Wide band-gap organic molecules containing benzodithiophene and difluoroquinoxaline derivatives for solar cell applications

Abstract

Two new semiconducting organic small molecules, namely BDTQ-BDT(EH) and BDTQ-BDT(OC), were prepared by attaching electron accepting 2,3-didodecyl-6,7-difluoro-5,8-di(thiophen-2-yl)quinoxaline (DTQ) unit on 2,6-position of electron donating 4,8-bis(2-ethylhexyloxy)benzo[1,2-b:4,5-b']dithiophene (BDT(EH)) and 4,8-bis(octyloxy)benzo[1,2-b:4,5-b']dithiophene (BDT(OC)) units. Molecule BDTQ-BDT(EH) showed higher thermal stability (5% weight loss temperature, T_d “349 ^оC), slightly lower band-gap (E_g “2.10?eV) and deeper highest occupied molecular orbital energy level (HOMO “–5.36?eV) level compared to those (T_d “336 ^оC, E_g “2.11?eV, and HOMO “–5.30?eV, respectively.) of the molecule BDTQ-BDT(OC). The organic solar cells (OSCs) made with the synthesized molecules as an electron donor and [6,6]-phenyl C₇₁ butyric acid methyl ester (PC₇₀BM) as an electron acceptor gave a maximum power conversion efficiency (PCE) of 1.20% and 0.83%, respectively, for BDTQ-BDT(EH) and BDTQ-BDT(OC). This study confirmed that the substituents attached on the 4,8-position of BDT unit greatly alter the properties of the resulting molecules.     

Structure engineering of small molecules for organic solar cells

Abstract

Two 1,3-bis(thiophen-2-yl)?5,7-bis(2-ehtylhexyl)benzo-[1,2-c:4,5-c]-dithiophene-4,8-dione (BDD) based small molecules, SM1 and SM2 are designed and synthesized by incorporating benzodithiophene (BDT) central core, BDD dual accepting units and 3-ethyl rhodamine as endcap group with various number of BDT units. We systematically investigated the synthesis, optical and electrochemical properties, and photovoltaic characteristics of these donor materials. The number of BDT units have a significant influence on Jsc due to interconnected structure and results in a broader absorption on thin film. The inverted devices employed for both small molecules exhibited power conversion efficiencies of 0.41% for SM1 and 0.82% for SM2.     

Synthesis of A-D-A type quinoxaline-based small molecules for organic photovoltaic cells

Abstract

We have synthesized two acceptor-donor-acceptor (A-D-A) type quinoxaline-based small molecules for organic photovoltaic cells (OPVs). To construct the A-D-A architecture, the electron-accepting quinoxaline derivative (Qx) was attached on both ends of the electron-donating benzodithiophene (BDT) unit via the Stille coupling reaction. After the confirmation of the structural features, the optical and electrochemical characteristics and the photovoltaic properties of the two small molecules were investigated. A typical inverted-type device with the configuration of ITO/ZnO/small molecules: PC₇₁BM/MoO₃/Ag was fabricated and examined. It has been observed that the performances of OPVs were improved by the incorporation of the additional thiophene linkage between the BDT and Qx moieties. Therefore, this study can provide insights into the design and structure–property correlation of quinoxaline-based organic small molecules for OPVs     

Design, synthesis, and structure of novel cesium receptors

The podand, bis(2-methoxyphenoxy)m-xylene (1), was designed and synthesized as a potential host for the cesium ion. Its structure was determined by single crystal X-ray diffraction. It crystallizes in P2₁/c with cell dimensions: a = 8.5723(7) Å, b = 8.3931(14) Å, c = 25.2879(26) Å, = 96.224(9), and V = 1808.7(4) ų. A crown derivative, tribenzo-21-crown-6 (2), was also prepared and structurally characterized. It also crystallizes in P2₁/c with cell dimensions: a = 15.5825(13) Å, b = 15.8648(16) Å, c = 8.8266(7) Å, = 95.247(6), and V = 2172.9(3) ų. The structures exhibit hydrogen bonding, and are evaluated in terms of complementarity and preorganization for cesium binding.     

