电极界面缓冲层对P3HT:PC61BM太阳能电池热稳定性的影响

基于溶液法加工制备的聚合物太阳能电池的高温热稳定性是决定器件能否兼容后续高温热封装工艺, 如热压封装、高温原子层沉积(ALD)等的一个关键. 本文分别利用聚(3, 4-乙烯二氧噻吩)-聚苯乙烯磺酸(PEDOT:PSS)和MoO₃作为阳极缓冲层, 以及ZnO和LiF 作为阴极缓冲层, 制备了结构为氧化铟锡(ITO)/阳极缓冲层/3-己基取代聚噻吩:(6, 6)-苯基C₆₁-丁酸甲酯(P3HT:PC₆₁BM)/阴极缓冲层/Al 的太阳能电池, 系统地比较研究了不同界面缓冲材料对器件光电转换性能及稳定性的影响, 特别是在高温煺火条件下器件的性能稳定性差异. 结果表明, 聚合物太阳能电池的热稳定性同器件的结构以及所用的缓冲层材料有密切的相关性. 其中, 利用MoO₃及ZnO分别作为阳极与阴极界面修饰层的P3HT:PC₆₁BM器件在120-150 ℃的温度范围内能够较好地保持器件的光电转换性能. 这一结果为后续需要高温封装工艺的器件提供了有意义的结构优化指导. 此外, 研究结果还表明利用ZnO作为阴极缓冲层能够改善器件的长时间稳定性.     

有机太阳能电池热失效机制及三元共混提升其热稳定性研究进展

有机太阳能电池(Organic solar cells, OSCs)作为一种新兴高效太阳能电池,近年来得到飞速发展.目前OSCs的光电转换效率(Powerconversionefficiency,PCE)已经达到19%以上,初见商业化应用曙光.但其稳定性方面尚未发展成熟,尤其在制备和工作过程中电池器件需要经历高温考验,电池的热稳定性要求高.三元共混策略是在传统的二元OSCs活性层中引入第三组分,利用第三组分调控分子间的相互作用,在实现高效光电转换效率的同时有效提高器件热稳定性,展现出了极大的应用潜力.本综述首先从器件热衰减过程出发,总结了OSCs热衰减过程中包括:热致活性层形貌变化、各层材料之间的互扩散行为以及界面老化等相关机制.在此基础上,重点介绍了三元策略在提高OSCs热稳定性方面的应用进展和作用机制.最后,对三元策略在OSCs中的应用发展进行总结并展望,指出第三组分的针对性选择以及作用机制解析是三元OSCs面临的关键问题和挑战.     

聚合物太阳能电池器件热稳定性的研究进展

实现聚合物太阳能电池的商业化应用有两个关键技术因素:能量转换效率和热稳定性。 在近几年里,能量转换效率已经成功突破10%。 与此同时,器件热稳定性的研究也一直在有条不紊的展开。 本文总结了近年来在聚合物太阳能电池光敏层热稳定性的研究进展,详细阐述了提高形貌热稳定性的常用方法,并对器件热稳定性的研究进行了展望。     

以碱金属盐为阴极界面层的有机光电器件的制备及性能

以碱金属盐Li F,Na F,Cs F和Cs2CO3作为阴极界面材料,制备了高效率有机小分子电致发光二极管(SMOLEDs)、聚合物电致发光二极管(PLEDs)及聚合物太阳能电池(PSCs).在SMOLEDs和PLEDs中,Cs F作为阴极界面层的器件流明效率和功率效率最高.在以聚对苯乙烯撑(P-PPV)为发光层的PLEDs中,Cs F作为阴极界面层的器件最大流明效率可达17.85 cd/A,比Li F作为阴极界面层的器件流明效率提高近300%.在以聚(3-己基噻吩)(P3HT)∶[6,6]-苯基-C61-丁酸甲酯(PC61BM)为活性层的PSCs中,当Li F为阴极界面层时,器件功率转换效率(PCE)可达4.12%.而以Na F,Cs2CO3和Cs F为阴极界面层时,PCE分别为3.72%,3.55%和3.2%.这是因为从上述碱金属盐中分解出来的碱金属原子扩散进入器件的有机层并对有机层进行了n型掺杂,影响了器件的电流密度和效率.     

