有机半导体光伏打电池--共轭聚合物及其与C60的复合体系

近年来，有机半导体太阳能电池引起科学工作者的极大兴趣，共轭聚合物/60复合体系在光伏打电池中的应用更是成为其中一个新的研究热点，文中介绍了有机半导体太阳能电池研究的背景，进展情况及存在的问题，并式材料合成，器件研究，机理探讨，薄膜制备等几个方面总结了文章作者在这一领域的研究工作进展。     

稀释溶剂对PEDOT：PSS薄膜和有机太阳能电池性能的影响

采用喷涂技术制备聚3,4-乙撑二氧噻吩：聚苯乙烯磺酸盐（PEDOT：PSS）有机层薄膜,系统研究了乙醇、去离子水、甲醇、异丙醇和乙二醇等稀释溶剂对PEDOT：PSS薄膜形貌、透过率及导电性能的影响。将PEDOT：PSS薄膜应用于有机太阳能电池器件的制备,研究了不同溶剂对器件性能的影响。实验结果表明：采用乙醇稀释PEDOT：PSS溶液,能有效抑制PEDOT：PSS颗粒团聚,降低薄膜粗糙度,提高薄膜的透过率和导电性。以其制备的太阳能电池器件的能量转换效率明显高于其他溶剂稀释,转换效率为2.66%。     

Interfacial processes in small molecule organic solar cells

This paper presents an overview of the recent progress of small molecule organic solar cells mainly based on the previous worksof our group. We will mainly focus on the interfacial processes in the cells. The dissociation of excitons at electrode/organic andorganic/organic interfaces can be directly observed by transient photovoltage measurements. A simple model including dissociationof excitons at the interface and drift of free carriers in the built-in field is proposed to explain the observed signals of ...     

有机共混结构叠层太阳电池的研究进展

有机太阳电池由于质轻、价廉、柔性,受到人们的广泛关注.单个有机材料只能吸收部分太阳光,叠层结构的太阳电池将不同吸收带隙的有机材料通过中间层连接起来,既能充分吸收太阳光,又能提高太阳电池的开路电压或短路电流.本文综述了近年来有机共混结构叠层太阳电池的研究进展,介绍了各种叠层有机太阳电池的结构、原理及性能,阐述了国内外有机叠层太阳电池研究的现状及存在问题,为高性能有机太阳电池的研究提供有价值的参考.     

Effective absorption enhancement in small molecule organic solar cells using trapezoid gratings

We demonstrate that the optical absorption is enhanced in small molecule organic solar cells by using a trapezoid grating structure. The enhanced absorption is mainly attributed to both waveguide modes and surface plasmon modes, which is simulated by using finite-difference time-domain method. The simulated results show that the surface plasmon along the semitransparent metallic Ag anode is excited by introducing the periodical trapezoid gratings, which induce the increase of high intensity field in the donor layer. Meanwhile, the waveguide modes result in a high intensity field in acceptor layer. The increase of field improves the absorption of organic solar cells significantly, which is demonstrated by simulating the electrical properties. The simulated results also show that the short-circuit current is increased by 31% in an optimized device, which is supported by the experimental measurement. Experimental result shows that the power conversion efficiency of the grating sample is increased by 7.7%.     

Laser induced forward transfer of conducting polymers

We report on laser printing of conducting polymers directly from the solid phase. Laser induced forward transfer is employed to deposit P3HT:PCBM films on glass/ITO/PEDOT:PSS substrates. P3HT:PCBM is widely used as the active material in organic solar cells. Polyaniline films, which are also printed by laser induced forward transfer, find many applications in the field of biotechnology. Laser printing parameters are optimized and results are presented. To apply solid-phase laser printing, P3HT:PCBM films are spun cast on quartz substrates, while aniline is in-situ polymerized on quartz substrates.     

镀膜法改善有机薄膜太阳能电池光学性能

有机活性材料的低载流子迁移率使得有机光伏电池的电极收集到的电荷较少。增加活性层光吸收能够增加激子的产生数从而增加电极收集到的电荷,提升器件的性能。通过对器件模拟的方法,研究以P3HT：PCBM为活性层的薄膜太阳能电池的光学性能。 在此基础上,提出采用镀多层高反射膜的方法改善电池器件的光学性能。结果表明：活性层厚度对电池器件的光吸收起到主导作用;镀多层高反射膜在活性层厚度小于160 nm、Ag厚度小于20 nm时能大幅度改善电池器件的光学性能,光生激子总数随活性层厚度的增加而迅速增多,并且在活性层厚度约为150 nm时为一个最佳值。     

Surface modulation of halide perovskite films for efficient and stable solar cells

As the main distribution place of deep-level defects and the entrance of water, the interface is critical to determining both the power conversion efficiency (PCE) and the stability of perovskite solar cells (PSCs). Suitable interface design can dramatically passivate interface defects and optimize energy level alignment for suppressing the nonradiative recombination and effectively extracting the photogenerated carriers towards higher PCE. Meanwhile, a proper interface design can also block the interface diffusion of ions for high operational stability. Therefore, interface modification is of great significance to make the PSCs more efficient and stable. Upon optimized material choices, the three-dimensional halide perovskite graded junction layer, low-dimensional halide perovskite interface layer and organic salt passivation layer have been constructed on perovskite films for superior PSCs, yet a systematic review of them is missing. Thus, a guide and summary of recent advances in modulating the perovskite films interface is necessary for the further development of more efficient interface modification.     

