低成本低聚合度结晶共聚物基太阳能电池

研究了一种由低聚合度的聚[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)、聚甲基丙烯酸甲酯(PMMA)和[6,6]-苯基-C61-丁酸甲酯(PC61BM)组成的三组分共混薄膜。通过加入溶剂添加剂1,8-二溴辛烷(DBO)进行处理,在未加入溶剂添加剂时,LDP-PCPDTBT相和PC61BM相在PMMA的基质中分别处于无定形和结晶态;应用DBO促进了LDP-PCPDTBT成分的结晶和PC61BM成分的聚集,开路电压明显提高,PMMA基质中的LDP-PCPDTBT和PC61BM的相分离尺度优化,太阳能电池的能量转换效率提高近50%。研究表明,低聚合度交替共聚物能够作为有效的给体材料,与PMMA联合使用利于降低有机太阳能电池材料的成本。     

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(3-己基噻吩)作为光谱增感层在有机太阳电池光谱响应增强中的应用

报道了利用聚(3-己基噻吩)(P3HT)作为前置缓冲层来弥补(4,8-双-(2-乙基己氧基)-苯并[1,2-b:4,5-b']二噻吩)-(4-氟代噻并[3,4-b]噻吩(PBDT-TT-F):[6,6]-苯基-C₆₁-丁酸甲酯(PC₆₁BM)共混体相异质结(BHJ)电池对450-600 nm处光谱响应不足的新的器件结构设计思路. 光谱带隙为1.8 eV的PBDT-TT-F 在550-700 nm处有很强的光谱吸收, 在有机太阳电池器件上有很好的应用潜能. 但其在350-550 nm处的吸收不强, 影响了器件对太阳光谱的利用效率. 与此相比, P3HT薄膜的光谱吸收主要在450-600 nm范围内, 同PBDT-TT-F 形成良好的互补关系. 新设计的器件外量子效率(EQE)研究结果表明, 利用P3HT 作为前置缓冲层可以与PBDT-TT-F:PC₆₁BM薄膜中的PC₆₁BM形成平面异质结, 从而拓展了器件在450-600 nm处的光谱响应范围,实现光谱增感作用. 优化P3HT的厚度为20 nm左右, 器件对外输出的短路光电流密度从11.42 mA·cm^-2提高到12.15 mA·cm^-2, 达到了6.3%的提升.     

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.     

聚合物:富勒烯薄膜光伏电池的反常高温热稳定性研究

聚合物太阳能电池光电转换效率已接近商业化要求,但稳定性差却成为其实用化瓶颈因素.高温暴晒是聚合物太阳能电池实用化必须面临的环境,因此提高聚合物太阳能电池的热稳定性至关重要.本文以典型的Poly(3-hexylthiophene-2,5-diyl(P3HT):[6,6]-Phenyl-C61-butyric acid methyl ester(PC61BM)基聚合物太阳能电池为研究模型,考察其在不同加热温度下(50~110℃)持续工作时的器件效率变化行为,结果发现电池在高温下表现出一种非常规的性能衰减再回升的行为,具体表现为高温下电池首先表现指数式急速衰减(20%~25%),随后发生反常的性能快速恢复至接近初始效率,之后电池保持超长的高温稳定性.光学显微镜和激光光束诱导电流成像结果证明,顶电极覆盖可以有效抑制活性层中PC61BM的聚集结晶,因而电池的反常热诱导稳定性提升与PC61BM的大量聚集结晶无关.活性层薄膜的紫外可见吸收光谱和器件外量子效率的表征结果证明,持续高温加热没有促进PC61BM二聚体的形成,反而有利于PC61BM二聚体的解离.综合实验分析结果,推测PC61BM在光照下的快速二聚反应及其高温解离是导致电池表现出反常热稳定性提升行为的主要原因.实验结果揭示了初期制备的聚合物太阳能电池实际处于一种亚稳态,对器件进行短暂的前期热退火有利于稳定活性层结构,消除亚稳态,有效提升器件稳定性.本研究工作不仅对富勒烯基聚合物太阳能电池的热诱导反常稳定性提升机理机制给出了解释,而且提供了一种提高聚合物太阳能电池稳定性的新策略.     