新型给体-受体型聚合物的合成及其在本体异质结聚合物太阳能电池中的应用

设计、合成了侧链含有强吸电结构的丙二酸二丁酯受体单元与苯并[1,2-b:4,5-b′]二噻吩给体单元交替共聚物PBDTDT,研究了其热学、光学、电化学性质以及与受体PC71BM([6,6]-苯基C71丁酸甲酯)共混作为活性层制备成本体异质结聚合物有机太阳能电池的光伏性质,考察了PBDTDT与PC71BM不同比例时的光伏性能,当聚合物PBDTDT和PC71BM质量比为1∶3制备的器件,其开路电压达到了0.82 V,能量转换效率(PCE)为0.90%,短路电流为3.25 mA/cm2,填充因子FF为0.338,同时将其与同等工艺制备的poly(3-hexylthiophene)(P3HT)太阳能电池的光伏性能进行比较,相同工艺下制备的P3HT电池的开路电压仅为0.55 V,由PBDTDT制备的电池开路电压比P3HT电池的开路电压高出0.29V,同时分析了PBDTDT能量转换效率较P3HT低的原因.     

多功能可交联材料在聚合物太阳能电池中的应用

近年来,可交联材料在有机光电器件领域,尤其是聚合物太阳能电池领域,得到了广泛的应用研究。可交联材料作为活性层中的给体材料或受体材料以及制作有序本体异质结聚合物太阳能电池,可以提高器件的稳定性及光电转化效率。可交联材料应用于聚合物太阳能电池的电子传输层或空穴传输层,可以提高器件的开路电压、转化效率、稳定性等各项性能参数。本文根据可交联材料在聚合物太阳能电池中的功能的不同,详细地描述了可交联材料的官能团种类、处理时间、温度以及引发剂等因素对聚合物太阳能电池光电性能的影响,同时评述了可交联材料应用于聚合物太阳能电池的缓冲层及制作有序本体异质结聚合物太阳能电池的研究进展,最后展望了可交联材料在该领域的发展前景。     

苝二酰亚胺聚合物受体设计及在全聚合物太阳能电池中的应用

二元或多元聚合物组成的本体异质结具备高度稳定的微相分离形貌,带来潜在的器件寿命和稳定性方面的巨大优势,全聚合物活性层器件因而成为有机太阳能电池的重要发展方向和研究内容.本文系统介绍近年来苝二酰亚胺类聚合物受体的研究进展,以及将这类聚合物受体应用于全聚合物太阳能电池所取得的重要成果.通过多种不同共聚单元结构的设计和筛选、主链和侧链化学结构的调控和优化,获得了一系列性能优越的苝二酰亚胺聚合物受体,这些材料的运用大幅度地提升了全聚合物太阳能电池的能量转化效率.相关的研究数据和结果也为后续酰亚胺类聚合物受体的设计开发、全聚合物本体异质结活性层的形貌特征和光电转化机制的分析和研究,以及全聚合物太阳能电池器件性能的优化和提升提供了良好的实验基础.     

基于4,7-二噻吩苯并噻二唑和异靛单元的受体-受体共轭聚合物的合成与光伏性质

利用微波协助的Stille缩合聚合反应方法合成了基于双噻吩苯并噻二唑和异靛单元的受体-受体聚合物HFTBT-DA865,并对其热稳定性、光物理性能、电化学性质和本体异质结太阳能电池性能进行了研究.该聚合物易溶于邻二氯苯和邻二甲苯等溶剂,具有优异的溶液加工性能.5%热分解温度为389℃,玻璃化转变温度为168℃,说明其具有较好的热稳定性能.对旋涂速度和温度进行优化,所得太阳能电池器件的光电转换效率为2.28%,开路电压为0.83 V,短路电流为-5.70 mA/cm^2,填充因子为48.9%.电化学性能和密度泛函理论估算结果表明,聚合物与受体材料PC71BM相近的最低未占分子轨道(LUMO)值及其平面性可能是影响光伏性质的重要因素.通过调控共聚单体或优化受体材料,器件性能可进一步提高.对受体-受体(A-A)类聚合物材料太阳能电池性能的研究表明,此类材料是一类潜在的聚合物太阳能电池材料.     