Thermally evaporated Ag nanoparticle films for plasmonic enhancement in organic solar cells: effects of particle geometry

We report on the simple fabrication of Ag NP films via thermal evaporation and subsequent annealing. The NPs are formed on indium tin oxide electrodes, coated with PEDOT:PSS and implemented into PCPDTBT:PC70BM solar cells. Scanning electron microscopy and atomic force microscopy are used to determine the size distributions and surface coverage of the NP film. We apply finite‐difference time‐domain techniques to model the optical properties of different nanoparticle films and compare this with the absorption properties of the organic active layer. The simulations demonstrate that the absorption and scattering efficiency of the particles are very sensitive to particle geometry. Solar cells prepared with window electrodes containing NP layers with less surface coverage, show a 14.8% improvement in efficiency. We discuss variations in the external quantum efficiency of the devices in terms of forward scattering and parasitic absorption losses induced by the NP layer. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Inverted organic solar cells comprising low-temperature-processed ZnO films

Inverted organic solar cells are fabricated using low-temperature-annealed ZnO film as an electron transport layer. Uniform ZnO films were prepared by spin coating a diethylzinc (DEZ) precursor solution in air, followed by annealing at 100 °C. Organic solar cells prepared on these ZnO films with a 1:1 P3HT:PCBM blend as the active layer show a high power conversion efficiency of 4.03 %, which is more than 10 % higher than the PCE of solar cells comprising ZnO prepared via a high-temperature sol–gel route.     

A simple encapsulation method for organic optoelectronic devices

The performances of organic optoelectronic devices, such as organic light emitting diodes and polymer solar cells,have rapidly improved in the past decade. The stability of an organic optoelectronic device has become a key problem for further development. In this paper, we report one simple encapsulation method for organic optoelectronic devices with a parafilm, based on ternary polymer solar cells(PSCs). The power conversion efficiencies(PCE) of PSCs with and without encapsulation decrease from 2.93% to 2.17% and from 2.87% to 1.16% after 168-hours of degradation under an ambient environment, respectively. The stability of PSCs could be enhanced by encapsulation with a parafilm. The encapsulation method is a competitive choice for organic optoelectronic devices, owing to its low cost and compatibility with flexible devices.     

电极对CuPc/C60双层异质结有机太阳能电池光学性能的影响

采用传输矩阵法的光学模型以及MATLAB软件模拟了电极对CuPc/C₆₀双层异质结有机太阳能电池光学性能的影响。模拟结果表明:当把微腔结构引入到双层异质结电池时,对于入射电极,发现活性层的吸光率主要受其反射相移的影响而非其透射率,并且通过变化入射电极相移调节层到合适厚度可以使活性层吸光率相比于传统器件增加很多;而当把正负折射率交替的光子晶体引入到电池中作为背电极时,发现活性层的吸光率和背电极反射率、反射相移都有很大关系,在获得高反射率的同时可以通过调节背电极厚度从而使活性层在整个吸收光谱内的吸光率大于传统器件。     

Evanescent wave spectroscopy of methylene blue solutions at surfaces using a continuum generated by a nonlinear fiber

The way organic thin films properties are affected by molecular interactions at surfaces is an important research topic because thin molecular films constitute a model system for biological research and have applications ranging from light-emitting diodes and solar cells to chemical sensors. In this work, the formation of thin films of Methylene Blue in aqueous solution at a fused quartz surface was investigated with evanescent wave absorption spectroscopy, using a continuum spectrum generated in a non-linear fiber by short laser pulses.     

单线态分裂的超快光谱学研究

有机分子中的单线态分裂过程能将单个光激发的单线态激子转化成两个三线态激子. 借助此载流子倍增效应, 太阳能电池可以更有效地利用太阳光谱中的高能光子, 进而突破单结太阳能电池效率的理论极限. 因此, 单线态分裂备受关注. 本文回顾学术界对单线态分裂物理图像的认识以及争议, 结合课题组近年来的一些结果, 重点总结此领域中运用瞬态光谱学方法取得的实验进展, 讨论有关多激子中间暗态机理的不同观点, 并介绍单线态分裂材料的发展以及器件应用.     