新型酞菁-苝分子异质结的合成及其光伏性能研究

通过酰胺键将酞菁(电子给体单元)和苝二酰亚胺(电子受体单元)偶联,合成了新型的酞菁-苝分子异质结,其在二氯甲烷、氯仿、四氢呋喃等常用溶剂中有较好的溶解度.紫外光谱分析表明其吸收光谱是酞菁和苝二酰亚胺信号的叠加,出现在300～780 nm之间.该分子摩尔消光系数高达105L mol-1 cm-1数量级,说明具有较宽的太阳光谱覆盖范围和很高的吸光系数.基于这些良好的光谱响应特性,制备了以该分子与[6,6]-苯基-C61-丁酸酸甲酯(PC61BM)为光活性层的有机太阳能电池(OSCs),该电池器件结构为ITO/聚(3,4-乙撑二氧噻吩):聚苯乙烯磺酸(PEDOT:PSS)/酞菁-苝给受体分子:PC61BM/Ca/Al,光电转换效率(PCE)为0.009%,对应的开路电压(Voc)为0.472 V,短路电流(Jsc)为0.104 mA/cm2,填充因子(FF)为0.18.     

侧链含不饱和基团取代的硫代双烯型镍络合物的合成及其性能

合成了3个侧链含不饱和基团取代的硫代双烯型镍络合物,即双[4,5-二(4'-叔丁基苄基)硫-1,3-二硫杂环戊烯]镍(2a)、双[4,5-二(烯丙基)硫-1,3-二硫杂环戊烯]镍(2b)和双[4,5-二(3'-苯基-烯丙基)硫-1,3-二硫杂环戊烯]镍(2c)以及作为参照品的一个侧链含饱和基团的硫代双烯型镍络合物,即双[4,5-二(癸基)硫-1,3-二硫杂环戊烯]镍(2d).它们的结构经1H NMR和质谱得到了表征.这些化合物在甲苯中有较好的溶解性,最大吸收波长(λmax)在1000 nm左右,而且取代基对它们最大吸收波长的位移影响很小.它们在固态聚甲基丙烯酸甲酯(PMMA)中的λmax也在1000 nm左右,且浓度较低时,吸收曲线未见有宽化的迹象.固态循环伏安的测试结果表明,苯基的引入对提高这类化合物的氧化电位有影响.热重分析(TGA)的结果表明,这类化合物失重5%的温度都在200℃以上.氙灯(300 W)照射100 min,它们的吸光度在甲苯中下降不到10%,在固态的PMMA中下降不到2%,苯基的引入有助于提高这类化合物在溶液和固态PMMA中的光化学稳定性.     

第三组分端基对非富勒烯有机太阳能电池性能的影响

<正>有机聚合物太阳能电池具有成本低、重量轻、半透明、制作工艺简单、可制备大面积柔性器件等突出优点,成为近年来的研究热点之一~1。有机太阳能电池活性层由电子给体和电子受体组成,通常采用本体异质结结构~2。富勒烯电子受体及其衍生物如[6,6]-苯基-C_(61)-丁酸甲酯(PC_(61)BM)和[6,6]-苯基-C_(71)-丁酸甲酯(PC_(71)BM)具有电子迁移     

无规聚甲基丙烯酸甲酯在聚乙二醇齐聚物溶液中的自组织及凝胶行为

高度立构规整的聚甲基丙烯酸甲酯在许多有机溶剂中都有形成热可逆凝胶的倾向[1] .高间规度的聚甲基丙烯酸甲酯 ( s PMMA)在溶液及凝胶中的自组织行为可以通过核磁共振、光散射、小角中子散射及红外光谱来研究 [2～ 5] .在甲苯、邻二甲苯和邻二氯苯等溶剂中 ,s PMMA链中的大部分单元都处于有序状态 ;而在苯和氯仿等溶剂中 ,没有这种有序结构形成 ,分子链处于无规线团状态 [5,6] .一般认为 ,这种有序结构的形成与分子链中一定长度间规序列结构单元的存在有关 [7] .对于无规聚甲基丙烯酸甲酯 ( a PMMA) ,由于其较低的间规度 ( <66% ) ,在…     

新型基于二氟苯并噻二唑和双噻吩丙烯腈共轭聚合物的设计、合成及光伏性能

设计并合成了两种基于5,6-二氟苯并噻二唑和双噻吩丙烯腈单元的D-A型共轭聚合物,聚[(5,6-二氟-苯[c][1,2,5]噻二唑-4,7-基)-交替-((E)-2,3-双(3'-(2-辛基十二烷基)-(2,2'-双噻吩)-5,5'-基)丙烯腈)](DFBT812)和聚[(5,6-二氟-苯[c][1,2,5]噻二唑-4,7-基)-交替-((E)-2,3-双(3'-(2-癸基十四烷基)-(2,2'-双噻吩)-5,5'-基)丙烯腈)](DFBT1014)作为聚合物太阳电池的给体材料。通过侧链工程,引入了2-辛基十二烷基和2-癸基十四烷基侧链实现对聚合物的溶解性,结晶性以及共混膜形貌的调节。研究结果表明,共轭聚合物DFBT812与PC_(61)BM的共混膜表现出更好的相分离尺度,能够促进载流子的传输和抽取。基于共轭聚合物DFBT812的太阳电池器件取得了0.87 V的开路电压和6.25%的能量转换效率。除此之外,基于DFBT812的聚合物太阳电池器件在活性层厚度为220 nm时仍然表现出6%的能量转换效率。     

