结晶性有机半导体异质结器件

今天几乎所有重要的半导体器件的工作原理都与异质结和肖特基结有关,比较完整地理解和运用异质结和肖特基结是通过了长达半个世纪的持续努力.近20年有机异质结构已经被广泛的应用到有机电子器件中,包括有机发光二极管、有机光伏电池和有机场效应晶体管.然而,目前却缺少对有机异质结效应的认识.因此,完整认识有机异质结并运用它来发展有机半导体材料与器件是我们面临的机遇和挑战.本文首先阐述了我们对结晶性有机半导体异质结效应的理解,然后给出了有机异质结在半导体器件中的应用,重点介绍了我们近年来在运用有机异质结发展高功能电子器件方面的探索工作和初步认识.有机异质结在高性能场效应晶体管、改善金属有机接触和叠层器件中连接单元等方面均有所应用.有机异质结具有丰富的类型,充分利用有机异质结的特征,将为发展适合有机半导体材料、新功能器件和高级功能器件提供了新的视角和途径.     

基于膜厚与分子量优化策略实现高效近红外有机光探测器

利用基于[1,2,3]三唑并[4,5-f]异吲哚-5,7(2H,6H)-二酮(TzBI)共轭聚合物PTzBI-Cl为给体,非富勒烯小分子Y6DT为受体,制备基于倒装结构的有机本体异质结光探测器.基于高分子量聚合物PTzBI-Cl-H制备的器件比低分子量材料制备的器件具有更低的暗电流和更高的光探测性能.通过对PTzBI-...     

电极材料对NPB/Alq3有机电致发光器件性能的影响

采用不同材料作为有机电致发光器件(OELDs)的电极, 制备了基本结构为[阳极/NPB(40 nm)]/Alq3(50 nm)/阴极]的异质结双层器件, 并通过改变OELDs器件的阴极或阳极来研究电极材料对器件光电性能的影响. 研究结果表明, 各器件电流-电压(I-V)关系的基本特征与陷阱电荷限制电流(TCLC)机制的拟合情况相符. 由于有机材料本身能级的无序性以及载流子迁移率对温度和电场的依赖性, 不同电极的载流子注入能力与其功函数并无直接关系. 双层器件中由于空穴传输层的引入, 使得载流子复合区域位于有机层异质结界面处, 降低了金属阴极对激子的猝灭作用, 从而大大提高了器件性能. 此外, 金属电极OLEDs器件结构具有的微腔效应会导致发射光谱的位移和谱峰宽度变窄, 这表明通过对金属电极的表面改性和优化可使器件性能超过常规结构的器件.     

有机电致发光器件中载流子传输与复合的调控

在典型的多异质结器件ITO/NPB/CBP：Ir（ppy）3/Bphen/Alq3/LiF/Al的基础上,利用有机半导体掺杂技术,设计制备了单异质结-单发光层器件、单异质结-p-i-n结构器件、单异质结-双发光层器件及无异质结-混合主体结构器件,并对其光电性能进行了研究和比较.其中,单异质结-p-i-n结构器件的最大功率效率为32.1lm/W,是参考器件的3.1倍,寿命是参考器件的15倍.无异质结-混合主体结构器件的最大功率效率为37.2lm/W,是参考器件的3.5倍,其寿命是参考器件的46倍.研究结果表明,通过对载流子传输层和发光层的优化设计,构建电子、空穴传输平衡的载流子传输层和发光层,减少或取消异质结界面仍可以实现对载流子传输和复合的有效调控,从而使器件的发光效率和寿命同时得到提高.本研究将为高性能OLED的设计提供实验基础.     

可溶性窄带隙芴-噻吩共轭齐聚物的合成与表征

设计并合成了新型可溶性芴-噻吩共轭齐聚物FT6CE,对该化合物的热性质、光物理性质和电化学性质进行了详细表征.以FT6CE为给体,(6,6)-苯基-C61-丁酸甲酯(PC61BM)为受体,用溶液旋涂方法制备了体异质结太阳能电池器件,发现采用体积比为2∶1的氯仿/氯苯混合溶剂制备的器件性能最好,能量转换效率达到2.15%.     

