器件结构对聚合物太阳能电池内部光电强分布的影响

针对以电子给体聚(3-己基噻吩)(P3HT)和电子受体6,6-苯基-C61-丁酸甲酯(PCBM)共混薄膜为活性层的本体异质结聚合物太阳能电池,根据光学干涉效应和转移矩阵方法建立了非相干光吸收理论模型,研究了电极修饰层、活性层和阴极的厚度对电池内部光电场分布和活性层内部光电场强度的影响.结果表明:各功能层厚度对电池内部光电场分布和活性层光电场强度具有不同程度的影响,其中活性层和电极修饰层厚度的影响较大,而阴极厚度的影响较小;引入合适厚度的电极修饰层有利于增加活性层内部的光电场强度,提高太阳能电池的能量转换效率,改善器件的光伏性能.     

纽扣状TiO_2纳米球在钙钛矿太阳能电池中的应用

将具有(001)高能面的纽扣状二氧化钛纳米球添加到无空穴传输材料的钙钛矿太阳能电池多孔骨架层材料中,能改变骨架层的形态结构,有利于形成高覆盖率的钙钛矿吸光层;同时纳米球可以提高光生载流子的分离和输运效率,有利于获得更高的开路电压和填充因子.优化纳米球与二氧化钛颗粒的比例,在AM1.5的标准光强下,钙钛矿太阳能电池的光电转换效率由9.42%提升至11.5%.     

基于多功能层TiO2薄膜增强染料敏化太阳能电池性能?

利用粒径为20和200nm TiO2在导电玻璃表面制备光阳极的光透明层薄膜、混合层薄膜以及散射层薄膜,通过有效地调整3种薄膜结构进而制备了染料敏化太阳能电池.研究表明,多功能层TiO2膜结构大幅度地提升了光电流,而且电子在多功能层TiO2膜内的界面传输阻抗较低.将3种薄膜有效结合并控制其厚度,可以有效地提高染料敏化太阳能电池的性能,在AM1.5,光强度为100 mW·cm-2的条件下,染料敏化太阳能电池光电转化效率可以提升至5.29%,电流密度达到11.7mA·cm-2.     

多光学间隔层结构的聚合物太阳能电池

为提高聚合物太阳能电池中有源层的光吸收,提出了一种新型结构的器件———具有多光学间隔层结构的 聚合物太阳能电池,该结构通过调节多光学间隔层折射率的分布方式,调节有源层内光电场的分布,使有源层 对入射光得到充分吸收,进而优化器件性能。采用传输矩阵法对这种多光学间隔层聚合物太阳能电池进行了 光学模拟,探索了多光学间隔层折射率的分布方式对倒置结构聚合物太阳能电池器件有源层光电场的分布和 短路电流密度( Jsc) 的影响。模拟选取的多光学间隔层是通过在ITO( Indium Tin Oxide) 玻璃衬底上依次旋涂未 掺杂ZnO 和掺杂浓度分别为0． 002 5 mol /L,0． 005 mol /L,0． 01 mol /L 的铯掺杂氧化锌( CZO: Cs doped Zinc Oxide) 薄膜制备而成的。模拟结果显示,采用从上到下铯掺杂浓度依次增加的多光学间隔层结构能有效提高 器件有源层对入射光的光吸收和短路电流密度。     

小分子浴铜灵作为缓冲层的钙钛矿太阳能电池性能研究

以有机小分子浴铜灵(BCP)作为缓冲层,引入钙钛矿太阳能电池的电子传输层与阴极之间,研究其对钙钛矿太阳能电池的能量转换效率及载流子的传输特性的影响。结果表明,相对于无BCP缓冲层的钙钛矿太阳能电池,器件的最高能量转换效率由9.67%提高到13.06%。BCP缓冲层的引入,降低了电荷传递电阻,提高了阴极的电子收集能力,可增强钙钛矿太阳能电池的光伏性能。     