Molecular Design of Carbazole-based Dyes and the Influence of Alkyl Substituent on the Performance of Dye-Sensitized Solar Cells

Carbazole is an alternant polycyclic aromatic hydrocarbon consisting of three fused rings with a large, aromatic system, containing nitrogen atom showing extensive electron delocalization. In this work, carbazole applied as π-conjugated bridge to construct electron donor–π–electron acceptor (D–π–A) organic dyes, where barbutiric acid and thiazolidine-2,4-dione as electron acceptor. The effects of these three acceptors and length of alkyl on the performance of the DSSCs were investigated systematically along with their photophysical and photo electrochemical properties. These series of organic dyes include (B-CH, B-C B, DT-CB, DB-CB). Our investigation indicate among dyes containing butyl as same donor, DT-CB exhibited the maximum overall conversion efficiency of 1.44% and from dyes by deferent electron donor B-CH shows conversion efficiency of 1.47%.     

Hydrothermal synthesis of [Mn(HTPO)(BIPY)] (H3TPO = tris-(4-carboxylphenyl)phosphine oxide): a crosslinked coordination polymer

The hydrothermal synthesis and crystal structure of the title compound is reported. The structure consists of 1-D looped chains with the HTPO ligand binding through the phosphoryl and two carboxylate oxygens to manganese atoms. The carboxylic acid group is hydrogen bonded to adjacent chains forming a 2-D hydrogen bonded network. The crystals are triclinic and the space group isP-1 with a = 11.6767(8) Å, b = 10.8680(8) Å and c = 11.4232(87rpar; Å = 92.301(2)°, = 106.932(2)° and = 103.2390(10)° V = 1341.02(16) ų; Z = 2.     

电沉积法制备CdS薄膜及其性能研究

采用电沉积法制备了CdS薄膜.分别用XRD及SEM分析了薄膜的结构和表面形貌.研究了不同温度和不同沉积电压对薄膜表面硫与镉的化学成分比的影响.最佳的沉积电压为2.5～3V之间.制作了ITO/n-CdS/p-SnS/Ag结构的太阳能电池,在100mW/cm2的光强下其开路电压0.2V,短路电流13.2mA/cm2,填充因子0.31,转换效率0.81;.     

Solution-processible Cd-doped ZnO nanoparticles as an electron transport layer to achieve high performance polymer solar cells through improve conductivity and light transmittance

Abstract

In this work, electron transport layers (ETLs) with high charge transfer ability were prepared by doping ZnO nanoparticles with different concentrations of cadmium(Cd). The inverted polymer solar cell based on PTB7-Th: PC₇₁BM as active layer and various concentrations Cd-doped ZnO (CZO) as ETLs were fabricated. The PCE of the device with optimized Cd content in the ZnO film was about 14.7% larger than that of the pure ZnO-based cells. The cadmium-doped ZnO(CZO) is a good candidate to be used as a high-quality transparent electrode in solar cell applications.     

Synthesis and characterization of new nematic liquid crystalline compounds-based thiophene units

Four new liquid crystalline thiophene compounds (M1?M4) with a long flexible spacer were prepared. Their structures were characterized by Fourier transform infrared and proton nuclear magnetic resonance. The mesomorphism and thermal stability were investigated with differential scanning calorimetry, polarizing optical microscopy, and thermogravimetric analysis. The photo-physical properties were evaluated using ultraviolet/visible spectroscopy and photoluminescence. M1?M4 all showed thermotropic mesogenic properties with excellent thermal stability, and exhibited nematic threaded texture, droplet texture, and Schlieren texture on heating and cooling cycles. The effect of flexible spacer and terminal groups on mesomorphic and spectroscopic property is discussed. The experimental results demonstrated that the tendency toward melting temperature (Tm) decreased, while isotropic temperature (Ti) increased with increasing the flexible spacer length. In CHCl₃ solution, these thiophene compounds displayed an intense broad absorption band peaking within 230–340 nm and a maximum fluorescent emission wavelength at 426–439 nm.     

