紫外臭氧处理超薄银修饰ITO电极的高效柔性有机太阳能电池

以紫外臭氧处理超薄Ag复合MoO₃或PEDOT：PSS修饰ITO电极的高效柔性有机太阳能电池。通过优化紫外臭氧处理Ag薄膜的时间,提高了以P3HT：PCBM为有源层的器件的功率转换效率,从1.68%（未经过紫外臭氧处理）提高到2.57%（紫外臭氧处理Ag 1 min）。提高的原因推测是紫外臭氧处理形成了AgO_x薄膜,提高了电荷提取并使器件具有高光学透明度、低串联电阻和优异的表面功函数等一些性能。并且,紫外臭氧处理Ag薄膜与MoO₃或者PEDOT：PSS复合修饰ITO的器件效率分别得到提高,Ag薄膜与MoO₃复合修饰ITO的器件效率从2.02%（PET/ITO/MoO₃）提高到2.97%（PET/ITO/AgO_x/MoO₃）,Ag薄膜与PEDOT：PSS复合修饰ITO的器件效率从2.01%（PET/ITO/PEDOT：PSS）提高到2.93%（PET/ITO/AgO_x/PEDOT：PSS）。此外,以PBDTTT-EFT：PC₇₁BM为有源层的柔性聚合物太阳能电池效率可达6.21%。基于ITO的柔性光电器件效率的提高主要归于ITO被Ag/PEDOT：PSS或Ag/MoO₃修饰后功函数的提高。     

Synthesis of benzopyrano[4,3-b](N-arylsulfonyl)indoles and benzopyrano[3,4-b](N-arylsulfonyl)indoles via intramolecular palladium-catalyzed aryl–aryl coupling reaction

A series of benzopyrano[3,4-b](N-arylsulfonyl) indole derivatives and benzopyrano[4,3-b](N-arylsulfonyl) indole derivatives were synthesized from 2- or 3-methylindole via intermolecular S( N )2 reaction and subsequent intramolecular palladium-catalyzed aryl-aryl coupling reaction for the first time. It was suggested that, besides using the Fischer cyclization, benzopyrano[4,3-b]indoles and benzopyrano[3,4-b]indoles could also be prepared via intermolecular S( N )2 reaction and sequential intramolecular palladium-catalyzed coupling reaction.     

Opto-electronic properties of low band gap fused-ring thieno[3,4-b]pyrazine analogues – A theoretical study

The structural, optical and ionic properties of thieno[3,4-b]pyrazine (TP) analogues have been studied using quantum chemical methods. The density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods were employed to optimise the ground- and excited-state geometries of TP analogues. Based on the ground- and excited-state geometries, the absorption and emission spectra have been calculated by using TD-DFT method with 6-311G(d,p) basis set. All the calculations were carried out in gas phase and in acetonitrile and chloroform medium. The solvent-phase calculations were performed using the polarisable continuum model (PCM). It has been observed that the effect of medium on the calculated absorption and emission spectra of these analogues is negligible. The calculated absorption and emission spectra are in good agreement with the available experimental results. This theoretical investigation shows that the fused-ring thieno[3,4-b]pyrazine analogues dibenzo[f,h]thieno[3,4-b]quinoxalines and thieno[3′,4′:5,6]pyrazino[2,3-f][1,10] phenanthroline have lower band gap than the thieno[3,4-b]pyrazine. Hence, these analogues can be used for the production of low band gap conjugated polymers.     

Effect of Specific Solute-Solvent Interaction and Electron Donor-Acceptor Substituents of Novel Pyrazolo Naphthyridines on Fluorescence

Heterocyclic orthoaminoaldehyde such as 4-amino-3-(4-phenyl)-1-phenyl-1H-Pyrazolo[3,4-b]pyridine-5-carbaldehyde was synthesized by multistep reactions involving reduction of azido derivative 2 with LAH to yield aminoalcohol 3 and oxidation of it with MnO(2) to aminoaldehyde 4.The pyridine ring annulated on to 4 by Friedl?nder condensation using acetophenones in presence of base to obtained pyrazolo[3,4-h][1,6]naphthyridine 5 in excellent yield. Study of photophysical properties of 5 revealed that the absorption and emission of them depends up on the substituents present on benzene ring in newly annulated pyridine ring.     