用平衡相容性和相分离的新策略提高有机太阳电池效率

选择了两种具有不同末端基的非富勒烯受体分子3,9-双-[2-甲烯基-(3-1,1-甲烯丙二腈茚酮)-5,5,11,11-四-(4-己基苯基)]-噻吩[3,2-b]并噻吩引达省二噻吩(ITIC)和3,9-双-[2-甲烯基-(3-1,1-甲烯丙二腈-6,7-一氟茚酮)-5,5,11,11-四-(4-己基苯基)]-噻吩[3,2-b]并噻吩引达省二噻吩(IT-2F)作为第三组分，通过一步沉积(O-SD)和分步顺序沉积(T-SD)两种活性层构筑工艺,分别制备了常规的本体异质结(BHJ)和优化的准平面异质结(PPHJ)三元器件.研究发现,本体异质结薄膜中第三组分相容性的差异可以用来调控薄膜相分离形貌;其中,基于IT-2F的三元薄膜活性层相分离明显增大,器件效率由二元器件的12.02%下降至9.25%;而ITIC的三元薄膜相分离形貌无明显改变,器件效率略有提升.值得注意的是,通过T-SD方法均可以获得垂直梯度分布的异质结活性层薄膜,避免了相容性差异对薄膜形貌的影响,相应的准平面异质结器件获得了超过了13%的光电效率.本文工作表明,利用相容性差异以及顺序沉积工艺来调控活性层的相分离形貌是制备高性能有机...     

基于窄带系DPP类聚合物的高性能近红外有机光探测器件

采用窄带隙给体材料DPPDTT和富勒烯衍生物受体PCBM共混作为活性层,制备了具有高激子分离和电荷传输效率的近红外有机光探测器件,并进一步采用窄带隙受体Y6代替PCBM制备一种"双窄带隙吸收"的异质结结构,在近红外区域的吸收叠加有效地增强了器件光响应能力.最后,通过采用厚活性层、插入阻挡层以及制备倒置结构等方法,将器件...     

硒吩聚合物/寡聚物有机光电材料研究进展

主要从光电性能角度总结了近几年硒吩聚合物/寡聚物在有机太阳能电池(OSCs)、场效应晶体管(FETs)、发光二级管(LED)等方面的研究进展。目前,基于聚硒吩并[3,4-b]硒吩-苯并二硒吩(PSeB2)(polyselenopheno[3,4-b]selenophene-co-benzodiselenophene)本体异质结太阳能电池器件的能量转化效率最高,达6.87%;场效应晶体管方面,基于PSeDPP(P28)器件的空穴迁移率最高达1.62cm2.V-1.s-1。基于PFO-DDSTQ(一种硒吩芴基聚合物)的发光二级管,表现出目前基于硒吩化合物的最长波长发光器件,EL光谱峰值约860nm。通过对研究者的研究成果的总结发现,在有机光电器件的应用领域中硒吩聚合物/寡聚物是一种极具应用前景的材料。     

利用铁电薄膜研究体异质结型有机光伏器件的光电流极性

制备了铌镁酸铅-钛酸铅(PMN-PT)铁电薄膜,并通过紫外-可见(UV-Vis)透射光谱、X射线衍射(XRD)和原子力显微镜(AFM)对其进行了表征.为了研究体异质结型有机共混膜的光电流特性,制作了氧化铟锡(ITO)/PMN-PT/有机共混膜/铝(Al)的光伏器件,调制激光照射下外加偏压的极性和大小变化将直接改变瞬态光电流的极性和大小,从而可在实验上证明传统体异质结型有机光伏器件的光电流极性是由器件阴、阳电极的功函数差所导致的内建电场的方向决定.同时也提出了一种利用铁电薄膜来研究体异质结型有机光伏器件光电流特性的新方法.     