本征微晶硅薄膜和微晶硅电池的制备及其特性研究

本文对VHF-PECVD制备的本征微晶硅薄膜和电池进行了电学特性和结构特性方面的测试分析研究.电学测试结果给出制备薄膜的激活能为0.51eV,符合电池对材料的电学参数要求;拉曼散射谱测试结果计算得到样品的晶化率为63;;X射线衍射结果也证明材料晶化,同时(220)方向择优;首次在国内用VHF-PECVD方法制备出效率为5;的微晶硅电池(Jsc=21mA/cm2,Voc=0.46V,FF=51;,Area=0.253cm2).     

钙钛矿太阳能电池的效率和稳定性研究

近年来,有机-无机钙钛矿太阳能电池由于卓越的光电性能和极低的材料成本引起广泛关注,更被认作是一种前景广阔的光伏材料.目前,钙钛矿太阳能电池的光电转换效率已经超过22;,展示了极大的发展潜力,但对紫外线辐射和水的长期稳定性差.因此,关于钙钛矿太阳能电池的研究主要集中在电池的高效性和稳定性.本文对提高钙钛矿太阳能电池的效率和稳定性的多种方法进行综述,介绍了近期获得的突破,旨在为实现提高钙钛矿太阳能电池的高效性和稳定性提供基本依据.     

Controlled synthesis of SrCrO4 crystals with different morphologies

Rod‐shape, branch‐shape, bouquet‐shape and claw‐shape SrCrO₄ crystals were synthesized through biomembrane/organic‐addition supramolecular templates. The shapes are mainly changed with variance of the organic reagents and organic membranes. Most of the morphologies haven't been reported in the literature. This method may meet with the requirements to synthesize materials of various morphologies and size by using different supramolecular templates. This paper discusses how to control crystals' growth by supramolecular templates. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

光学微腔型a-Si薄膜电池陷光结构设计

先基于频域有限差分法和a-Si材料的有效吸收波长范围,利用光场分布、通光效率和有源层吸收谱等优化了有源层厚度为300 nm的a-Si电池用光学微腔陷光结构的缓冲层厚度和光学微腔通光孔尺寸,并对电池光电流密度谱、总电流密度和电池输出参数进行了计算分析.研究表明:缓冲层厚度为2.6 μm,通光孔直径Φ=D×0.8/8时,电池有源层具有最大的吸收效率;优化电池的短路电流为25.9225 mA/cm2,优于其它陷光结构获得的短路电流.     

Small molecular electrolytes as the interlayer for enhanced performance of organic solar cellsExperimental

Abstract

New non-conjugated small molecules (C4-OH and C6-OH) were synthesized and applied to the inverted organic solar cells (OSCs) as the cathode interlayer (CIL). The power conversion efficiencies (PCEs) of 9.35 and 9.21% were obtained in the device based on ZnO/C4-OH and ZnO/C6-OH, which are better than those of pristine ZnO (8.74%). The work function of ZnO/C4-OH and ZnO/C6-OH are also decreased from ?4.5?to ?4.27?eV and ?4.37?eV, respectively. Consequently, OSCs with two small molecules exhibited enhanced photovoltaic properties due to the formation of interface dipole.     

Solution-processed small-molecule organic solar cells based on diketopyrrolopyrrole and perlyene derivatives with coplanar structures

ABSTRACT

A series of small-molecules (SMs) based on coplanar perylene unit coupled with diketopyrrolopyrrole chromophoric core exhibit broad absorption in the range of 500–800 nm and low bandgap energise of 1.6–1.7 eV. The power conversion efficiency approximately reach at 0.4% under 1.5 G illumination is achieved for organic solar cells based on a small-molecule bulk heterojunction system consisting of SMs as a donor and [6,6]-phenyl-C₆₁-butyric acid methyl ester (PC₆₁BM) as an acceptor.     

Hydrothermal synthesis and crystal structure of a new europium fumarate compound

The complex {[Eu₂F₃4H₂O]3H₂O}_n (H₂F = fumaric acid) has been synthesized and structurally characterized by single crystal X-ray diffration methods. The complex crystallizes in the monoclinic system with space group P2₁/n, lattice parameters a = 9.475(3) Å, b = 14.700(5) Å, c = 14.810(4) Å, = 90, = 91.250(5), = 90, V = 2062.1(11) ų, Z = 4, D_calc = 2.487 Mg/m³. The Eu(III) center is in distorted tricapped trigonal prism coordination environment that is coordinated by nine oxygen atoms, seven from five F^2– groups, two from two water molecules. Eu(III) ions are connected into three-dimensional coordination network structure by the oxygen atoms of the carboxyl groups and hydrogen bonds.     