Solution processable reduced graphene oxide decorated ATO electrode for organic solar cells

A novel concept based on the use of solutions containing already qualified crystalline antimony-doped tin oxide SnO₂:Sb (ATO) nanoparticles has been developed. ATO nanoparticles are decorated by reduced graphene oxide (rGO) through a hydrothermal synthesis method. The electrical and optical properties of the graphene oxide films are investigated systematically. The sheet resistance (R _□) of the ATO–rGO films decreases with the increase in the rGO content in the precursor solution. The R _□ can be decreased after the ATO–rGO films annealing in the air for 1 h and can be further decreased by depositing Au on the surface of the films. The optimum property of the ATO–rGO film shows that the R _□ is 80 Ω/□ and the transmittance is about 70 %. The ATO–rGO films are used as the anode of the organic solar cells. The anode film impact on the performance of the devices is studied. Finally, the power conversion efficiency (PCE) of the device based on the poly-(3-hexylthiophene): [6, 6]-phenyl C61-butyric acid methyl ester (PCBM) blended is 1.85 %, and the PCE of the device based on the poly-benzo[1,2-b:4,5-b′] dithio-phene thieno[3,4-b] thiophene:PCBM blended is 3.4 %.     

Effect of an Al-doped ZnO electron transport layer on the efficiency of inverted bulk heterojunction solar cells

Doping is a widely-implemented strategy for enhancing the inherent electrical properties of metal oxide charge transport layers in photovoltaic devices because higher conductivity of electron transport layer (ETL) can increment the photocurrent by reducing the series resistance. To improve the conductivity of ETL, in this study we doped the ZnO layer with aluminum (Al), then investigated the influence of AZO on the performance of inverted bulk heterojunction (BHJ) polymer solar cells based on poly [[4,8-bis [(2-ethylhexyl)oxy]benzo [1,2-b:4,5-b’]dithiophene-2,6-diyl]-[3-fluoro-2[(2-ethylhexyl)-carbonyl]-thieno-[3,4-b]thiophenediyl ]] (PTB7):[6,6]-phenyl C71 butyric acid methyl ester (PC₇₁BM). The measured conductivity of AZO was ~10⁻³ S/cm, which was two orders of magnitude higher than that of intrinsic ZnO (~10⁻⁵ S/cm). By decreasing the series resistance (R_s) in a device with an AZO layer, the short circuit current (J_sc) increased significantly from 15.663 mA/cm² to 17.040 mA/cm². As a result, the device with AZO exhibited an enhanced power conversion efficiency (PCE) of 8.984%.     

不同受体对PTB7聚合物太阳能电池的性能影响的研究

使用两种或者更多种类的富勒烯衍生物作为受体可以使poly(3-己基噻吩)(P3TH)系的混合异质结太阳能电池效率明显提升。这样的提升源于当受体使用富勒烯多重加合物的最低未占轨道(LUMO)提升而使其开路电压升高。虽然其他聚合物也同样能获得高的开路电压,但是大多数的聚合物却不像P3TH一样获得性能提升,在与像苯基-C61-丁酸甲酯 (bis-PCBM)或者the indene-C60 bis-adduct (ICBA)混合后表现出下降的光电流。在此,我们研究这些性能改变的原因。使用[6,6]-苯基C₇₀-丁酸甲酯(PC₇₀BM), ICBA和bis-PC₇₀BM作为受体并且PTB7作为给体,其结构为：ITO/PEDOT：PSS/活性层/LiF/Al,聚合物太阳能电池的表现的性能分别为7.29%, 4.92% 和3.33%。性能的改变可能主要归因于不同受体影响器件激子产生和电荷收集。     

Photoelectric organic nano-thin films prepared from diarylethene

A photoactive nano-film was prepared from a diarylethene derivative, 1,2-bis[6-(3,4-ethylenedioxythienyl)-2-methyl-1-benzothiophen-3-yl]perfluorocyclopentene (BTFTT) and 3,4-ethylenedioxythiophene (EDOT), by electrochemical anodic polymerization. The conductive polymer films prepared from a copolymer of BTFTT and EDOT, a homopolymer of PBTFTT and PEDOT, showed characteristic redox properties pertinent to their monomers and homopolymers as determined by cyclic voltammetry (CV). The growth of organic films was estimated by an alpha-step and UV–visible spectral change. The film growth (thickness) was linearly correlated to the cycle numbers in CV for the electropolymerization. The electrodeposited organic nano-film showed a reversible photocurrent switching effect in a liquid electrolyte solution containing redox couple (Q/H₂Q) by the alternative UV irradiation (0.1 W/cm⁻²). Maximum photocurrent switching efficiency as well as fast response were obtained from the polymer film synthesized from a solution containing equivalent molar concentration of EDOT and BTFTT (1:1).     

