内嵌金属富勒烯Gd@C_(82)在Cu(111)和Pt(111)表面吸附结构的STM研究CSCD

利用扫描隧道显微镜(STM)研究分析了内嵌金属富勒烯分子Gd@C82在Cu(111)和Pt(111)上的低温(200～250 K)生长方式和吸附结构。不同强弱的分子-衬底间相互作用导致Gd@C82在Cu(111)和Pt(111)上的生长方式有很大区别。经过热处理后,Gd@C82分子诱导Cu(111)衬底发生重构,而在Pt(111)上未发现此现象。两种金属衬底不同的晶格常数和电子性质导致退火后的分子自组装结构也不一样:Gd@C82在Cu(111)上形成等价的两种吸附结构,即(√19×√19)R23.4°和(√19×√19)R36.6°;分子在Pt(111)上形成一种与〈110〉方向一致的密堆积结构。     

半金属表面上酞菁锰分子的转动态研究

利用低温STM研究了半金属Bi(111)表面上单个酞菁锰分子的转动态。通过高分辨STM图发现,在液氮温度(77K)下单个酞菁锰分子呈六角形。利用STM操纵技术实现了对单个酞菁锰分子的制动,并通过对单分子的高低起伏和吸附构型分析,确定分子在Bi(111)表面做非连续的中心转动。这种单分子转动是三种相对稳定的吸附构型交替变化的结果。结合I-t谱技术,进一步验证了这三种分子吸附构型的存在;并利用近似统计分析方法得到三种吸附构型各自出现的概率以及其相对能量。     

分子取向的高分辨率扫描隧道显微术

本文介绍了一种借助于扫描隧道显微镜的空间高分辨能力探测单个分子取向的方法.利用这种方法,我们研究了以下四种体系中的分子取向二维C 60分子阵列;C 60(111)多层膜表面;吸附在Si(111) (7×7)表面的C 60单分子;Au(111)表面的硫醇自组装单分子层膜.结合局域密度近似方法理论计算,我们确定了以上体系中的分子取向.     

C60单晶膜生长与衬底表面结构相关性研究

本文讨论了气相外延Ｃ＿（６０）薄膜与层状衬底表面结构是否相关的两种观点。根据对现有的实验结果分析，我们认为Ｃ＿（６０）单晶膜薄的生长与层状衬底表面结构相关，不同的表面结构与Ｃ＿（６０）分子的相互作用是不同的，从而影响生长膜的单晶完整性。     

超高真空蒸发沉积酞菁铜薄膜的X光电子谱研究

在ＸＰＳ分析室内利用超高真空蒸发方法在单晶硅衬底上沉积酞菁铜薄膜,并利用Ｘ光电子谱（ＸＰＳ）作原位分析,研究酞菁铜薄膜的沉积规律,并讨论了不同条件下酞菁铜配合物分子组成及结构的变化。结果发现利用超高真空沉积方法得到酞菁铜为近化学计量,随着蒸发温度的升高,分子中Ｃｕ原子的含量逐渐减少,Ｎ原子的含理逐渐升高,苯环上的碳原子与类朴啉环上的碳原子的比例逐渐减少,这与酞菁铜分子中各原子的价键状态、酞菁铜分子     

自组装法制备Au纳米结构衬底及其表面增强荧光效应研究

采用自组装方法,在(APS)分子修饰后的玻璃衬底 表面,制备得 到Au纳米结构衬底。采取激光光谱学方法,研究所制备衬底对沉积其表面的Rhodamine 6G(R h6G) 分子的荧光辐射增强效应。实验发现,利用自组装方法制备的Au纳米结构衬底具有较强的荧 光增 强特性。理论分析表明,制备的Au纳米结构在外光场激发下,所形成的强局部电磁场分布 能够有效提升探针分子的电子跃迁速率,从而实现增强荧光效应。     

C_(90)分子单层膜在Au(111)表面的STM研究

在超高真空中使用热蒸发方法,在Au(111)表面上制备了C90分子的分子单层膜,并利用超高真空低温扫描隧道显微镜在120 K温度下对其结构进行研究。观察到C90分子在Au(111)表面上先是沿着台阶边缘生长,分子铺满一层后,会在薄膜上形成岛状结构。本文对岛状结构进行了原位高分辨表征,观察到C90分子在正偏压和负偏压下的几种不同形貌,并给出了各种形貌所对应的C90分子构型。     