聚合物本体异质结型太阳能电池研究进展

聚合物本体异质结型太阳能电池是一种基于电子给体 /受体混合物薄膜的高效率有机光伏器件。文中介绍了近年来聚合物本体异质结型太阳能电池的最新研究进展 ,指出了目前存在的问题和今后的发展方向     

Theoretically Rational Designs of Transport Organic Semiconductors Based on Heteroacenes

A Marcus electron transfer theory coupled with an incoherent polaron hopping and charge diffusion model in combining with first‐principle quantum chemistry calculation was applied to investigating the effects of heteroatom on the intermolecular charge transfer rate for a series of heteroacene molecules. The influences of intermolecular packing and charge reorganization energy were discussed. It was found that the sulphur and nitrogen substituted heteroacenes were intrinsically hole‐transporting materials due to the reduced hole reorganization energy and the enhanced overlap between HOMOs. For the oxygen‐substituted heteroacene, it was found that both the electronic couplings and the reorganization energies for holes and electrons were comparative, indicating the application potential of ambipolar devices. Most interestingly, for the boron‐substituted heteroacenes, theoretical calculations predicted a promising electron‐transport material, which is rare for organic materials. These findings provide insights into rationally designing organic semiconductors with specific properties.     

Non-Condon电子转移速率理论与含时波包方法

随着电子转移理论在化学、材料科学、生物医学等领域的广泛应用,人们针对不同体系提出了多种电子转移理论模型。本文主要总结了近年来我们在non-Condon电子转移理论以及含时波包方法等方面的相关工作。首先阐述包含non-Condon效应的电子转移速率理论并用于二噻吩四硫富瓦烯有机半导体迁移率的计算。而后介绍了包含量子相干效应的含时波包方法,并初步用于研究二聚芴分子三三态能量转移过程。另外,本文还阐述了如何采用量子化学计算获得电子转移速率的结构参数。     

Intramolecular Energy Transfer in Dithienogermole Derivatives

Dithienogermole (DTG) has been applied as a useful building unit of optical/semiconducting materials for organic optoelectronic devices because of its extended conjugation, high chemical stability, and good emissive properties. Although DTG has two substituents on the Ge atom, the substituents have been limited to simple alkyl and aryl groups in previous work. In this work, to further uncover the new functionalities of this useful building unit, various π-conjugated groups were introduced on Ge of DTG. It was expected that the introduction of π-conjugated groups would give rise to efficient energy transfer between the substituents and the DTG core, which are in proximity and linked by a Ge atom. The thus-prepared DTG compounds with fluorene, terthiophene, and pyrene units on Ge possessed well-separated frontier orbitals on the substituents and the DTG core, as proved by the absorption spectra and DFT calculations. The substituted DTG derivatives showed clear emission only from the energy acceptor even though the energy donor was photoexcited. This indicated the highly efficient energy transfer in these compounds. We also prepared more π-extended compound DTGFl2-Ph with phenyl groups on the DTG thiophene rings. DTGFl2-Ph showed strong emission in the visible region with efficient energy transfer properties. These results clearly indicate the potential application of the present DTG system as optical functional materials.     

有机单晶场效应晶体管

有机单晶场效应晶体管的研究对于探索电子的本质特性具有十分重要的意义。近几年来，不管是在制备技术还是在器件性能的研究方面，有机单晶场效应晶体管均取得了很大的进步，并由此引起了社会的广泛关注，成为场效应晶体管领域的一个重要研究方向。本文主要介绍了有机单晶的生长方法、有机场效应器件的各种制备技术、器件的迁移率及其影响因素，并对有机单晶场效应晶体管的发展前景和面临的一些问题作了简要的讨论。     

有机单晶场效应晶体管

有机单晶场效应晶体管的研究对于探索电子的本质特性具有十分重要的意义。近几年来,不管是在制备技术还是在器件性能的研究方面,有机单晶场效应晶体管均取得了很大的进步,并由此引起了社会的广泛关注,成为场效应晶体管领域的一个重要研究方向。本文主要介绍了有机单晶的生长方法、有机场效应器件的各种制备技术、器件的迁移率及其影响因素,并对有机单晶场效应晶体管的发展前景和面临的一些问题作了简要的讨论。     

Conductive Metal-Organic Frameworks: Electronic Structure and Electrochemical Applications

