取代基结构对聚[(3-烷基)噻吩-2,5]-取代苯甲烯衍生物三阶非线性光学性能的影响

采用3-烷基噻吩与对硝基苯甲醛和对二甲氨基苯甲醛的聚合反应得到了5种聚(3-烷基)噻吩取代苯甲烯衍生物:聚(3-丁基)噻吩对硝基苯甲烯(PBTNBQ)、聚(3-己基)噻吩对硝基苯甲烯(PHTNBQ)、聚(3-丁基)噻吩对二甲氨基苯甲烯(PBTDMABQ)、聚(3-己基)噻吩对二甲氨基苯甲烯(PHTDMABQ)和聚(3-辛基)噻吩对二甲氨基苯甲烯(POTDMABQ).计算其光学禁带宽度分别为PBTNBQ(1.82eV),PHTNBQ(1.85eV),PBTDMABQ(1.71eV),PHTDMABQ(1.78eV)和POTDMABQ(1.67eV).利用简并四波混频技术测量了5种聚合物薄膜的三阶非线性极化率,分别为1.74×10^-8,1.82×10^-8,5.62×10^-9,8.64×10^-9和1.22×10^-8esu,均具有较大的三阶非线性光学性能.针对取代基结构对聚(3-烷基)噻吩取代苯甲烯衍生物的三阶非线性光学性能的影响从分子内极化程度和主链电子的离域程度两个方面进行了讨论.     

Synthesis and photovoltaic properties of fluorene-based copolymers with narrow band-gap units on the side chain

A series of novel polyfluorene copolymers are developed by covalently attaching narrow band gap aryl-heterocycle units of Th-BT-TPA to the side chain of polyfluorene with an alkyl phenyl spacer through Pd-catalyzed Suzuki coupling reactions. The resulting copolymers are soluble in common organic solvents. The electrochemical, optical, and photovoltaic properties of the copolymers are studied. Electrochemical and optical analysis reveal that these polymers exhibit relatively low band gaps from 1.95 to 2.00 eV and exhibit strong absorption in the 300-620 nm region. BHJ solar cells blending copolymers PF-MR15-DBT35 with [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) (1:1 weight ratio) as the active layer present a high open-circuit voltage (V_oc∼1.0 V) and a power conversion efficiency of 0.7% under simulated solar light AM1.5G (80 mW/cm²). Further investigations of other polyfluorene copolymers with narrow band gap aryl-heterocycle units on the side chain are in progress.     

一种新型低带隙共轭聚合物的合成及其光学性质

在钯催化剂作用下, 通过4,7-二(5-溴-2-噻吩基)[2,1,3]苯并噻二唑与2,5-二乙炔基-3-辛基噻吩的偶联反应, 合成了一种新的共轭高分子聚4,7-二(2-噻吩基)苯并噻二唑-3-辛基噻吩二炔(PTE-DTBT). 通过紫外可见吸收光谱及荧光光谱对其光学性质进行了研究. 紫外-可见吸收谱结果表明, PTE-DTBT的固体膜光学带隙为1.71 eV; 电化学测试其带隙为1.88 eV. TiO₂/PTE-DTBT共混固体膜的荧光发射谱结果表明电子供体PTE-DTBT分子与电子受体TiO₂分子间存在有效的电子转移.     

高分子光伏材料聚对苯乙烯撑-喹喔啉共聚物的合成与光学性能研究

高分子光伏材料聚对苯撑乙烯撑(PPV)由于低廉的价格, 容易加工的性能与可调的光学性能, 有可能成为新一代太阳能材料. 然而PPV较宽的带隙阻碍了PPV太阳能电池效率进一步提高. 合成了一种较低带隙的新型高分子光伏材料 PPV-PQ. 用NMR, FT-IR, 元素分析, GPC和TGA与循环伏安法对PPV-PQ进行了结构表征与性能检测, 并对它在氯仿溶液与固态薄膜下的紫外-可见吸收与荧光发射光谱进行了研究. 结果显示, 由于在固态下存在较强的分子间作用, 分子链的共平面性增加, 所以PPV-PQ无论是紫外-可见吸收, 还是荧光发射光谱, 在固态薄膜下都比在氯仿溶液里发生明显红移. 即使在浓溶液中, 分子链间也存在较强的作用力, 使得PPV-PQ荧光发射峰随溶液浓度的增加而发生红移. 紫外-可见光谱显示, PPV-PQ由于大体积的吸电子单元引起了较大的空间位阻, 最大吸收峰比PPV稍微蓝移, 但吸收却比PPV向长波延展, 带隙比PPV低, 只有1.92 eV. 循环伏安法结果表明PPV-PQ与PCBM两者的LUMO之间有足够的能量差异, 加上PPV-PQ与富勒烯衍生物C117共混物薄膜发生荧光猝灭, 都说明PPV-PQ上光激发电子能够转移到富勒烯衍生物上. 因此, PPV-PQ可以用作高分子光伏材料.     