光电催化CO2还原技术研究进展

以用于光电催化CO₂还原的铜基光电阴极为研究对象．首先,分析了光催化、电催化和光电催化的基本原理,并总结了光电催化系统的主要优点．然后,从改善吸光能力、抑制光腐蚀、促进载流子分离、优化界面反应等方面对增强铜基光电阴极性能的策略进行了分析．通过对催化剂的形貌进行调控、负载吸光半导体和元素参杂可以提高吸光能力;通过表面包裹保护膜,可以有效抑制光腐蚀;通过表面空穴工程或引入石墨烯/还原氧化石墨烯、金属有机骨架和碳纳米管等材料,能够有效提高载流子分离率和传输效率;通过增加活性位点、引入局域等离子体效应和提高CO₂吸附性能,能够优化界面反应．最后,分析了连续流动反应器设计的最新研究进展,并对铜基光电阴极开发需解决的技术问题进行了展望．     

新型二维碳材料net-Y光学性质的第一性原理研究

采用基于密度泛函理论的第一性原理研究方法,对新型二维碳材料(单层net-Y)的光学性质进行了研究.基于反射、吸收、折射和介电函数等数据分析了单层net-Y的光学性质.计算结果表明:在E_x、E_y和E_z这3个方向极化下,单层net-Y的复介电函数、复折射函数、吸收系数等光学性质表现出显著的各向异性.光学性质研究表明:该材料在整体光区具有极不敏感的光反射性质,且在紫外光区具有高吸光系数以及在能量频率为10.0 eV处具有极低的消光系数.此外, 与其他波段的光相比,在E_y极化下单层net-Y对黄光有更强的光折射响应.     

溶剂蒸汽退火对钙钛矿薄膜形貌和电池性能的影响

针对钙钛矿太阳能电池钙钛矿吸光层在溶液法旋涂中出现的薄膜旋涂不均匀、针孔、结晶性不好的现象,采用溶剂蒸汽退火和直接接触嵌入法(DCIP)结合的方法制备了结晶均匀并且晶体比较大的钙钛矿活性层。结果表明,当二甲基亚砜(DMSO)的加入量为15μL时,钙钛矿的平均粒径由大约300nm增加到1 200nm,对应电池的光电转化效率也由11%升高到14.33%.由此提高了钙钛矿太阳能电池的性能,并为制作面积较大的钙钛矿太阳能电池提供了依据和方法。     

新一代无源光网络的研究

对新一代无源光网络EPON和GPON的协议层次进行了比较,指出两者的主要差异在于采用了不同的第二层技术,即EPON采用以太网技术,GPON采用高效的传输汇聚层技术.并对EPON和GPON性能参数进行了分析,比较了两者在基本技术要求、传输复用方式、帧结构、承载业务、管理能力和生存性等方面的不同,及其各自的特点和优劣.最后,提出了通过两者的混合组网而达到优势互补,以实现“全业务”的接入.     

有机-无机钙钛矿晶体生长调控研究进展

钙钛矿太阳能电池是近5年太阳能转化利用领域的研究热点,受到国内外研究者的广泛关注.ABX3钙钛矿不但具有快速传递空穴和电子的能力,而且具有强而宽的可见光吸收性能.介观和平面结构钙钛矿薄膜电池是并重发展的钙钛矿太阳能电池.其小于1!m钙钛矿光活性层使得器件对钙钛矿层的结晶度和成膜性有着较高的要求.通过控制钙钛矿的结晶方式和质量来提高膜的性能就成为了提高电池光电转化效率的重要方式之一.第一部分综述了各种制备条件下利用一步法和两步法合成ABX3太阳能电池钙钛矿薄膜.进一步通过提高钙钛矿材料的晶体质量,将钙钛矿太阳能电池的光电转化效率从3.8%提高到20%.此外,和钙钛矿薄膜相比,钙钛矿大晶体不但具有较长的载流子传输路径,而且结构更加完整,更有利排除其他因素的干扰,增进对钙钛矿结构的深入解析.因此第二部分重点介绍了钙钛矿单晶的性能和制备方法,并对其在太阳能电池和光电探测器中的应用做了初步展望.     