Resonant infrared laser deposition of polymer-nanocomposite materials for optoelectronic applications

Polymers find a number of potentially useful applications in optoelectronic devices. These include both active layers, such as light-emitting polymers and hole-transport layers, and passive layers, such as polymer barrier coatings and light-management films. This paper reports the experimental results for polymer films deposited by resonant infrared matrix-assisted pulsed laser evaporation (RIR-MAPLE) and resonant infrared pulsed laser deposition (RIR-PLD) for commercial optoelectronic device applications. In particular, light-management films, such as anti-reflection coatings, require refractive-index engineering of a material. However, refractive indices of polymers fall within a relatively narrow range, leading to major efforts to develop both low- and high-refractive-index polymers. Polymer nanocomposites can expand the range of refractive indices by incorporating low- or high-refractive-index nanoscale materials. RIR-MAPLE is an excellent technique for depositing polymer-nanocomposite films in multilayer structures, which are essential to light-management coatings. In this paper, we report our efforts to engineer the refractive index of a barrier polymer by combining RIR-MAPLE of nanomaterials (for example, high refractive-index TiO₂ nanoparticles) and RIR-PLD of host polymer. In addition, we report on the properties of organic and polymer films deposited by RIR-MAPLE and/or RIR-PLD, such as Alq₃ [tris(8-hydroxyquinoline) aluminum] and PEDOT:PSS [poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate)]. Finally, the challenges and potential for commercializing RIR-MAPLE/PLD, such as industrial scale-up issues, are discussed.     

Donor-acceptor conjugated copolymer with high thermoelectric performance: A case study of the oxidation process within chemical doping

The doping process and thermoelectric properties of donor-acceptor(D-A)type copolymers are investigated with the representative poly([2,6-4,8-di(5-ethylhexylthienyl)benzo[1,2-b;3,3-b]dithiophene]3-fluoro-2-[(2-ethylhexyl)-carbonyl]thieno[3,4-b]thiophenediyl))(PTB7-Th).The PTB7-Th is doped by Fe Cl;and only polarons are induced in its doped films.The results reveal that the electron-rich donor units within PTB7-Th lose electrons preferentially at the initial stage of the oxidation and then the acceptor units begin to be oxidized at a high doping concentration.The energy levels of polarons and the Fermi level of the doped PTB7-Th remain almost unchange with different doping levels.However,the morphology of the PTB7-Th films could be deteriorated as the doping levels are improved,which is one of the main reasons for the decrease of electrical conductivity at the later stage of doping.The best electrical conductivity and power factor are obtained to be 42.3 S·cm^-1;and 33.9μW·mK^-1,respectively,in the doped PTB7-Th film at room temperature.The power factor is further improved to 38.3μW·mK^-1;at 75℃.This work may provide meaningful experience for development of D-A type thermoelectric copolymers and may further improve the doping efficiency.     

Ultrasound assisted one-pot, three-components synthesis of pyrimido[1,2-a]benzimidazoles and pyrazolo[3,4-b]pyridines: A new access via phenylsulfone synthon

A simple, facile, efficient and three-components procedure for the synthesis of pyrimido[1,2-a]benzimidazoles and pyrazolo[3,4-b]pyridines utilizing phenylsulfone synthon, under ultrasonic irradiation was developed.     

Dramatic reduction of the effect of nanoconfinement on the glass transition of polymer films via addition of small-molecule diluent

The effect of nanoconfinement on the glass transition temperature T(g) in thin polymer films is studied as a function of added small-molecule diluent or plasticizer. The decrease [increase] in T(g) found in nanoconfined, neat polystyrene [poly(2-vinyl pyridine)] is suppressed by added diluent, with 13-20 nm thick polystyrene films exhibiting bulk T(g) upon addition of 9 wt % pyrene or 4 wt % dioctylphthalate [corrected]. This is explained by a connection between the size scale of the cooperative dynamics associated with T(g), which decreases with added diluent, and the size scale of the nanoconfinement effect.     

