Nanostructured organic and hybrid solar cells

This Progress Report highlights recent developments in nanostructured organic and hybrid solar cells. The authors discuss novel approaches to control the film morphology in fully organic solar cells and the design of nanostructured hybrid solar cells. The motivation and recent results concerning fabrication and effects on device physics are emphasized. The aim of this review is not to give a summary of all recent results in organic and hybrid solar cells, but rather to focus on the fabrication, device physics, and light trapping properties of nanostructured organic and hybrid devices.     

Engineering spin propagation across a hybrid organic/inorganic interface using a polar layer

Spintronics has shown a remarkable and rapid development, for example from the initial discovery of giant magnetoresistance in spin valves to their ubiquity in hard-disk read heads in a relatively short time. However, the ability to fully harness electron spin as another degree of freedom in semiconductor devices has been slower to take off. One future avenue that may expand the spintronic technology base is to take advantage of the flexibility intrinsic to organic semiconductors (OSCs), where it is possible to engineer and control their electronic properties and tailor them to obtain new device concepts. Here we show that we can control the spin polarization of extracted charge carriers from an OSC by the inclusion of a thin interfacial layer of polar material. The electric dipole moment brought about by this layer shifts the OSC highest occupied molecular orbital with respect to the Fermi energy of the ferromagnetic contact. This approach allows us full control of the spin band appropriate for charge-carrier extraction, opening up new spintronic device concepts for future exploitation.     

Optical management for efficiency enhancement in hybrid organic-inorganic lead halide perovskite solar cells

In a few years only, solar cells using hybrid organic–inorganic lead halide perovskites as optical absorber have reached record photovoltaic energy conversion efficiencies above 20%. To reach and overcome such values, it is required to tailor both the electrical and optical properties of the device. For a given efficient device, optical optimization overtakes electrical one. Here, we provide a synthetic review of recent works reporting or proposing so-called optical management approaches for improving the efficiency of perovskite solar cells, including the use of anti-reflection coatings at the front substrate surface, the design of optical cavities integrated within the device, the incorporation of plasmonic or dielectric nanostructures into the different layers of the device and the structuration of its internal interfaces. We finally give as outlooks some insights into the less-explored management of the perovskite fluorescence and its potential for enhancing the cell efficiency.     

碘盐对聚合物凝胶电解质及染料敏化太阳电池性能的影响

通过简单方法合成了一种新型有机碘盐N-甲基吡啶碘，以苯乙烯-丙烯腈共聚物（AS树脂）为聚合物凝胶电解质基体，丙烯碳酸酯及乙烯碳酸酯双组分有机溶剂为液相，制备了含有机碘盐（N-甲基吡啶碘）和无机碘盐（NaI）的AS树脂基聚合物凝胶电解质，比较了两种碘盐对聚合物凝胶电解质导电性能及染料敏化纳米晶太阳电池光电性能的影响，发现含有机碘盐的聚合物凝胶电解质具有较高的电导率，所制备的DSSC光电性能也较好。     

Mesoscopic 2-D ordering of inorganic/organic hybrid materials

Organic–inorganic hybrid materials with micronsized (i.e., mesoscopic) network structures are expected to have interesting properties and applications in various fields, such as separation, catalysis, biomineralization, or quantum optics. Here a new method is introduced to produce thin films of two-dimensionally ordered honeycomb structures. Casting a chloroform solution of a mixture of organic amphiphiles with metal acetylacetonates or -alkoxides at high atmospheric humidity leads to the formation of a closely packed layer of water droplets on top of the organic solvent. The water acts as a template, After evaporation of the chloroform and the water, a honeycomb structure remains. Pyrolysis of the metal alkoxides films lead to the formation of microporous metal oxide (e.g., anatase, one of the catalytic active titanium oxides).     

Role of majority and minority carrier barriers silicon/organic hybrid heterojunction solar cells

A hybrid approach to solar cells is demonstrated in which a silicon p-n junction, used in conventional silicon-based photovoltaics, is replaced by a room-temperature fabricated silicon/organic heterojunction. The unique advantage of silicon/organic heterojunction is that it exploits the cost advantage of organic semiconductors and the performance advantages of silicon to enable potentially low-cost, efficient solar cells.     

Water-processed self-assembles of monolayers as interface modifier for ZnO/P3HT hybrid solar cells

Benzoic acid based molecules were used for surface modification of ZnO nanorods as self-assembled monolayers (SAMs) in order to improve the interface interaction between ZnO and poly(3-hexylthiophene) in hybrid solar cells. The dipole moment of the molecules and the solvent used for the surface modification were investigated in relation to the performance of the hybrid devices. A linear relationship between the dipole moment of the interface modifiers and the open-circuit voltage (V_oc) of the devices were found. The V_oc are enhanced by the use of the molecules with their dipole moment pointing away from the ZnO surface and vice versa. The enhancement in V_oc is attributed to the shift of the vacuum level of ZnO when the surface is modified with the SAMs. When water was used as the solvent for surface modification process, aggregate was found in the solution state. This implies an ordered orientation of SAMs attached onto the ZnO surface, resulting in the improvement of the V_oc. An enhancement in the incident photon to current efficiency spectra was also obtained in the devices prepared from aqueous solution. The SAMs prepared from aqueous solution have better charge collecting properties in comparison with that prepared from ethanol solution.     