Smarter and minimization of devices are consistently substantial to shape the energy landscape. Significant amounts of endeavours have come forward as promising steps to surmount this formidable challenge. It is undeniable that material scientists were contemplating smarter material beyond purely inorganic or organic materials. To our delight, metal-organic frameworks (MOFs), an inorganic-organic hybrid scaffold with unprecedented tunability and smart functionalities, have recently started their journey as an alternative. In this review, we focus on such propitious potential of MOFs that was untapped over a long time. We cover the synthetic strategies and (or) post-synthetic modifications towards the formation of conductive MOFs and their underlying concepts of charge transfer with structural aspects. We addressed theoretical calculations with the experimental outcomes and spectroelectrochemistry, which will trigger vigorous impetus about intrinsic electronic behaviour of the conductive frameworks. Finally, we discussed electrocatalysts and energy storage devices stemming from conductive MOFs to meet energy demand in the near future.     

Energy‐level alignment at metal–organic and organic–organic interfaces

This article reports on the electronic structure at interfaces found in organic semiconductor devices. The studied organic materials are C₆₀ and poly (para‐phenylenevinylene) (PPV)‐like oligomers, and the metals are polycrystalline Au and Ag. To measure the energy levels at these interfaces, ultraviolet photoelectron spectroscopy has been used. It is shown how the energy levels at interfaces deviate from the bulk. Furthermore, it is demonstrated that the vacuum levels do not align at the studied interfaces. The misalignment is caused by an electric field at the interface. Several effects are presented that influence the energy alignment at interfaces, such as screening effects, dipole layer formation, charge transfer, and chemical interaction. The combination of interfaces investigated here is similar to interfaces found in polymer light‐emitting diodes and organic bulk heterojunction photovoltaic devices. The result, the misalignment of the vacuum levels, is expected to influence charge‐transfer processes across these interfaces, possibly affecting the electrical characteristics of organic semiconductor devices that contain similar interfaces. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2549–2560, 2003     

卟啉－苝酰亚胺分子阵列的合成及应用进展

由于卟啉与苝酰亚胺基元之间存在高效的能量转移或电子转移过程, 卟啉-苝酰亚胺分子阵列表现出优良的光电性能, 在有机分子器件、有机太阳能电池和光收集材料等高新技术领域展示出广阔的应用前景. 综述了近十几年来卟啉-苝酰亚胺分子阵列的合成及应用研究进展, 并展望了其发展前景.     

有机自旋光电子学的基本过程

有机自旋光电子学的研究方向分为磁场效应和自旋注入两个方面.研究表明,外加低磁场能够显著改变非磁性有机半导体材料的光致发光、注入电流、电致发光和光电流.这称为有机半导体材料的磁场效应.近年来,非磁性有机半导体材料的磁场效应引起了广泛的关注和研究兴趣.首先,有机半导体材料的磁场效应是强有力的实验手段,用以研究有机电学、光学和光电器件中电荷传输和激发态中的有用和无用过程,为解决电荷传输和激发态过程中的瓶颈问题提供有效的实验手段,为实现磁-光-电多功能集成提供科学原理,尤其是磁场效应能够为提高能量转换效率、探测和传感光电子学器件的响应频谱范围和灵敏度提供新思路.同时利用磁电极,有机半导体材料和器件中自旋注入及其对电荷传输和激发态过程的调控可以用于发展新型功能化的自旋光电子学器件.本文综述并讨论了有机半导体材料和器件中的磁场效应和自旋注入的光电子学效应.     

Photoinduced energy transfer and charge transfer on squarylium cyanine dyes

A series of squarylium cyanine dyes (Sqs) were synthesized to explore their applications in functional devices.Preliminary investigation on the mechanism involved in these devices was carried out.Spectroscopic behavior of Sqs with porphyrin (P),8-hydroxyquinolium aluminum (Alq) and ruthenium bipyridyl complex (Ru(bipy)) in solution,in film and on nanocrystalline TiO2 was investigated,respectively.A mechanism including photoinduced energy transfer and charge transfer processes was suggested in the corresponding practical devices.By means of doping,a red organic electroluminescent device (ELD) using Sq-doped Alq as the emission layer (EML) has been developed,and the total light to electricity efficiency of nanocrystalline TiO2 electrode based on using Sq-doped Ru(bipy) as photosensitizer has been improved greatly in the whole visible region,particularly in the red area above 600 nm.