以金属为缓冲层在Si(111)上分子束外延GaN及其表征

用电子束蒸发方法在Si(111)衬底上蒸发了Au/Cr和Au/Ti/Al/Ti 两种金属缓冲层,然后在金属缓冲层上用气源分子束外延(GSMBE)生长GaN. 两种缓冲层的表面都比较平整和均匀,都是具有Au(111)面择优取向的立方相Au层. 在Au/Cr/Si(111)上MBE生长的GaN,生长结束后出现剥离. 在Au/Ti/Al/Ti/Si(111)上无AlN缓冲层直接生长GaN,得到的是多晶GaN;先在800℃生长一层AlN缓冲层,然后在710℃生长GaN,得到的是沿GaN(0001)面择优取向的六方相GaN. 将Au/Ti/Al/Ti/Si(111)在800℃下退火20min,金属层收缩为网状结构,并且成为多晶,不再具有Au(111)方向择优取向.     

Au(111)表面Dy@C82分子单层膜的STM研究

利用超高真空扫描隧道显微镜(UHV-STM),在低温(78K)下研究了不同覆盖度下Dy@C82(Ⅰ)膜在Au(111)表面的生长和结构.Dy@C82分子首先吸附于金台阶,进而延伸至金台面上形成紧密排列的一维分子链或二维分子岛.高分辨STM图像显示ZDy@C82分子具有多种不同的内部结构,表明Dy@C82分子在金表面的取向是无序的.     

钴酞菁分子结中电子输运性质的理论研究

利用半经验Extended Hueckel分子轨道方法和格林函数方法来研究钴酞菁(CoPc)分子结的电子输运性质。计算结果表明分子结(器件)电子输运性质对分子本身的电子结构、电极不同晶向表面、分子与电极间耦合强度、其界面的几何构型，对电极表面接触分子的末端原子的种类等诸多方面都有不同程度的依赖关系。对于CoPc这类弱耦合分子结而言，可以通过测量其I-V曲线来研究分子本身的电子结构。本文的理论方法不仅可以用来描述分子器件的电子输运行为，还能用来研究扫描探针显微镜体系的伏安特性和扫描隧道谱。     

Binary Molecular Layers of C60 and Copper Phthalocyanine on Au(111): Self‐Organized Nanostructuring

The binary molecular system of C₆₀ and copper phthalocyanine(CuPc) molecules has been investigated by scanning tunneling microscopy (STM) at room temperature and at 50 K. As substrate Au(111) was chosen. When C₆₀ and CuPc molecules are sequentially deposited, it is found that well‐ordered domains of both molecules may coexist simultaneously. Hence hexagonal ordering of C₆₀ and quadratic ordering of CuPc is observed side by side but no ordered mixed layer of both molecules or heteroepitaxy from one molecule on the other is found. Instead the boundaries of the CuPc domains are often decorated by C₆₀ molecules and for a particular choice of parameters, with regard to the film preparation, individual CuPc molecules may adsorb on top of a C₆₀ layer. The interaction with the underlying C₆₀ layer permits the molecules to perform a localized, hindered rotation. At room temperature the hopping frequency is so high that only the time average of the rotation is seen by STM while at 50 K the rotation is frozen and the CuPc molecule is trapped in one definite position.     

Small π-conjugated organic molecules based transistor and inverter with Cu electrodes

In absence of metallurgical Ohmic contacts in organic semiconductors, the relative position of metal work function with respect to highest occupied molecular orbital (HOMO) or lowest unoccupied molecular orbital (LUMO) decides whether a metal electrode is Ohmic or non-Ohmic. Here we report that Cu whose work function is close to HOMO of the small π-conjugated organic molecules: pentacene and copper phthalocyanine (CuPc), can be used to achieve high performance of transistors and inverters. Fermi level is pinned at metal/copper hexadecafluoro phthalocyanine (F₁₆CuPc) interface resulting the barrier for carrier injection from metal to F₁₆CuPc independent of metal work functions. We have fabricated organic field effect transistors and inverters based on pentacene, CuPc and F₁₆CuPc with Cu and Au electrodes and observed that the performance of the devices with Cu electrodes are comparable to the devices with Au electrodes.     

