在当今能源需求不断增长与传统能源面临枯竭及环境问题的背景下，太阳能作为一种清洁、可再生能源受到广泛关注。有机太阳能电池(OSCs)由于质轻、柔性、半透明以及可大面积加工等特点，在可穿戴电子设备和建筑光伏一体化等领域展现出巨大的应用潜力。非富勒烯受体(NFAs)由于其独特的结构可调性和光电性能可控等优点而备受关注，特别是基于受体-给体-受体’-给体-受体(A-DA’D-A)型的Y系列稠环小分子受体在2019年后成为研究的重点。喹喔啉是一种弱缺电单元，与Y系列稠环小分子经常采用的苯并三唑和苯并噻二唑等A’单元相比，具有丰富的结构可调性。本研究设计并制备了基于喹喔啉结构的Y型稠环分子，系统研究了这些材料的光物理特性以及光伏性能，并对光伏器件的电荷传输与复合机理以及薄膜的形貌和分子取向性等进行了研究。

首先，以2,3-二(3-辛氧基苯基)二噻吩并[3,2-f:2',3'-h]喹喔啉为缺电子单元，制备了两种分别以氟溴氰基茚酮(FBr-IC)为端基的对称受体材料BQ-2FBr和以两氯氰基茚酮(2Cl-IC)及氟溴氰基茚酮(FBr-IC)为端基的非对称受体材料BQ-2Cl-FBr。对称的BQ-2FBr具有较高的LUMO能级，而非对称分子BQ-2Cl-FBr则展现出更宽的吸收光谱、较高的摩尔消光系数以及更好的π-π堆积性能。与PM6结合时，BQ-2FBr器件实现了0.944 V的优异开路电压和10.11%的中等光电转换效率。尽管BQ-2Cl-FBr器件的开路电压略有下降，为0.928 V，但短路电流密度和填充因子同时得到改善，使得PCE提高到11.54%。这主要归因于激子解离和电荷收集性能的提升、电荷复合的抑制、分子堆积性能的增强、薄膜形态的优化以及激子扩散时间的加快。

其次，将苊环和溴苊烯环引入A-DA’D-A受体体系中，合成了基于二维稠环拓展新核的小分子受体C₁₂BE-4F和C₁₂BE-Br-4F。基于苊环喹喔啉中心核C₁₂BE-4F具有较低的LUMO能级，而基于溴苊烯环喹喔啉中心核C₁₂BE-Br-4F展现出更宽的吸收光谱和较高的LUMO能级。与聚合物PM6结合制备二元器件时，C₁₂BE-4F器件实现了0.933 V的开路电压，22.16 mA cm^-2的高短路电流密度，66.27%的高填充因子和13.69%的中等光电转换效率。制备基于PM6:BTP-eC9三元器件时，虽然PM6:BTP-eC9:C₁₂BE-4F三元器件开路电压略有降低，为0.844 V，但短路电流密度和填充因子均有提升分别为28.36 mA cm^-2和76.75%，实现了18.37%优异PCE，这主要归因于电荷收集性能的提升、电荷复合的抑制以及薄膜形貌的优化。

最后，成功合成了两种新型的喹喔啉基多臂受体材料，C₁₂QX-B和C₂₀QX-B。这些分子由吡嗪喹喔啉单元桥连接，以具有弱拉电子特性的1,3-二乙基-2-硫代巴比妥酸作为端基。基于长烷基链四臂材料C₂₀QX-B展现出更宽的吸收光谱和较低的LUMO能级，而基于短烷基链四臂材料C₁₂QX-B具有较高的LUMO能级。将C₁₂QX-B和C₂₀QX-B引入PM6:BTP-eC9体系中制备三元器件，PM6:BTP-eC9:C₂₀QX-B三元器件达到17.17%的PCE，而PM6:BTP-eC9:C₁₂QX-B三元器件实现了18.23%的优异PCE，这两种四臂受体材料三元器件的PCE均高于PM6:BTP-eC9二元器件的16.91%。两种三元器件性能提升的差异主要是由于两种小分子对三元薄膜的空穴迁移率提升和电子迁移率的抑制程度不同所致。