以C_(70)衍生物为电子受体的高效聚合物固体薄膜太阳能电池

以PC[70]BM(phenyl C71-butyric acid methyl ester)取代PC[60]BM(phenyl C61-butyric acid methyl ester)作为电子受体材料,以MEH-PPV(poly[2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene])为电子给体材料,制成了本体异质结(bulk heterojunction,BHJ)聚合物太阳能电池.MEH-PPV/PC[70]BM器件在AM1.5G(80 mW/cm2)模拟太阳光的光照条件下得到了3.42%的能量转换效率,短路电流值达到了6.07 mA/cm2,开路电压0.85 V,填充因子为53%.通过紫外可见吸收光谱和外量子效率的研究,发现PC[70]BM作为电子受体,对扩大光谱的吸收范围和增加活性层的吸收系数有明显的作用.同时比较了不同溶剂对该体系器件性能的影响.通过原子力显微镜(AFM)、光暗导I-V曲线等研究,分析了1,2-二氯苯有利于给体相和受体相的微相分离和载流子的传输的原因.     

聚合物太阳能电池活性层的形貌调控

聚合物太阳能电池由于制备工艺简单、重量轻、成本低廉、可制备大面积柔性器件等优点,成为新能源和材料科学中的重要研究方向.经过近10年的发展,聚合物太阳能电池的能量转换效率从2005年的5%提高到目前的10%左右,然而聚合物太阳能电池的活性层形貌仍是制约其能量转换效率的一个重要方面.本文围绕聚合物太阳能电池结构与性能的关系,重点介绍了活性层材料的分子设计(共轭主链调制、烷基侧链优化等)和加工方法(热退火、添加剂、三元溶剂、绿色溶剂等)对其微观形貌的影响,并展望了聚合物太阳能电池未来的发展趋势以及面临的关键挑战.     

Large open-circuit voltage polymer solar cells by poly(3-hexylthiophene) with multi-adducts fullerenes

Polymer solar cells (PSCs) made by poly(3-hexylthiophene) (P3HT) with multi-adducts fullerenes, [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM), PC61BM-bisadduct (bisPC61BM) and PC61BM-trisadduct (trisPC61BM), were reported. Electrochemistry studies indicated that PC61BM, bisPC61BM and trisPC61BM had step-up distributional lowest unoccupied molecular orbital (LUMO) energy. PSCs made by P3HT with above PC61BMs show a trend of enlarged open-circuit voltages, which is in good agreement with the energy difference between the LUMO of PC61BMs and the HOMO of P3HT. On the contrary, reduced short-circuit currents (Jsc) were observed. The investigation of photo responsibility, dynamics analysis based on photo-induced absorption of composite films, P3HT:PC61BMs and n-channel thin film field-effect transistors of PC61BMs suggested that the short polaron lifetimes and low carrier mobilities were response for reduced Jsc. All these results demonstrated that it was important to develop an electron acceptor which has both high carrier mobility, and good compatibility with the electron donor conjugated polymer for approaching high performance PSCs.     

Fullerene derivative acceptors for high performance polymer solar cells

Polymer solar cells (PSCs) are composed of a blend film of a conjugated polymer donor and a soluble fullerene derivative acceptor sandwiched between a PEDOT?:?PSS coated ITO positive electrode and a low workfunction metal negative electrode. The conjugated polymer donor and the fullerene derivative acceptor are the key photovoltaic materials for high performance PSCs. For the acceptors, although [6,6]-phenyl-C(61)-butyric acid methyl ester (PC(60)BM) and its corresponding C(70) derivative PC(70)BM are dominantly used as the acceptors in PSC at present, several series of new fullerene derivatives with higher-lying LUMO energy level and better solubility were reported in recent years for further improving the power conversion efficiency of the PSCs. In this perspective paper, we reviewed the recent research progress on the new fullerene derivative acceptors, including various PC(60)BM-like C(60) derivatives, PC(60)BM bisadduct, PC(70)BM bisadduct, indene-C(60) bisadduct and indene-C(70) bisadduct, trimetallic nitride endohedral fullerenes and other C(60) derivatives with multi side chains. The synthesis and physicochemical properties of PC(60)BM and PC(70)BM were also introduced considering the importance of the two fullerene acceptors.     