用CdSe/ZnS量子点提高体异质结有机太阳电池的效率

通过掺杂吸收光谱在可见光波段的量子点可提高聚合物对可见光的吸收,因此掺杂CdSe/ZnS核-壳结构量子点(CQDs)能提高聚(3-己基噻吩):[6,6]-苯基-C61-丁酸甲酯(P3HT:PCBM)体异质结太阳电池的能量转换效率.本文研究了CdSe/ZnS量子点在P3HT:PCBM中的不同掺杂比例及其表面配体对太阳电池光伏性能的影响,优化器件ITO(氧化铟锡)/PEDOT:PSS(聚(3,4-乙撑二氧噻吩:聚苯乙烯磺酸)/P3HT:PCBM:(CdSe/ZnS)/Al的能量转换效率达到了3.99%,与相同条件下没有掺杂量子点的参考器件ITO/PEDOT:PSS/P3HT:PCBM/Al相比,其能量转换效率提高了45.1%.     

Fabrication of Dye-sensitized Solar Cells and Fluorescence Quenching Study Using Thiophene Based Copolymers

Photovoltaic performance of dye sensitized solar cells fabricated with a commercially available thiophene based copolymer was investigated. Poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(bithiophene)], a highly soluble polythiophene, was used as a sensitizer. An open-circuit voltage of 0.64 V and a short-circuit current density of 0.36 mA/cm² were measured. The incident photon to current conversion efficiency for the polymer was measured. Fluorescence from the other polythiophene, poly(3,3′-didodecyl quarter thiophene) was found to be quenched when blended with phenyl C₆₁ butyric acid methyl ester (PCBM) (1:1 wt ratio), indicating the charge transfer from the conjugated polymer to PCBM.     

窄能隙共轭聚合物:聚[(3-烷基)噻吩-2,5]-取代苯甲烯衍生物的合成与表征

合成了3-丁基噻吩和3-辛基噻吩,并分别与对硝基苯甲醛和对二甲氨基苯甲醛进行聚合反应得到了具有极低能隙的聚(3-丁基噻吩)对硝基苯甲烯(PBTNBQ)、聚(3-丁基噻吩)对二甲氨基苯甲烯(PBTDMABQ)和聚(3-辛基噻吩)对二甲氨基苯甲烯(POTDMABQ).采用红外光谱、核磁共振氢谱和紫外-可见吸收光谱确认了产物的结构,发现中间产物聚(3-烷基)噻吩取代苯甲烷衍生物中存在部分醌化产物.根据E_g与入射光子能量hν的关系,采用2种模型计算了3种聚合物薄膜的光学禁带宽度为PBTNBQ1.63,1.84eV;PBTDMABQ1.44,1.75eV和POTDMABQ1.32,1.69eV,属窄能隙共轭聚合物.     

Examining the effect of the dipole moment on charge separation in donor-acceptor polymers for organic photovoltaic applications

A new low band gap copolymer PBB3 containing [6,6']bi[thieno[3,4-b]thiophenyl]-2,2'-dicarboxylic acid bis-(2-butyloctyl) ester (BTT) and 4,8-bis(2-butyloctyl)benzo[1,2-b:4,5-b']dithiophene (BDT) units was synthesized and tested for solar cell efficiency. PBB3 showed a broad absorbance in the near-IR region with a substantially red-shifted (by more than 100 nm) λ(max) at 790 nm as compared to the PTB series of polymers, which have been previously reported. The PBB3 polymer also showed both a favorable energy level match with PCBM (with a LUMO energy level of -3.29 eV) and a favorable film domain morphology as evidenced by TEM images. Despite these seemingly optimal parameters, a bulk heterojunction (BHJ) photovoltaic device fabricated from a blend of PBB3 and PC(71)BM showed an overall power conversion efficiency (PCE) of only 2.04% under AM 1.5G/100 mW cm(-2). The transient absorption spectra of PBB3 showed the absence of cationic and pseudo charge transfer states that were observed previously in the PTB series polymers, which were also composed of alternating thienothiophene (TT) and BDT units. We compared the spectral features and electronic density distribution of PBB3 with those of PTB2, PTB7, and PTBF2. While PTB2 and PTB7 have substantial charge transfer characteristics and also relatively large local internal dipoles through BDT to TT moieties, PTBF2 and PBB3 have minimized internal dipole moments due to the presence of two adjacent TT units (or two opposing fluorine atoms in PTBF2) with opposite orientations or internal dipoles. PBB3 showed a long-lived excitonic state and the slowest electron transfer dynamics of the series of polymers, as well as the fastest recombination rate of the charge-separated (CS) species, indicating that electrons and holes are more tightly bound in these species. Consequently, substantially lower degrees of charge separation were observed in both PBB3 and PTBF2. These results show that not only the energetics but also the internal dipole moment along the polymer chain may be critical in maintaining the pseudocharge transfer characteristics of these systems, which were shown to be partially responsible for the high PCE device made from the PTB series of low band gap copolymers.     

