第三代太阳能电池主要指在第二代薄膜太阳能电池的制程中引入有机半导体材料和纳米技术。近几年，有机-无机杂化的钙钛矿薄膜太阳能电池出现并得到迅速发展，较为成熟的有机本体异质结太阳能电池的制备工艺快速迁移到钙钛矿薄膜太阳能电池的制备过程上，使得钙钛矿薄膜太阳能电池的效率在较短的时间内突破了22％。与此同时，有机光伏材料的研究也在稳步发展，随着新型高效的非富勒烯衍生物类受体材料ITIC的出现，基于非富勒烯衍生物类受体材料的单层有机太阳能电池效率目前也已经突破了14％。 有机太阳能电池的发展主要依托有机光伏材料的开发，通过制备并且优化基于新型光伏材料的有机太阳能电池，对有机光伏材料进行系统表征与研究，是开发高效有机太阳能电池过程中十分的重要一部分。本文围绕有机光伏材料，通过制备有机太阳能电池，对材料的光伏性质及影响有机太阳能电池效率的因素进行了深入研究与分析。取得的主要研究成果如下： 1.通过使用向前躯体溶液中加入少量的碘化铵(NH₄I)的方法来提高基于醋酸铅(PbAc₂)铅源的钙钛矿薄膜太阳能电池的活性层质量，从而提高钙钛矿薄膜太阳能电池器件的功率转换效率(PCE)。我们将没有经过退火处理(静置在手套箱24h)的钙钛矿太阳能电池平均8.98％的PCE提高到平均13.69％。然后我们利用扫描电子显微镜(SEM)与原子力显微镜(AFM)仔细研究含有不同NH₄I添加量的基于PbAc₂的前驱体溶液形成的钙钛矿太阳能电池活性层的表面形态，并利用X射线衍射技术来分析钙钛矿太阳能电池X-射线衍射图谱(XRD)来研究钙钛矿活性层的结晶情况。我们实验结果表明，NH₄I作为一种添加剂可以加速基于PbAc₂的钙钛矿薄膜中晶体的生长和聚集，减少钙钛矿太阳能电池活性层的断裂，促进钙钛矿活性层在ITO／PEDOT-PSS层上形成均匀连续的薄膜，从而提高基于PbAc₂钙钛矿太阳能电池的效率。 2.以双(烷硫基-噻吩基)苯并二噻吩为给体单元、氟取代的苯并三氮唑为受体单元与噻吩为π桥的中间带隙D-A型聚合物给体材料J61与n型窄带隙有机半导体受体材料ITIC制成单层异质结型的非富勒烯聚合物太阳能电池(PSC)表现出优异的光伏性能。为了研究这类D-A型聚合物给体材料中π桥对其光伏性能的影响，我们合成了与J61的给体单元和受体单元相同，只是π桥由噻吩换成呋喃的聚合物给体材料J61-F。与J61的-5.32eV的最高占据分子轨道(HOMO能级)相比，J61-F具有更低的-5.43eV的HOMO能级。基于J61-F:ITIC的单层本体异质结型的非富勒烯聚合物太阳能电池具有更高的开路电压(V〓)，约为0.95V，电池的最大光电转换效率(PCE)为8.24％。我们的实验结果表明，利用改变兀桥的主链工程技术，可以调节共轭D-A型聚合物给体材料的HOMO能级，是一种切实有效可行的调控聚合物给体光伏材料能级的方法。 3.在含烷氧基的苯并二噻吩(BDT)与含氟的苯并三氮唑(FBTA)的给体(D)受体(A)单元的基础上，以噻吩并[3,2-b]噻吩(TT)为π桥，合成了新型J-系列D-A型聚合物给体材料J41。与其相应的具有噻吩π桥的D-A型聚合物给体材料J40相比，J41具有更低的HOMO能级，约为-5.39eV，并且其光谱吸收也出现了轻微地蓝移。以J41为PSC的给体材料，以窄带隙n型有机半导体(n-OS)ITIC作为受体材料的单层异质结结构(BHJ)PSC表现出较高的V〓，约为0.93V，基于J41:ITIC的PSC的最大光电转换效率(PCE)为8.74％，而与其对应的以J40作为给体材料、ITIC为受体材料的非富勒烯PSC的V〓仅为0.89V，最大PCE仅为6.48％，J41材料的光伏性能得到了显著提高。我们的实验结果表明，π桥工程可以进一步提高基于BDT-FBTA的D-A型聚合物给体材料的光伏性能。 4.通过在苯[1,2-b:4,5-b]并二噻吩(BDT)单元上引入噻吩并[3,2-b]噻吩(TT)共轭侧链，与氟苯并三氮唑(FBTA)共聚，设计并合成了两种新的D-A共聚物给体材料J46和J47。J46的TT共轭侧链上具有烷基取代基，J47的TT侧链上具有烷基硅烷基取代基。以J47为PSC给体材料、ITIC为受体材料制成的单层本体异质结PSC，通过使用DIO添加剂和热退火工艺(在150℃的热台上热退火2分钟)处理的J47:ITIC的PSC的光电转换效率(PCE)达到9.0％，而基于J46:ITIC的PSC的PCE仅为2.33％。结果表明，J-系列BDT-FBTA共聚物中共轭侧链的大小和性质显著影响二维共轭聚合物的物理化学和光伏特性，通过改变共轭侧链的大小与性质的侧链工程技术，是改进2D共轭聚合物给体材料的光伏性能有效方法。 关键词：钙钛矿太阳能电池，碘化铵(NH₄I)添加剂，聚合物太阳能电池，共轭聚合物给体光伏材料，噻吩并[3,2-b]噻吩共轭侧链

Third-generation solar cells mainly refer to solar cells made of organic semiconductor materials and (or) by nanotechnology in the fabrication of thin film (“second generation”) solar cells. In recent years, organic-inorganic hybrid perovskite materials have been recognized as a promising light-absorbing material for third-generation solar cells, and the power conversion efficiency of the perovskite solar cells has reached over 22%. At the same time, research on organic photovoltaic materials has been made steadily progressing. With the emergence of novel and efficient n-type organic semiconductor (n-OS) ITIC, the power conversion efficiency of single-junction polymer solar cells (PSCs) based on nonfullerene acceptors has exceeded 14%. The development of PSCs mainly relies on the development of organic photovoltaic materials. By preparing and optimizing PSCs based on new photovoltaic materials, the characterization and research on organic photovoltaic materials is a very important part of the process of developing efficient PSCs. This thesis mainly focuses on the characterization and studies of organic photovoltaic materials. The properties of the new photovoltaic materials and the factors that affect the PCE of the PSCs were thoroughly studied. The main results obtained are as follows: 1.We found a simple, practical and energy-conserving way to improve the active layer quality of the perovskite solar cells prepared from lead acetate (PbAc₂) and thus to boost the efficiency. Through adding a small amount of