ZnO纳米棒/聚合物混合型太阳电池

在介绍有机太阳电池工作原理及研究进展的基础上,综述了ZnO纳米棒/聚合物混合型太阳电池的制备方法,详细讨论了ZnO电极处理、溶剂的选择、退火、有机功能材料的选择等因素对器件性能的优化机制,并就提高器件性能的途径提出作者的见解.     

有机生色团掺杂有机／无机复合基质非线性光学材料的制备与性能

以4-[乙基-（2-羟乙基）胺]-4’-硝基偶氮苯（DRl）为生色团，甲基丙烯酸甲酯（MMA）和正硅酸乙酯frEOS）为先体，通过原位溶胶-凝胶技术制备了新型的以PMMA／SiO2复合材料为掺杂基质的二阶非线性光学杂化材料，并运用提拉法在洁净的ITO导电玻璃上制备出均匀、透明的厚度为1μm左右的杂化薄膜。DSC测得杂化材料的玻璃化转变温度为130℃；二次谐波产生（SHG）测量结果表明杂化薄膜在电晕极化后二阶非线性系数d33为1．02×10^7esu；用UV-vis光谱对杂化膜在极化前后的取向和取向稳定性进行的研究表明此材料具有较高的取向度，且常温下的取向稳定性也较好，60d后取向序参数φ仍有初始值的85％。     

Prepare organic/inorganic hybrid nonlinear optical material containing two-dimensional spindle-type chromophores

In this paper, functionalized alkoxysilane dye (ICTES-STC) was formed by the reaction of two-dimensional spindle-type chromophores (STC) with 3-isocyanatopropyltriethoxysilane (ICTES). The transparent films having silica network matrix and covalently bonded chromophores were fabricated via the sol-gel process. From TGA thermogram, the initial decomposition temperature of the hybrid film was determined to be 269 °C. The electro-optic (EO) coefficient (r₃₃) of the poled films was measured to be around 12 pm/V by Teng-Man technique. The thermal stability of the NLO coefficient of the film was investigated by the depoling experiment and temporal decay test, and the result showed that the hybrid film had a good thermal stability, implying its potential applications for EO devices.     

Layered inorganic/organic mercaptopropyl pendant chain hybrid for chelating heavy cations

Heavy metal sorbents with uptake capacities for divalent cadmium and lead cation removal from aqueous solutions have been synthesized by grafting mercaptopropyltrimethoxysilane onto the surface of two different precursors obtained from lamellar ilerite, its acidic and the cetyltrimethylammonium exchanged forms. The organofunctionalization was carried out by two different procedures: reflux and solvent evaporation methodologies. Elemental analysis data based on carbon content gave 1.37 and 3.53 mmol of organic pendant groups per gram of hybrid by the reflux method, when starting from acidic ilerite and the surfactant form. X-ray diffraction corroborated the maintenance of the original crystallinity. Infrared spectroscopy and nuclear magnetic resonance for ²⁹Si and ¹³C nuclei are in agreement with the success of the proposed method. The sulfur basic centers attached to the lamellar structure are used to coordinate both cations at the solid/liquid interface. The isotherms were obtained through the batchwise process and the experimental data were adjusted to the Freundlich model. The maximum sorption capacities of 5.55 and 5.12 mmol g⁻¹ for lead and 6.10 and 7.10 mmol g⁻¹ for cadmium were obtained for organofunctionalized ilerite and its surfactant form, synthesized by reflux methodology. This behavior suggested that these hybrids could be employed as promising sorbents with a polluted system.     

Photofunctional terbium centered inorganic/organic hybrid material with the functionalized 5-dihydroxybenzoate linkage

In this study, silica-based organic-inorganic hybrids were prepared using sol-gel methods. A new kind of monomer (DHBA-TESPI) was derived by modifying the double hydroxyl groups of 3, 5-dihydroxybenzoic acid (DHBA) with 3-(triethoxysilyl)-propyl isocyanate (TESPI) through the addition reaction. Then, the obtained compound and tetraethoxysilane (TEOS) were used as the inorganic and organic counterparts respectively. Coordination reaction between Tb³⁺ and the carboxylic groups of the monomer happen simultaneously. IR, NMR, UV/Vis absorption, low-temperature phosphorescence spectroscopy and fluorescence spectroscopy were used to characterize the hybrids. The final materials exhibited strong green-colored fluorescence (Tb³⁺), which can be explained by the intramolecular energy transfer caused by coordination of the organic counterpart. The spectroscopic data also revealed that the triplet state energy of the organic ligand matches the emissive energy level of Tb³⁺.     