Effects of Block Length in Copolymers Based on Regioregular Oligothiophenes Linked With Electron‐Accepting Units

Copolymers with an alternating structure of regioregular oligo(3‐hexylthiophene) (O3HT) with different lengths and 2,5‐dibutyl‐3,6‐di(thiophen‐2‐yl)pyrrolo[3,4‐c]pyrrole‐1,4(2H,5H)‐dione (DPP) were synthesized through Stille coupling reaction. The light absorption of the copolymers can be rationally tuned to have a broad spectrum across the visible region by adjusting the length of O3HT. Organic solar cells fabricated with the copolymers and PCBM showed a broad photoresponse and a comparable efficiency to that of poly(3‐hexylthiophene) (P3HT):PCBM cells. The external quantum efficiency and fluorescence spectra suggested that the intrachain energy transfer from the O3HT block to the vicinity of the DPP unit could limit the photovoltaic performance of the copolymers.     

Synthesis of Poly[（3-octanoylpyrrole-2,5-diyl）-p-nitrobenzylidene] and Its Third-order Nonlinear Optical Property

Introduction Nonlinearoptical(NLO)organicpolymers havereceivedincreasingattentionbecauseoftheir excellentbehaviorandgoodprospectsforapplica- tiontohightechnologiessuchasopticalcommuni- cation,highdensityopticalstorageandall-optical informationprocess[1_4].Thepoly[heteroarylene- methines]andtheirderivativesareregardedaspo- tentiallyapplicativeNLOmaterials[5_8],buttheir solubilityandfilm-formingperformancearenot goodwhichisabottleneckproblemfortheapplica- tionofthesepolymers.Inthisstudy,anovel…     

New conjugated copolymers based on benzo[1,2‐b; 3,4‐b′]dithiophene and derivatives of benzo[g]quinoxaline for bulk heterojunction solar cells

A series of new low‐band gap copolymers based on dioctyloxybenzo[1,2‐b;3,4‐b′] dithiophene and bis(2‐thienyl)‐2,3‐diphenylbenzo[g]quinoxaline monomers have been synthesized via a Stille reaction. The effect of different functional groups attached to bis(2‐thienyl)‐2,3‐diphenylbenzo[g]quinoxaline was investigated and compared with their optical, electrochemical, hole mobility, and photovoltaic properties. Polymer solar cell (PSC) devices of the copolymers were fabricated with a configuration of ITO/ PEDOT: PSS/copolymers: PCBM (1:4 wt ratio)/Ca/Al. The best performance of the PSC device was obtained by using PbttpmobQ as the active layer. A power conversion efficiency of 1.42% with an open‐circuit voltage of 0.8 V, a short‐circuit current (JSC) of 5.73 mA cm⁻², and a fill factor of 30.9% was achieved under the illumination of AM 1.5, 100 mW cm⁻². © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Fluorine substituted conjugated polymer of medium band gap yields 7% efficiency in polymer-fullerene solar cells

Recent research advances on conjugated polymers for photovoltaic devices have focused on creating low band gap materials, but a suitable band gap is only one of many performance criteria required for a successful conjugated polymer. This work focuses on the design of two medium band gap (~2.0 eV) copolymers for use in photovoltaic cells which are designed to possess a high hole mobility and low highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels. The resulting fluorinated polymer PBnDT-FTAZ exhibits efficiencies above 7% when blended with [6,6]-phenyl C(61)-butyric acid methyl ester in a typical bulk heterojunction, and efficiencies above 6% are still maintained at an active layer thicknesses of 1 μm. PBnDT-FTAZ outperforms poly(3-hexylthiophene), the current medium band gap polymer of choice, and thus is a viable candidate for use in highly efficient tandem cells. PBnDT-FTAZ also highlights other performance criteria which contribute to high photovoltaic efficiency, besides a low band gap.     