Thermal behavior of J-aggregates in mixed Langmuir-Blodgett films composed of merocyanine dye and deuterated arachidic acid investigated by UV-visible and infrared absorption spectroscopy

We have investigated the thermal behavior of J-aggregates in the mixed Langmuir-Blodgett (LB) films composed of the merocyanine dye (MS18)-deuterated arachidic acid (C20-d) binary system in the temperature range from 25 to 250 degrees C by means of UV-visible and IR transmission absorption spectroscopy. The temperature-dependent variations in both UV-visible and IR absorption spectra indicate that the MS18 aggregation states are linked with the MS18 intramolecular charge transfer and the behavior of the packing, orientation, conformation, and thermal mobility of the MS18 hydrocarbon chain. The J-aggregate formed at 25 degrees C in the mixed LB films dissociates in the temperature range from 25 to 110 degrees C, which is mainly ascribed to the increase in the thermal mobility of MS18 hydrocarbon chain and the dissociation of the chelation by a cadmium ion to the MS18 keto group. A thermally induced blue-shifted band appears at around 515 nm from 110 to 160 degrees C. This band is attributed to oligomeric aggregation with side-by-side alignment of the MS18 transition dipole moments on the basis of the shift to a higher-energy side, broadening, and temporary increment of the MS18 intramolecular charge transfer of the band. Consequently, the appearance of the thermally induced blue-shifted band indicates the possibility that the MS18 aggregation states can be controlled from the red shift to the blue shift by the annealing method adopted in the present study.     

Rare solvent annealing effective benzo(1,2-b:4,5-b')dithiophene-based low band-gap polymer for bulk heterojunction organic photovoltaics

A newly synthesized benzo(1,2-b:4,5-b')dithiophene-based low band-gap copolymer pBCN is amenable to solvent annealing in the fabrication of organic photovoltaics, of which power conversion efficiency is greatly improved to 4.2% with PC(61)BM or 4.9% with PC(71)BM.     

Impact of environmentally friendly processing solvents on the properties of blade‐coated polymer solar cells

High‐performance polymer solar cells (PSCs) are typically fabricated by spin coating in inert atmosphere from toxic halogenated solvents such as 1,2‐dichlorobenzene (o‐DCB) and chlorobenzene. This fabrication process is potentially hazardous for both the humans and the environment and dramatically impacts the possibility for the organic photovoltaic technology to be adopted at large scale. In this work, efficient PSCs blade coated in air using nonhalogenated 1,2,4‐trimethylbenzene (TMB) as processing solvent are demonstrated. The active layer, based on a previously synthesized benchmark polymer PFQ2T‐benzodithiophene blended with [6,6]‐phenyl‐C61‐butyric acid methyl ester (PC₆₁BM), showed an enhanced solid‐state aggregation induced by the use of TMB. Compared to o‐DCB‐processed devices, the solar cells fabricated from TMB resulted 10% more efficient with a power conversion efficiency of 4.20%. Interestingly, the improved photovoltaic performance resulted from the combination of synergic effects promoted by a more favorable film morphology, such as high exciton dissociation efficiency and lower bimolecular recombinations resulting in higher charge collection efficiency at the electrodes. The positive effect of TMB, compared to that of commonly employed halogenated solvents, confirms the great potential of this approach for the development of efficient PSCs for practical applications with reduced environmental impact. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 487–494     

Facile synthesis of a 56π-electron 1,2-dihydromethano-[60]PCBM and its application for thermally stable polymer solar cells

A facile synthesis was employed to make a 56π-electron methano-PC(61)BM with a very small 1,2-dihydromethano (CH(2)) group. This new fullerene derivative possesses high electron mobility (0.014 cm(2) V(-1) s(-1)) and higher LUMO energy level (0.15 eV) than PC(61)BM. Bulk hetero-junction devices based on using poly(3-hexylthiophene) and methano-PC(61)BM as active layer exhibited better performance and thermal stability than those using the PC(61)BM analogue.     