Enhanced power conversion efficiency in bulk heterojunction polymer solar cells through dual-interface morphology modification

Efficient bulk heterojunction (BHJ) polymer solar cells with a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) hole transfer layer (HTL) were fabricated via controlling the spin coating speed of the HTL solution on a particular fluorinated tin oxide substrates of a high roughness. It shows that the functions of the photovoltaic devices increase with the increase of the HTL surface roughness. Then, an imprinting technique was employed to transfer a suitable pattern of nanostructure arrays to the surface of active layers. At the optimized spin coating speed, the photovoltaic devices exhibited a 28.4% increase in efficiency after this imprinting treatment compared with that of nonimprinted photovoltaic devices. It is mainly attributed to the achievement of high interface areas between active layers and electrodes, which not only increases optical absorption by scattering but also facilitates charge carrier collection.     

Doping-free carbon nanotube optoelectronic devices

Semiconducting carbon nanotubes (CNTs) possess outstanding electrical and optical properties because of their special one-dimensional (1D) structure. CNTs are direct bandgap materials, which makes them ideal for use in optoelectronic devices, e.g. light emitters and light detectors. Excitons determine their light absorption and light emission processes due to the strong Coulomb interactions between electrons and holes in CNTs. In this paper, we review recent progress in CNT photodetectors, photovoltaic devices and light emitters. In particular, we focus on the doping-free CNT optoelectronic devices developed by our group in recent years.     

ZnO/Cs2CO3双电子传输层有机太阳能电池

有机太阳能电池的异质结界面是影响其性能的一个重要因素.以氧化锌/碳酸铯作为双电子传输层,改善电子传输层与活性层的界面接触并提高电子传输能力.利用溶胶-凝胶法制备OSCs器件,通过优化的双电子传输层,使基于PTB7-Th:PC₇₁BM的OSCs器件的最高效率达到了8.08%,其相较于ZnO电子传输层器件提高了10.68%.实验表明,由于ZnO/Cs₂CO₃ ETLs具有最佳的表面形貌和光吸收,其填充因子、短路电流密度和电子迁移率都显著提升.这种ZnO/Cs₂CO₃双电子传输层为OSCs性能改善提供了新的思路.     

不同溶剂溶解聚合物光伏特性的研究

采用聚3-己基噻吩（P3HT）溶于不同溶剂作为光敏层制备光伏器件,器件结构为：ITO/PEDOT：PSS/P3HT/Al.我们分析了聚3-己基噻吩（P3HT）溶于不同溶剂制成的光敏层薄膜,并对光敏层薄膜的形貌通过原子力显微镜（AFM）进行了表征.研究发现,P3HT溶于氯苯的薄膜形貌最优,光伏特性最好,短路电流、开路电压都比溶于氯仿和二甲苯的高.     

碳纳米管光伏器件的研究进展

碳纳米管（CNT）具有优异的电学特性和独特的一维纳米结构，是制作光伏器件的良好材料.文中介绍了单根/多根CNT光伏器件、CNT薄膜光伏器件、CNT 有机光伏器件、杯状叠层CNT光伏器件等典型CNT光伏器件，并阐述了这些CNT光伏器件的结构及特性，分析了CNT在器件中的作用.     