AFM, SEM and GIXRD studies of thin films of red polycarbazolyldiacetylenes

In this paper we report the results of a morphological and structural investigation on film properties of a soluble polydiacetylene, the poly[1,6-bis(3,6-dihexadecyl-N-carbazolyl)-2,4-hexadiyne] (polyDCHD-HS). The red films of this polymer, prepared by standard spin-coating techniques, revealed absence of linear dichroism and birefringence in contrast with the ordered mesophases detected by powder X-ray studies. In order to interpret the optical behavior of this polymer, we performed AFM and SEM studies of polyDCHD-HS films spun on hydrophylic and hydrophobic glass substrates. We found the presence of surfaces organized in rod-like particles, more regularly oriented on the hydrophylic substrate. GIXRD studies, carried out on films sufficiently thick to allow the observation of the diffraction pattern, reveled the presence of a lamellar structure with a spacing of 3.22 nm. The low intensity of the diffraction peaks and the isotropic linear optical properties of the films show that the lamellar mesophases are not extended over large areas. These findings were compared with the data obtained from AFM and SEM studies on films of two other polydiacetylenes, the poly[1-(3,6-dihexadexyl-N-carbazolyl)-6-(N-carbazolyl)-2,4-hexadyine] (polya-DCHD) and the poly[1,6-bis(3,6-dipalmitoyl-N-carbazolyl)-2,4-hexadyine] (polyDPCHD), spun on hydrophylic glass substrate. The results confirmed the presence of nodular morphologies which seem to be a general characteristic of this class of materials. The particles organization appears instead related to the chemical nature of the substituents on the carbazolyl rings.     

Thermoluminescence of the blue light-emitting system based on poly(9-vinylcarbazole) doped with a pyrazoloquinoline dye

We have investigated the charge carrier trapping and recombination mechanisms in electroluminescent systems based on poly(9-vinylcarbazole)/2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazole blend, used as the matrix, and the deep blue light-emitting pyrazoloquinoline dye-1-H-pyrazolo[3,4-b]quinoline (PAQ8) dopant. The thermoluminescence studies have shown that the charge carrier trapping occurs on the dye molecules as well as on the matrix components. The traps localized on the PAQ8 molecules compete with the others available in the system, however at higher concentrations of the dye a role of these traps increases. Spectral analyses of the thermoluminescence have indicated that even at low concentration of PAQ8, the dye molecules constitute the dominating recombination centres in the system.     

Vertical phase separation in spin-coated films of a low bandgap polyfluorene/PCBM blend—Effects of specific substrate interaction

We report on the effect of the substrate on the vertical phase separation in spin-coated thin films of poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-5,5-4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole] (APFO-3) blended with [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM). Compositional depth profiles of the films are measured by dynamic secondary ion mass spectrometry (SIMS). We found that changing the substrate from silicon to gold affects the composition profile near the substrate interface. This is caused by a specific interaction between the polymer (APFO-3) and the gold surface, as confirmed by X-ray photoelectron spectroscopy (XPS). The composition profile in the area away from the substrate interface, as well as the enrichment of the free surface with APFO-3, remain however unaffected by the choice of substrate. The vertical composition was also analysed for APFO-3:PCBM films spin-coated on indium tin oxide (ITO) coated with a thin layer of (3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS).     

Influence of bridging atom on the vertical phase separation of low band gap bulk heterojunction solar cells

Vertical phase separation of the polymer and fullerene molecules in bulk heterojunction organic solar cells influences the exciton dissociation, charge carrier transport and collection. This work compares the vertical phase separation of poly[2,1,3‐benzothiadiazole‐4,7‐diyl[4,4‐bis(2‐ethylhexyl)‐4H‐cyclopenta [2,1‐b:3,4‐b′]dithiophene‐2,6‐diyl]] (C‐PCPDTBT):[6,6]‐phenyl C71 butyric acid methyl ester (PC₇₁BM) and poly[2,1,3‐benzothiadiazole‐4,7‐diyl[4,4‐bis(2‐ethylhexyl)‐4H‐cyclopenta [2,1‐b:3,4‐b′]dithiophene‐siloe2,6‐diyl]] (Si‐PCPDTBT):PC₇₁BM blend films, using X‐ray photoemission spectroscopy depth profiles. The difference between the two polymers is the bridging atom, which is carbon for C‐PCPDTBT and silicon for Si‐PCPDTBT. Si‐PCPDTBT exhibits enhanced polymer chain packing and crystallinity. We believe this enhanced chain packing provides a driving force during film drying which alters the vertical morphology. The different nature of vertical phase separation plays a role in determining the increased device performance observed for Si‐PCPDTBT:PC₇₁BM solar cells. (© 2014 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Nanoscale determination of surface orientation and electrostatic properties of ZnO thin films