Tetra-EDOT substituted 3D electrochromic polymers with lower band gaps

A couple of novel electrochromic materials poly(2,3,4,5-tetrakis(2,3-hydrothieno[3,4-b]dixin-5-yl)-1-methyl-1H-pyrrole)(P(t-EDOT-mPy))and poly(5,5',5",5'"-(thiophene-2,3,4,5-tetrayl)tetrakis(2,3-dihydrothieno[3,4-b][1,4]dioxine))(P(t-EDOTTh))are electrodeposited via multi-position polymerization of their tetra-EDOT substituted monomers t-EDOT-mPy and t-EDOT-Th,respectively.Compared with the linear 2D structured poly(thiophene)(E_g=2.2 eV)and poly(2,5-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)thiophene)(E_g=1.7eV),P(t-EDOT-Th)(E_g=1.62eV)has the lowest band gap.Hence,we speculate that the band gaps of the two polymers,having 3D structures,are decreased in contrast to non-substituted polymers or bi-EDOT substituted polymers,thiophene and 1-methyl-1H-pyrrole.The results indicated that P(t-EDOT-Th)thin films are more stable and show higher transmittance amid two polymers,which may find their utilization in organic optoelectronics.     

Synthesis and electroluminescent properties of soluble poly(3,6-fluorene) and its copolymer

Soluble poly(3,6-fluorene) and its copolymer were synthesized by nickel-catalyzed coupling. Poly(3,6-fluorene) exhibited the optical band gap of 3.6 eV, the emission maximum at 347 nm, and the HOMO level of -6.05 eV. These results confirm that 3,6-linkage is an effective way to get wide band gap conjugated polymers. Furthermore, its copolymer containing triarylamine moieties emits deep-blue light, which means that the adjustable blue light emission can be obtained from their copolymers via energy transfer.     

Role of balanced charge carrier transport in low band gap polymer:Fullerene bulk heterojunction solar cells

Lowering of the optical band gap of conjugated polymers in bulk heterojunction solar cells not only leads to an increased absorption but also to an increase of the optimal active layer thickness due to interference effects at longer wavelengths. The increased carrier densities due to the enhanced absorption and thicker active layers make low band gap solar cells more sensitive to formation of space charges and recombination. By systematically red shifting the optical parameters of poly[2‐methoxy‐5‐(3′,7′‐dimethyloctyloxy)‐p‐phenylenevinylene] and 6,6‐phenyl C₆₁‐butyric acid methyl ester, we simulate the effect of a reduced band gap on the solar cell efficiencies. We show that especially the fill factor of low band gap cells is very sensitive to the balance of the charge transport. For a low band gap cell with an active layer thickness of 250 nm, the fill factor of 50% for balanced transport is reduced to less than 40% by an imbalance of only one order of magnitude. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011     

Synthesis of Poly[（3-octanoylpyrrole-2,5-diyl）-p-（N, N-dimethylamino）benzylidene] and Its Properties by Nitrogen Ion Implantation

Introduction Nonlinearoptical(NLO)organicpolymers havereceivedincreasingattentionbecauseoftheir excellentbehaviorandthegoodprospectsoftheir applicationsinhigh-techareas,suchasoptical communication,high-densityopticalstorageand all-opticalinformationprocess.Poly(pyrrolylme- thine)isanNLOmaterialwithpromisingapplica- tions[1_3].However,itssolubilityandfilm-forming performancearepoor.Inthispaper,anovelsolu- blepoly(pyrrolylmethine),poly[(3-octanoyl-pyr- role-2,5-diyl)-p-(N,N-dimethylamino)ben…     

Soluble narrow band gap and blue propylenedioxythiophene-cyanovinylene polymers as multifunctional materials for photovoltaic and electrochromic applications