A photovoltaic device structure based on internal electron emission

There has been an active search for cost-effective photovoltaic devices since the development of the first solar cells in the 1950s (refs 1-3). In conventional solid-state solar cells, electron-hole pairs are created by light absorption in a semiconductor, with charge separation and collection accomplished under the influence of electric fields within the semiconductor. Here we report a multilayer photovoltaic device structure in which photon absorption instead occurs in photoreceptors deposited on the surface of an ultrathin metal-semiconductor junction Schottky diode. Photoexcited electrons are transferred to the metal and travel ballistically to--and over--the Schottky barrier, so providing the photocurrent output. Low-energy (approximately 1 eV) electrons have surprisingly long ballistic path lengths in noble metals, allowing a large fraction of the electrons to be collected. Unlike conventional cells, the semiconductor in this device serves only for majority charge transport and separation. Devices fabricated using a fluorescein photoreceptor on an Au/TiO2/Ti multilayer structure had typical open-circuit photovoltages of 600-800 mV and short-circuit photocurrents of 10-18 micro A cm(-2) under 100 mW cm(-2) visible band illumination: the internal quantum efficiency (electrons measured per photon absorbed) was 10 per cent. This alternative approach to photovoltaic energy conversion might provide the basis for durable low-cost solar cells using a variety of materials.     

Alternate redox electrolytes in dye-sensitized solar cells

Dye-sensitized mesoscopic solar cell(DSC) has been intensively investigated as a promising photovoltaic cell.Redox electrolyte is important to determine the photovoltaic(PV) performance of the DSC devices,which has become the focus of this topic.In this contribution,recent advances in understanding and controlling of various redox couples are reviewed.Specially,we extend our discussion on the trends that enable iodide-free redox couples to be controllable and feasible for applications in the DSC with promising features.     

受光区具有薄n层结构的光控晶闸管的研究

本文研讨了具有薄n层结构的受光区,对提高光控晶闸管的光触发灵敏度的作用及触发灵敏度与dV/dt耐量间的协调关系,结果表明,这种结构可使其具有较高的触发灵敏度,可较好的协调灵敏度与dV/dt耐量间的关系。并利用这一结构,研制出了高灵敏度的500A,2000V直接光触发晶闸管。     

基于磁光材料的磁可调石墨烯多带吸收特性

为了改善石墨烯的吸收性能,基于石墨烯的磁光效应,提出了一种采用磁性材料构成的光子晶体异质结构。该光学结构可使石墨烯实现多带吸收。吸收带的数目可通过改变光子晶体的周期数来调节。利用4×4传输矩阵法数值研究了该光子晶体异质结构的相关参数对石墨烯吸收率的影响。结果表明:石墨烯的吸收特性表现出一定的磁圆二色性。但通过调节费米能量,在外磁场的作用,左旋圆偏振光和右旋圆偏振光均可具有较高的吸收率。研究结果为偏振光学领域石墨烯基新型光子学器件的设计制作提供了理论依据。     

Optical nano-imaging of gate-tunable graphene plasmons

The ability to manipulate optical fields and the energy flow of light is central to modern information and communication technologies, as well as quantum information processing schemes. However, because photons do not possess charge, a way of controlling them efficiently by electrical means has so far proved elusive. A promising way to achieve electric control of light could be through plasmon polaritons—coupled excitations of photons and charge carriers—in graphene. In this two-dimensional sheet of carbon atoms, it is expected that plasmon polaritons and their associated optical fields can readily be tuned electrically by varying the graphene carrier density. Although evidence of optical graphene plasmon resonances has recently been obtained spectroscopically, no experiments so far have directly resolved propagating plasmons in real space. Here we launch and detect propagating optical plasmons in tapered graphene nanostructures using near-field scattering microscopy with infrared excitation light. We provide real-space images of plasmon fields, and find that the extracted plasmon wavelength is very short—more than 40 times smaller than the wavelength of illumination. We exploit this strong optical field confinement to turn a graphene nanostructure into a tunable resonant plasmonic cavity with extremely small mode volume. The cavity resonance is controlled in situ by gating the graphene, and in particular, complete switching on and off of the plasmon modes is demonstrated, thus paving the way towards graphene-based optical transistors. This successful alliance between nanoelectronics and nano-optics enables the development of active subwavelength-scale optics and a plethora of nano-optoelectronic devices and functionalities, such as tunable metamaterials, nanoscale optical processing, and strongly enhanced light–matter interactions for quantum devices and biosensing applications.