In the context of the continuously growing energy demand, the depletion of traditional energy sources, and environmental issues, solar energy, as a clean and renewable energy source, has received extensive attention. Organic solar cells (OSCs), due to their characteristics such as light weight, flexibility, semi-transparency, and the ability to be processed over a large area, exhibit great application potential in fields such as wearable electronic devices and building-integrated photovoltaics. Non-fullerene acceptors (NFAs) have attracted much attention due to their unique advantages such as structural tunability and controllable optoelectronic properties. In particular, the Y-series fused-ring small-molecule acceptors of the acceptor-donor-acceptor-donor-acceptor (A-DA’D-A) type have become the focus of research after 2019. Quinoxaline is a weakly electron-deficient unit. Compared with the A’ units such as benzotriazole and benzothiadiazole, which are often used in the Y-series fused-ring small molecules, it has rich structural tunability. In this study, materials based on the quinoxaline structure were designed and prepared by changing the alkyl chains and terminal groups. The photophysical properties and photovoltaic performance of these materials were systematically studied. Additionally, the charge transport and recombination mechanisms of the photovoltaic devices, as well as the morphology and molecular orientation of the thin films, were investigated.

Firstly, using 2,3-bis(3-octyloxyphenyl)dithieno[3,2-f:2',3'-h]quinoxaline as the electron-deficient unit, two acceptor materials were prepared. One is the symmetric acceptor material BQ-2FBr with fluorobromocyanoindanone (FBr-IC) as the terminal group, and the other is the asymmetric acceptor material BQ-2Cl-FBr with dichlorocyanoindanone (2Cl-IC) and fluorobromocyanoindanone (FBr-IC) as the terminal groups. The BQ-2FBr molecule, which exhibits a symmetrical structure, possesses a higher LUMO energy level. In contrast, the asymmetric BQ-2Cl-FBr molecule features a more expansive absorption spectrum, augmented molar extinction coefficient, and enhanced π-π stacking characteristics. In conjunction with PM6, the BQ-2FBr device attains an exceptional open-circuit voltage of 0.944 V and a commendable photovoltaic conversion efficiency of 10.11%. Despite a slight decrease in the open-circuit voltage of the BQ-2Cl-FBr device to 0.928 V, simultaneous enhancement in the short-circuit current density and fill factor has been observed, culminating in an augmented PCE of 11.54%. This enhancement is attributed to a combination of factors, including enhanced exciton dissociation and charge collection performance, suppression of charge complexation, enhanced molecular stacking performance, optimized film morphology, and faster exciton diffusion time.

Secondly, acenaphthene rings and bromoacenaphthylene rings were introduced into the A-DA’D-A acceptor system, and small-molecule acceptors C₁₂BE-4F and C₁₂BE-Br-4F based on a new two-dimensional fused-ring extended core were synthesized. The introduction of bromoacenaphthylene rings led to enhanced aggregation of the small-molecule acceptors, resulting in the blend films based on bromoacenaphthylene rings having larger phase separation sizes and surface roughness. When combined with polymer PM6 for the preparation of binary devices, the C₁₂BE-4F devices achieved an open-circuit voltage of 0.933 V, a high short-circuit current density of 22.16 mA cm^-2, a high fill factor of 66.27% and a moderate power conversion efficiency of 13.69%. For the ternary devices based on PM6:BTP-eC9 binay system, while the open-circuit voltage of the PM6:BTP-eC9:C₁₂BE-4F device is marginally reduced to 0.844 V, there is an enhancement in both the short-circuit current density and the fill factor to 28.36 mA cm^-2 and 76.75%, respectively, and an excellent PCE of 18.37% is achieved. This enhancement is primarily ascribed to the enhanced charge collection performance, the suppression of charge compounding, and the optimization of film morphology.

Finally, the synthesis of two novel quinoxaline-based multi-armed receptor materials, C₁₂QX-B and C₂₀QX-B, had been successfully achieved. These molecules are bridged by pyrazine-quinoxaline units with 1,3-diethyl-2-thiobarbituric acid, which possesses a weak electron-pulling property, as an end group. The long alkyl chain four-arm based material C₂₀QX-B exhibits a broader absorption spectrum and a lower LUMO energy level, while the short alkyl chain four-arm based material C₁₂QX-B has a higher LUMO energy level. Upon introduction of both C₁₂QX-B and C₂₀QX-B into the PM6:BTP-eC9 system for the preparation of ternary devices, the PM6:BTP-eC9:C₂₀QX-B device attained a PCE of 17.17%, whereas the PM6:BTP-eC9:C₁₂QX-B device achieved an excellent PCE of 18.23%, and the ternary devices of both four-arm acceptor materials had a PCE that is higher than the 16.91% of the PM6:BTP-eC9 binary device. It can thus be concluded that the discrepancy in the performance enhancement of the two four-arm acceptor-based ternary devices is primarily attributable to the varying degree to which the enhancement of hole mobilities and the inhibition of electron mobilities of the ternary films caused by these two small molecules.

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