ammonium iodide (NH₄I) to the precursor solution, a higher average PCE of 13.69% was obtained, which is significantly improved from the average power conversion efficiency (PCE) of 8.98% for the pristine devices. The morphology of the perovskite active layer from the precursor solutions with various amounts of additive then was carefully studied by SEM, XRD, and AFM. The results indicate that the additive of NH4I can accelerate the growth and aggregation of perovskite crystals, reduce the fractures of the perovskite films and promote the formation of a continuous uniform thin film on ITO/PEDOT:PSS layer. 2.The medium band gap donor-acceptor (D-A) copolymer J61 based on bi(alkylthio-thienyl)benzodithiophene as donor unit and fluorobenzotriazole (FBTA) as acceptor unit and thiophene as π-bridge has demonstrated excellent photovoltaic performance as donor material in nonfullerene polymer solar cells (PSCs) with narrow bandgap n-OS ITIC as acceptor. For studying the effect of π-bridges on the photovoltaic performance of the D-A copolymers, we synthesized a new D-A copolymer J61-F based on the same donor and acceptor units as J61 but with furan 71-bridges instead of thiophene. J61-F possesses a deeper HOMO (the highest occupied molecular orbital) level at -5.43 eV in comparison with that (-5.32 eV) of J61. The non-fullerene PSCs based on J61-F: ITIC exhibited a maximum PCE of 8.24% with a higher V〓 (open-circuit voltage) of 0.95 V, which is benefitted from the lower-lying HOMO energy level of J61-F donor material. The results indicate that main chain engineering by changing π-bridges is another effective way to tune the electronic energy levels of the conjugated D-A copolymers for the application as donor materials in nonfullerene PSCs. 3.A new J-series D-A copolymer J41 based on alkoxy-benzodithiophene (BDT)-alt- FBTA was synthesized with thieno[3,2-b]thiophene (TT) as π-bridges. In comparison with its corresponding D-A copolymer J40 with thiophene π-bridges, J41 shows a deeper HOMO energy level of -5.39 eV and slightly blueshifted absorption. The polymer solar cells (PSCs) with J41 as donor and ITIC as acceptor exhibited a maximum PCE of 8.74% with a higher V〓 of 0.93V, which is significantly improved in comparison with the PCE of 6.48% with Voc of 0.89 V for the corresponding PSCs with J40 as donor. The results indicate that the π-bridge engineering could further improve photovoltaic performance of the BDT-alt-FBTA-based D-A copolymers. 4.We designed and synthesized two new D-A copolymers J46 and J47 through replacing thiophene conjugated side chains by thieno[3,2-b]thiophene (TT) in the benzo[l,2-b:4,5-b’]dithiophene (BDT) units copolymerized with FBTA. J46 possesses alkyl substituent on the TT conjugated side chains and J47 with alkylsilyl substituent on the TT side chains. PCE of the PSCs based on J47 as donor and ITIC as acceptor with thermal annealing at 150℃ for 2 min and with DIO additive treatment reached 9.0%, while the PCE of the J46-based PSCs was only 2.33%. The results indicate that the size and nature of the conjugated side chains in the J-series BDT-alt-FBTA copolymers influence the physicochemical and photovoltaic properties of the 2D-conjugated polymers significantly, and the side chain engineering could play an important role in improving the photovoltaic performance of the 2D-conjugated polymer donor materials. Key Words: Perovskite solar cells, NH₄I additive treatment. Polymer solar cells, Conjugated polymer donor photovoltaic materials, Thieno[3,2-b]thiophene conjugated side chains