8-CBIC-based OSCs (10.32%). By further regulating the nuclear alkyl chain, the molecule C11-CBIC-N2F was obtained. PBDB-T:C11-CBIC-N2F blend has the ideal film morphology and presents the structure of nanofiber network. Therefore, PBDB-T:C11-CBIC-N2F-based OSCs show the best photovoltaic performance, with PCE of 14.99%. The results show that the introduction of difluoronafindenone terminal group can broaden the absorption spectrum, increase molecular stacking, facilitate the transport of charge carriers in the blend film, and finally improve the performance of the device.