Crystallization behavior of PA6/SiO2 organic–inorganic hybrid material

Poly 2-hydroxy propylmethacrylate-methyl methacrylate/SiO₂ (PHPMA-MMA/SiO₂), an active composite was used to synthesize polyamide-6/SiO₂ (PA6/SiO₂) organic–inorganic hybrid materials via blending method. X-ray diffraction analysis (XRD) results showed that the addition of PHPMA-MMA/SiO₂ composite induced PA6 to transit from α to γ crystal form. The nonisothermal crystallization kinetics of PA6 and PA6/SiO₂ hybrid materials was investigated by differential scanning calorimetry (DSC). Jeziorny method derived from Avrami analysis and a method developed by Liu were employed to describe the nonisothermal crystallization process of PA6 and PA6/SiO₂ hybrid materials. Based on our experimental data, if the relative degree of crystallinity was approximately 60% or more, the Jeziorny method was not valid to describe the nonisothermal crystallization process, while Liu method was successful to describe the whole nonisothermal crystallization process. When X(t) was below about 60%, the crystallization rates of PA6 and PA6/SiO₂ hybrid materials were very approximate, but when X(t) was approximately 60% or more, the crystallization rate of PA6 was quicker than that of PA6/SiO₂ hybrid materials. Moreover, the addition of PHPMA-MMA/SiO₂ composite decreased the crystallization activation energy ΔE calculated by Kissinger equation because of the γ transition.     

新型POSS基有机/无机杂化分子发光材料的制备及聚集效应研究

有机发光材料在电致发光与显示器件领域有着非常广泛的应用。以具有高荧光量子产率的长共轭芴类衍生物2-乙炔基-7-(4-(4-甲氧基苯乙烯基)苯乙烯基)-9,9-二辛基芴(EMOF)和POSS(T8H8)为原料,通过硅氢化反应制备了POSS基有机/无机杂化分子发光材料(EMOF-POSS),并用FT-IR、1H-NMR和13C-NMR对其结构进行了表征。通过紫外-可见和荧光光谱研究了EMOF和EMOF-POSS在不同比例的THF/H2O混合溶剂中的聚集效应,并对两者的热性能进行了测试。结果表明,EMOF-POSS不仅具有较好的热稳定性,而且有效地降低了荧光生色团的聚集,从而提高了材料的荧光量子产率(ΦFL)和发光性能。     

A microstructural study on the surface and interface of CdTe/CdS solar cells

The surface and interface properties of CdTe/CdS solar cells, including interfacial mixing, surface and interface geometrical morphology, CdTe grain size and preferential crystal orientation of CdTe layers were studied using Auger electron spectroscopy (AES) depth profiling, atomic force microscopy (AFM), Fourier transform infrared (FTIR) spectroscopy, optical reflectance (OR) and X-ray diffraction (XRD) techniques. The correlation between the surface and interface properties and CdTe/CdS solar cell performance was also investigated. AES depth profiling was used to analyse the interdiffusion between the CdTe and CdS layers. Atomic force microscopy (AFM) suggests that the interfacial geometrical morphology has a significant influence on the photovoltaic property of CdTe/CdS solar cells. Rough interfaces tend to increase the photovoltaic conversion efficiency of solar cells because of multiple reflections. X-ray diffraction shows that polycrystalline CdTe/CdS solar cells with higher efficiencies appear to be orientated with more (1 1 1) planes of CdTe parallel to the macrosurface, but CdTe single crystals with differently indexed surface planes show almost the same reflection behaviour. Further theoretical and experimental analyses are therefore needed to clarify this observation. This revised version was published online in July 2006 with corrections to the Cover Date.     

氟硅改性丙烯酸酯有机/无机杂化无皂乳液制备及性能表征

以正硅酸乙酯（TEOS）为水解前驱体制得二氧化硅（SiO2）,并通过硅烷偶联剂（KH570）表面改性后,与全氟烷基乙基丙烯酸酯（FM））等乙烯基单体聚合,通过无皂乳液聚合方法制备了氟硅改性丙烯酸酯有机/无机杂化无皂乳液。FT-IR分析表明,TEOS水解为SiO2,并与丙烯酸酯单体、氟单体参与了共聚反应;采用TEM及AFM对乳胶粒的形态结构进行表征,发现乳胶粒分布较为均一,平均粗糙度和致密程度较高;DLS分析表明乳液平均粒径为49.49nm;接触角测试表明氟单体、硅溶胶及KH570的加入显著提高了涂膜的防水性。     

Single-molecule charge transfer and bonding at an organic/inorganic interface: tetracyanoethylene on noble metals

We have studied the structural and electronic properties of tetracyanoethylene (TCNE) molecules on different noble-metal surfaces using scanning tunneling spectroscopy and density functional theory. Striking differences are observed in the TCNE behavior on Au, Ag, and Cu substrates in the submonolayer limit. We explain our findings by a combination of charge-transfer and lattice-matching properties for TCNE across substrates that results in a strong variation of molecule-molecule and molecule-substrate interactions. These results have significant implications for future organic/inorganic nanoscopic devices incorporating molecule-based magnetism.