Dihydronaphthyl-based [60]fullerene bisadducts for efficient and stable polymer solar cells

Dihydronaphthyl-based [60]fullerene bisadduct derivative, NC(60)BA, was synthesized at mild temperature in high yield. NC(60)BA not only possesses a LUMO energy level 0.16 eV higher than PC(61)BM but also has amorphous nature that can overcome thermal-driven crystallization. The fabricated P3HT:NC(60)BA-based polymer solar cells exhibit superior photovoltaic performance and thermal stability compared to PC(61)BM-based devices under the same conditions.     

低聚合度的交替共聚物太阳能电池的形态和性能

制备了由低聚合度的聚[2,6-(4,4-双-(2-乙基己基)-4H-环戊[2,1-b;3,4-b']双噻吩)-交替-4,7-(2,1,3-苯并噻二唑)](LDP-PCPDTBT)、[6,6]-苯基-C61-丁酸甲酯(PC61BM)和聚甲基丙烯酸甲酯(PMMA)组成的三组分共混薄膜,并通过加入溶剂添加剂(1,8-二溴辛烷,DBO)对体系进行了优化处理.研究发现,没有加入DBO时,LDP-PCPDTBT和PC61BM相在PMMA的基质中分别是无定形的和结晶的;加入DBO后,PMMA基质中LDP-PCPDTBT和PC61BM间的相分离过程得到优化,有机太阳能电池的能量转换效率相应提高了32.4%.     

An acrylated fullerene derivative for efficient and thermally stable polymer solar cells

The continuous microstructure evolution occurring in active layers of polymer-fullerene solar cells is one of the main causes for their device instability. With aim to tackle it, this work developed a new polymerizable fullerene acceptor, [6,6]-phenyl-C₆₁-butyl acrylate (PC₆₁BA). It was found that PC₆₁BA has similar light-absorption properties and HOMO and LUMO energy levels as [6,6]-phenyl-C₆₁-butyric acid methyl ester (PC₆₁BM), and can be converted into insoluble oligomers upon heating at 150 °C. Polymer-fullerene solar cells using poly(3-hexylthiophene) (P3HT) as donor and PC₆₁BA as acceptor exhibited an optimized efficiency of 3.54%, the performance comparable to P3HT/PC₆₁BM cells (optimized efficiency: 3.70%). But, the former possess much better thermal stability than the latter owing to aggregation suppression by the polymerized PC₆₁BA. These results indicate that PC₆₁BA, unlike most previous reported, is a unique polymerizable fullerene derivative that can be used alone as acceptor to achieve both efficient and thermally stable polymer solar cells.     

Fluorobenzotriazole-Based Medium-Bandgap Conjugated D–A Copolymers for Applications to Fullerene-Based and Nonfullerene Polymer Solar Cells

Two new medium-bandgap (MBG) donor–acceptor (D–A) conjugated polymers (PSTF and PDTS) with fluorobenzotriazole as an A unit and spiro[cyclopenta[1,2-b:5,4-b′]dithiophene-4,9′-fluorene] (STF) or dithienosilole (DTS) as the D unit are designed and synthesized as donor materials for polymer solar cell (PSC) applications. PSTF shows a broader absorption spectrum relative to PDTS reflecting an additional high-energy absorption band due to the conjugated thiophene side chains on STF moiety. Compared with PDTS, PSTF exhibits weaker π–π aggregation and lower lying HOMO level. Photovoltaic properties of the PSCs reveal that either PSTF or PDTS using PC₆₁BM as acceptor exhibits better performances than that of ITIC as acceptor, which results from the simultaneously increased V_oc, J_sc, and FF of PC₆₁BM-based PSCs. Moreover, when combined with PC₆₁BM and ITIC, the PSTF-based PSCs exhibit an efficiency of 3.66% and 2.42%, respectively, which is 45% and almost 1.5 times higher than that of the PDTS-based PSCs, respectively. This can be ascribed to the obviously improved V_oc and FF of PSTF-based PSCs benefitted from the deeper HOMO level and better active layer morphology. Our work demonstrates that using spiro-annulated building block as donor unit to construct MBG D-A copolymers is an alternative and effective approach for achieving efficient donor materials in PSCs. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2330–2343