A family of soluble narrow band gap donor-acceptor conjugated polymers based on dioxythiophenes and cyanovinylenes is reported. The polymers were synthesized using Knoevenagel polycondensation or Yamamoto coupling polymerizations to yield polymers with molecular weights on the order of 10 000-20 000 g/mol, which possess solubility in common organic solvents. Thin film optical measurements revealed narrow band gaps of 1.5-1.8 eV, which gives the polymers a strong overlap of the solar spectrum. The energetic positions of the band edges were determined by cyclic voltammetry and differential pulse voltammetry and demonstrate that the polymers are both air stable and show a strong propensity for photoinduced charge transfer to fullerene acceptors. Such measurements also suggest that the polymers can be both p- and n-type doped, which is supported by spectroelectrochemical results. These polymers have been investigated as electron donors in photovoltaic devices in combination with PCBM ([6,6]-phenyl C(61)-butyric acid methyl ester) as an electron acceptor based on the near ideal band structures designed into the polymers. Efficiencies as high as 0.2% (AM1.5) with short circuit current densities as high as 1.2-1.3 mA/cm(2) have been observed in polymer/PCBM (1:4 by weight) devices and external quantum efficiencies of more than 10% have been observed at wavelengths longer than 600 nm. The electrochromic properties of the narrow band gap polymers are also of interest as the polymers show three accessible color states changing from an absorptive blue or purple in the neutral state to a transmissive sky-blue or gray in the oxidized and reduced forms. The wide electrochemical range of electrochromic activity coupled with the strong observed changes in transmissivity between oxidation states makes these materials potentially interesting for application to electrochromic displays.     

Donor–acceptor semiconducting polymers based on pyromellitic diimide

Three donor–acceptor copolymers P1 , P2 , and P3 with N,N′‐dodecylpyromellitic diimide as the electron‐acceptor unit with three diethynyl‐substituted donor monomers: 1,4‐diethynyl‐2,5‐bis(octyloxy)benzene, 2,7‐diethynyl‐9,9‐dioctyl‐9H‐fluorene, and 3,3′‐didodecyl‐5,5′‐diethynyl‐2,2′‐bithiophene have been synthesized by Sonogashira crosscoupling polymerization. The synthesized polymers showed deep highest occupied molecular orbital energy levels and larger band gaps (>2.5 eV). Polymers P1 , P2 , and P3 underwent fluorescence quenching with [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM), indicating the intermolecular photo‐induced charge transfer between the donor polymers and the PCBM acceptor. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1617–1622     

Synthesis and characterization of thiazolothiazole‐based polymers and their applications in polymer solar cells

A novel series of thiazolothiazole (Tz)‐based copolymers, poly[9,9‐didecylfluorene‐2,7‐diyl‐alt‐2,5‐bis‐(3‐hexylthiophene‐2‐yl)thiazolo[5,4‐d]thiazole] (P1), poly[9,9‐dioctyldibenzosilole‐2,7‐diyl‐alt‐2,5‐bis‐(3‐hexylthiophene‐2‐yl)thiazolo[5,4‐d]thiazole] (P2), and poly[4,4′‐bis(2‐ethylhexyl)‐dithieno[3,2‐b:2′,3′‐d]silole‐alt‐2,5‐bis‐(3‐hexylthiophene‐2‐yl)thiazolo[5,4‐d]thiazole] (P3), were synthesized for the use as donor materials in polymer solar cells (PSCs). The field‐effect carrier mobilities and the optical, electrochemical, and photovoltaic properties of the copolymers were investigated. The results suggest that the donor units in the copolymers significantly influenced the band gap, electronic energy levels, carrier mobilities, and photovoltaic properties of the copolymers. The band gaps of the copolymers were in the range of 1.80–2.14 eV. Under optimized conditions, the Tz‐based polymers showed power conversion efficiencies (PCEs) for the PSCs in the range of 2.23–2.75% under AM 1.5 illumination (100 mW/cm²). Among the three copolymers, P1, which contained a fluorene donor unit, showed a PCE of 2.75% with a short‐circuit current of 8.12 mA/cm², open circuit voltage of 0.86 V, and a fill factor (FF) of 0.39, under AM 1.5 illumination (100 mW/cm²). © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Ternary Donor–Insulator–Acceptor Systems for Polymer Solar Cells

A series of block copolymers with fixed length of the semiconductor‐block poly(3‐butylthiophene) (P3BT) and varying length of the insulator‐block polystyrene (PS) are synthesized. These copolymers are blended with phenyl‐C61‐butyric acid methyl ester (PCBM) for the bulk heterojunction photoactive layers. With appropriate insulator‐block length and donor–acceptor ratio, the power conversion efficiency increases by one order of magnitude compared with reference devices with pure P3BT/PCBM. PS blocks improve the miscibility of the active layer blends remarkably. The P3BT‐b‐PS crystallizes as nanorods with the P3BT core covered with the PS‐block, which creates a nanoscale tunneling barrier between donor and acceptor leading to more efficient transportation of charge carriers in the semiconductors.