Scanning force microscopy related techniques are applied to study surface nanoscale properties. We show that nanogoniometry can be combined with local electrostatic measurements – electrostatic force microscopy and Kelvin probe microscopy – to identify surface planes families and to study their local electrical properties. The scanning force microscopy techniques employed are analyzed and the correct way of acquiring and interpreting data is discussed in detail. The experiments performed on ZnO films grown along the nonpolar [112̄0] direction show that these films completely facet into {101̄1} and {101̄1̄} planes, which follow a well defined pattern of surface potential along the [0001] direction. This pattern is explained in terms of the different ionic termination – Zn or O ions – of the exposed facets. Finally, the presence of inversion domain boundaries is discussed. PACS 68.47.Gh; 73.30.+y; 68.37.-d; 73.63.-b     

2,7-Carbazole and thieno[3,4-c]pyrrole-4,6-dione based copolymers with deep highest occupied molecular orbital for photovoltaic cells

Three kinds of donor–acceptor (D–A) type photovoltaic polymers were synthesized based on 2,7-carbazole and thieno[3,4-c]pyrrole-4,6-dione (TPD). The conjugation of weakly electron (e)-donating 2,7-carbazole and strongly e-accepting TPD moieties yielded a deep highest occupied molecular orbital (HOMO) and its energy level was fine-controlled to be −5.72, −5.67 and −5.57 eV through the incorporation of thiophene (T), thieno[3,2-b]thiophene (TT) and bithiophene (BT) as a π-bridge. Polymer:[6,6]-phenyl-C₇₁ butyric acid methyl ester (PC₇₁BM) based bulk heterojunction solar cells exhibited a high open-circuit voltage (V_OC) in the range, 0.86–0.94 V, suggesting good agreement with the measured HOMO levels. Despite the high V_OC, the thiophene (or thienothiophene)-containing PCTTPD (or PCTTTPD) showed poor power conversion efficiency (PCE, 1.14 and 1.25%) because of the very low short-circuit current density (J_SC). The voltage-dependent photocurrent and photoluminescence quenching measurements suggested that hole transfer from PC₇₁BM to polymer depends strongly on the HOMO level of the polymer. The PCTTPD and PCTTTPD devices suffered from electron–hole recombination at the polymer/PC₇₁BM interfaces because of the insufficient energy offset between the HOMOs of the polymer and PC₇₁BM. The PCBTTPD:PC₇₁BM device showed the best PCE of 3.42% with a V_OC and J_SC of 0.86 V and 7.79 mA cm⁻², respectively. These results show that photovoltaic polymers should be designed carefully to have a deep HOMO level for a high V_OC and sufficient energy offset for ensuring efficient hole transfer from PC₇₁BM to the polymer.     

Self-organization effect in poly（3-hexylthiophene）： methanofullerenes solar cells

This paper studies the self-organization of the polymer in solar cells based on poly（3-hexylthiophene）： [6, 6]-phenyl C61-butyric acid methyl ester by controlling the growth rate of active layer. These blend films are characterized by UV-vis absorption spectroscopy, charge-transport dark J - V curve, x-ray diffraction pattern curve, and atomic force microscopy. The results indicate that slowing down the drying process of the wet films leads to an enhanced selforganization, which causes an increased hole transport. Increased incident light absorption, higher carrier mobility, and balanced carrier transport in the active layer explain the enhancement in the device performance, the power conversion efficiency of 3.43% and fill factor up to 64.6% are achieved under Air Mass 1.5, 100 mW/cm^2.     

共轭低聚物中光生分子间电荷转移态的第一性原理研究

We perform density functional theory calculations to investigate the polaron pair (charge transfer state) photo-generation in donor-acceptor oligomer methyl-capped (4,7-benzo[2,1,3]thiadiazole-2,6-(4,4-bis (2-ethylhexyl)-4H-cyclopenta[1,2-b;3,4-b'']dithiophene-4,7-benzo[2,1,3]thiadiazole)(CPDTBT).Results show that effective photo-generation of charge transfer state can happen in CPDTBT dimer when the group 4,7-benzo[2,1,3]thiadiazole (BT) in one monomer deviates against the conjugated plane (onset torsion angle is about 20°).The lower excitation energy (530 nm) can only generate the intramolecular excitonic state,while the higher excitation energy (370 nm) can generate the intermolecular charge transfer state,in good agreement with the experiment.Moreover,the mechanism of charge separation in CPDTBT oligomers is discussed.