Key parameters of two typical intercalation reactions to prepare hybrid inorganic-organic perovskite films

A star hybrid inorganic-organic perovskite material selected as an outstanding absorbing layer in solar cells benefits from multiple preparation techniques and excellent photoelectric characteristics. Among numerous synthetic processes,uniform, compact, and multi-stack perovskite thin films can be manufactured using vacuum deposition. During sequential vacuum deposition, the penetration ability of the organic molecules cannot be effectively controlled. In addition, the relationship between the thickness of the inorganic seeding layer and the organic molecule concentration for optimized devices using an evaporation-solution method is unclear. In this work, we prepared high-quality perovskite films by effectively controlling the penetration ability and chemical quantity of organic methyl ammonium iodide by monitoring the evaporation pressure and time. Thus, a device efficiency of over 15% was achieved with an all-vacuum prepared perovskite film. For the evaporation-solution method, we reacted different thicknesses of inorganic lead iodine with various concentrations of the organic molecule solution. The inorganic layer thickness and organic molecule concentration showed a linear relationship to achieve an optimum perovskite film, and an empirical formula was obtained. This work noted the key parameters of two intercalation reactions to prepare perovskite films, which paves a way to deliver a device that enables multi-layered structures, such as tandem solar cells.     

In_2O_3:Sn中间层改善B掺杂ZnO薄膜的性能及其应用研究

金属有机化学气相沉积(MOCVD)法生长的掺硼氧化锌(BZO)薄膜,具有天然的"类金字塔"绒面结构,作为硅基薄膜太阳电池的前电极具有良好的陷光效果.但直接获得的BZO薄膜表面形貌过于尖锐,影响后续硅基薄膜材料生长质量及太阳电池的光电转换效率.本文设计了以一层超薄In2O3:Sn(ITO)薄膜(～4 nm厚度)作为中间层的多层膜,并通过对顶层BZO薄膜的厚度调制,改善BZO薄膜的表面特性,薄膜结构为:glass/底层BZO/ITO/顶层BZO.合适厚度的顶层BZO薄膜有助于获得类似"菜花状"形貌特征,尖锐的表面趋于"柔和",而较厚的顶层BZO薄膜仍然保持"类金字塔状"结构."柔和"的BZO薄膜表面结构有助于提高后续生长薄膜电池的结晶质量.将获得的新型"三明治"结构多层膜应用于p-i-n型氢化微晶硅(μc-Si:H)薄膜太阳电池,相比传统的BZO薄膜,电池的量子效率QE在500—800 nm波长范围提高了～10%,并且电池的Jsc和Voc均有所提高.     

A multi-wall carbon nanotube–molecular semiconductor composite for bi-layer organic solar cells

A water-soluble composite of oxidised multi-wall carbon nanotubes and sulphonic acid sodium salt derivatised copper phthalocyanine for application in bi-layer organic solar cells is reported. Measurements of the topography of thin films of this novel material and of the valence electronic structure of its two components are used to rationalise the photovoltaic characteristics of a model organic heterojunction utilising the nanocomposite as the hole-extracting electrode and donor layer.     

Crystalline Si thin-film solar cells: a review

The present review summarizes the results of research efforts in the field of crystalline silicon thin-film solar cells on foreign substrates. The large number of competing approaches can be broadly classified according to the grain size of the crystalline Si films and the doping of the crystalline absorber. Currently, solar cells based on microcrystalline Si films on glass with an intrinsic or moderately doped absorber film achieve efficiencies around 10%, whereas thin-film cells fabricated from large-grained polycrystalline Si on high-temperature-resistant substrates have efficiencies in the range of 15%. The paper discusses the limitations of various approaches and describes recent developments in the area of thin, monocrystalline Si films that may open the way towards 20% efficient thin-film Si solar cells. Received: 1 March 1999 / Accepted: 28 March 1999 / Published online: 24 June 1999     

金属纳米颗粒对有机太阳能电池光吸收效率影响的研究

借助时域有限差分法,对几种常见金属纳米颗粒影响有机太阳能电池光吸收效率的因素及其内部物理机制进行了研究.首先对金属纳米颗粒激发局域表面等离子共振的场分布特点进行分析,对比其在电池不同功能层中对光吸收率的影响;其次基于米氏理论与电共振效应,得出金属纳米颗粒的结构参量对局域表面等离子共振位置及强度的影响规律,并以此进行优化设计.结果表明,具有高对称性形貌的金属纳米颗粒以小尺寸密堆积结构引入电池活性层,能够促进电池光吸收增强三倍以上.     

金属纳米颗粒对有机太阳能电池光吸收效率影响的研究

借助时域有限差分法,对几种常见金属纳米颗粒影响有机太阳能电池光吸收效率的因素及其内部物理机制进行了研究.首先对金属纳米颗粒激发局域表面等离子共振的场分布特点进行分析,对比其在电池不同功能层中对光吸收率的影响;其次基于米氏理论与电共振效应,得出金属纳米颗粒的结构参量对局域表面等离子共振位置及强度的影响规律,并以此进行优化设计.结果表明,具有高对称性形貌的金属纳米颗粒以小尺寸密堆积结构引入电池活性层,能够促进电池光吸收增强三倍以上.