Efficient P3HT:PC61BM solar cells employing 1,2,4-trichlorobenzene as the processing additives

The efficiency of the poly(3-hexylthiophene)(P3HT) and [6,6]-phenyl C_(61)-butyric acid methyl ester(PC_(61)BM) based organic solar cells was enhanced by using 1,2,4-trichlorobenzene(TCB) as a processing additive to control the blend morphology. The addition of TCB improved the arrangement of P3HT which resulted in good phase separated blend films. Correspondingly, the optimized solar cells showed a power conversion efficiency(PCE) of 4.17% with a fill factor(FF) of 0.69, which were higher than those of common thermal annealing devices(PCE 3.84%, FF 0.67). The efficiency was further improved to 4.74% by thermal annealing at 150 °C for 10 min with a higher FF of 0.74.     

Thieno[3,2-b]thiophene-diketopyrrolopyrrole-containing polymers for high-performance organic field-effect transistors and organic photovoltaic devices

We report the synthesis and polymerization of a novel thieno[3,2-b]thiophene-diketopyrrolopyrrole-based monomer. Copolymerization with thiophene afforded a polymer with a maximum hole mobility of 1.95 cm(2) V(-1) s(-1), which is the highest mobility from a polymer-based OFET reported to date. Bulk-heterojunction solar cells comprising this polymer and PC(71)BM gave a power conversion efficiency of 5.4%.     

Tetrathienoanthracene-based copolymers for efficient solar cells

A series of semiconducting copolymers (PTAT-x) containing extended π-conjugated tetrathienoanthracene units have been synthesized. It was shown that the extended conjugation system enhanced the π-π stacking in the polymer/PC(61)BM blend films and facilitated the charge transport in heterojunction solar cell devices. After structural fine-tuning, the polymer with bulky 2-butyloctyl side chains (PTAT-3) exhibited a PCE of 5.6% when it was blended with PC(61)BM.     

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.     

Effects of additives on the morphology of solution phase aggregates formed by active layer components of high-efficiency organic solar cells

Processing additives are used in organic photovoltaic systems to optimize the active layer film morphology. However, the actual mechanism is not well understood. Using X-ray scattering techniques, we analyze the effects of an additive diiodooctane (DIO) on the aggregation of a high-efficiency donor polymer PTB7 and an acceptor molecule PC(71)BM under solar cell processing conditions. We conclude that DIO selectively dissolves PC(71)BM aggregates, allowing their intercalation into PTB7 domains, thereby optimizing both the domain size and the PTB7-PC(71)BM interface.     

A naphthodithiophene-diketopyrrolopyrrole donor molecule for efficient solution-processed solar cells

We report the synthesis, characterization, and first implementation of a naphtho[2,3-b:6,7-b']dithiophene (NDT)-based donor molecule in highly efficient organic photovoltaics (OPVs). When NDT(TDPP)(2) (TDPP = thiophene-capped diketopyrrolopyrrole) is combined with the electron acceptor PC(61)BM, a power conversion efficiency (PCE) of 4.06 ± 0.06% is achieved-a record for a PC(61)BM-based small-molecule OPV. The substantial PCE is attributed to the broad, high oscillator strength visible absorption, the ordered molecular packing, and an exceptional hole mobility of NDT(TDPP)(2).     

Structural tuning of low band gap intermolecular push/pull side-chain polymers for organic photovoltaic applications

A series of novel low band gap donor-acceptor (D-A) type organic co-polymers (BT-F-TPA,BT-CZ-TPA and BT-SI-TPA) consisting of electron-deficient acceptor blocks both in main chains (M1) and at the pendant (M2) were polymerized with different electron rich donor (M3-M5) blocks,i.e.,9,9-dihexyl-9H-fluorene,N-alkyl-2,7-carbazole,and 2,6-dithinosilole,respectively,via Suzuki method.These polymers exhibited relatively low band gaps (1.65-1.88 eV) and broad absorption ranges (680-740 nm).Bulk heterojunction (BHJ) solar cells incorporating these polymers as electron donors,blended with [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) or [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as electron-acceptors in different weight ratios were fabricated and tested under 100 mW/cm2 of AM 1.5 with white-light illumination.The photovoltaic device containing donor BT-SI-TPA and acceptor PC71BM in 1:2 weight ratio showed the best power conversion efficiency (PCE) value of 1.88％,with open circuit voltage (Voc) =0.75 V,short circuit current density (Jsc) =7.60 mA/cm2,and fill factor (FF) =33.0％.