新型配位聚合物[Ni(C6H4NO2)2(H2O)4]n的水热合成和晶体结构

以NiCl2·6H2O和4-氰基吡啶为原料,在中温水热反应条件下,合成了一种新型配位聚合物[Ni(C6H4NO2)2(H2O)4]n单晶体,并对其进行了元素分析、红外光谱表征和X射线单晶衍射测定.该配位聚合物属三斜晶系,P-1空间群,a=0.6298(4)nm,b=0.6907(4)nm,c=0.9243(5)nm,α=96.437(8)°,β=105.184(9)°,γ=113.314(9)°,V=0.3456(3)nm3,Z=2,dc=1.802 g/cm3,μ=1.452mm-1,F(000)=194,R1=0.0309,R2=0.0753.该晶体通过配位键的连接和分子间氢键相互作用形成三维的网状结构.     

Transient analysis of the cooling process and influence of bottom insulation on the stress in the multicrystalline silicon ingot

Directional solidification is one of the most popular techniques for massive production of multicrystalline silicon. After growth and annealing, the ingot is cooled down by a designed cooling process, which is initialized by descending bottom insulation, and then is controlled both by power ramp‐down rate and by motion of the bottom insulation. Thermal stress is piled up during cooling, and associated crystal defects, such as dislocation and micro‐cracks, may generate and propagate in the ingot. In the paper, transient modeling is applied to study the effect of bottom insulation on the cooling process. Temperature, velocity and thermal stress fields are obtained with linear, parabolic and sinusoidal motions of the insulation. The measured and predicted temperatures at two points of the ingot are found consistent. Distributions of von Mises stress in the ingot at different cooling time are obtained, and the maximum von Mises stresses are presented as a function of the cooling time. Specifically, dislocation‐free regions, evaluated by the critical resolved shear stress model, at certain cooling time, and area fractions of the regions as a function of the cooling time are proposed. The linear motion is further discussed with different moving rates, considering its wide applications in the current industry and convenient realization in control.     

Solvothermal synthesis and growth mechanism of asymmetric ZnO hierarchical structures in diethylene glycol with ammonia solution

Several novel asymmetric ZnO hierarchical structures were synthesized in diethylene glycol (DEG) with different amount of ammonia solution via solvothermal process. The submicron‐rods or nanorods as the building units are distributed on the two sides in an asymmetric manner, resulting in formation of the shiitake‐like or bouquet‐like morphology. A possible formation mechanism was proposed on the basis of the experimental result. The consumption of the precursor could lead to a two‐step nucleation and growth process. The relative content of the [Zn(OH)₄]²⁻ and the [Zn(NH₃)₄]²⁺ precursors varies with the amount of ammonia solution, which affect the size and morphology of the asymmetric structures. The [Zn(OH)₄]²⁻ complex and the [Zn(NH₃)₄]²⁺ complex are absorbed on the positive (0001)‐Zn polar surface and the negative (000–1)‐O polar surface respectively, which lead to the alteration of growth rate of these polar surfaces.     

新型配位聚合物[Co(pda)2(H2O)2]n的水热合成和晶体结构

以CoCl2·6H2O和3-(3-吡啶基)丙烯酸(pda)为原料,在中温水热反应条件下,合成了一种新型配位聚合物[Co(pda)2(H2O)2]n单晶体,并对其进行了元素分析、红外光谱表征、TGA-GTA分析和X射线单晶衍射测定.该配位聚合物属单斜晶系,P2(1)/c空间群,晶胞参数为a=1.6958(8)nm;b=0.5466(3)nm;c=1.8034(8)nm;α=90°;β=106.209(7)°;γ=90°;Mr=391.24;V=1.6051(13)nm3;Z=4;dc=1.619g/cm3;μ=1.106mm-1;F(000)=804;R1=0.0367;wR2=0.0711.该晶体通过配位键的连接形成二维结构,又通过分子间氢键和π-π相互作用形成三维的网状结构.