(Organic) Switching phenomenon in lateral structures: Tuning by gate voltage

We have fabricated devices based on copper phthalocyanine (CuPc) that exhibited electrical bistability and switching phenomenon. Apart from sandwiched structures, coplanar (lateral) electrodes or field-effect transistor structures have also been characterized. The observation of switching and memory phenomenon in lateral structures with Au/Au electrode combination primarily rules out (1) migration of metal ions into the organic materials, (2) metal filament formation through a redox-driven process, and (3) electroreduction of the molecules as possible mechanisms of electrical bistability in CuPc. The existence two conducting state and bistability have been explained in terms of trapping and detrapping of carriers in the molecular layer. Furthermore, the lateral structures show possibilities to tune switching processes through the bias of the base (gate) electrode.     

C90分子单层膜在Au(111)表面的STM研究

在超高真空中使用热蒸发方法,在Au(111)表面上制备了C90分子的分子单层膜,并利用超高真空低温扫描隧道显微镜在120 K温度下对其结构进行研究.观察到C90分子在Au(111)表面上先是沿着台阶边缘生长,分子铺满一层后,会在薄膜上形成岛状结构.本文对岛状结构进行了原位高分辨表征,观察到C90分子在正偏压和负偏压下的...     

酞菁铜有机静电感应三极管动作特性研究

介绍了由有机半导体材料酞菁铜制作的具有Au/CuPc/Al/CuPc/Au三明治结构的肖特基型栅极有机静电感应三极管.根据对该三极管测试,采用适当的数学工具,对其参数进行计算.通过Ⅰ-Ⅴ方程的拟合,对其动作特性进行了研究.通过对小信号等效电路模型的仿真计算,得出其截止频率,并提出了改善其动作特性的途径.     

Surface‐Transfer Doping of Organic Semiconductors Using Functionalized Self‐Assembled Monolayers

Controlling charge doping in organic semiconductors represents one of the key challenges in organic electronics that needs to be solved in order to optimize charge transport in organic devices. Charge transfer or charge separation at the molecule/substrate interface can be used to dope the semiconductor (substrate) surface or the active molecular layers close to the interface, and this process is referred to as surface‐transfer doping. By modifying the Au(111) substrate with self‐assembled monolayers (SAMs) of aromatic thiols with strong electron‐withdrawing trifluoromethyl (CF₃) functional groups, significant electron transfer from the active organic layers (copper(II) phthalocyanine; CuPc) to the underlying CF₃‐SAM near the interface is clearly observed by synchrotron photoemission spectroscopy. The electron transfer at the CuPc/CF₃‐SAM interface leads to an electron accumulation layer in CF₃‐SAM and a depletion layer in CuPc, thereby achieving p‐type doping of the CuPc layers close to the interface. In contrast, methyl (CH₃)‐terminated SAMs do not display significant electron transfer behavior at the CuPc/CH₃‐SAM interface, suggesting that these effects can be generalized to other organic‐SAM interfaces. Angular‐dependent near‐edge X‐ray absorption fine structure (NEXAFS) measurements reveal that CuPc molecules adopt a standing‐up configuration on both SAMs, suggesting that interface charge transfer has a negligible effect on the molecular orientation of CuPc on various SAMs.     

有机半导体薄膜三极管的研制

采用真空蒸镀法和有机半导体材料酞菁铜,制作Au/CuPc/Al/ CuPc/Au三明治结构的肖特基型栅极有机静电感应三极管.该三极管导电沟道垂直于CuPc薄膜,与采用MOSFET结构的有机薄膜三极管相比导电沟道大幅缩短,有利于克服有机半导体电学性能的缺点.实验结果表明,该三极管驱动电压低,呈不饱和电流-电压特性.其工作特性依赖于栅极电压和梳状铝电极的结构.通过合理设计、制作梳状铝电极,获得了良好的三极管静态、动态特性.     

Electrical characterization of the organic semiconductor Ag/CuPc/Au Schottky diode

This paper reports on the fabrication and investigation of a surface-type organic semiconductor copper phthalocyanine（CuPc） based diode.A thin film of CuPc of thickness 100 nm was thermally sublimed onto a glass substrate with preliminary deposited metallic electrodes to form a surface-type Ag/CuPc/Au Schottky diode.The current-voltage characteristics were measured at room temperature under dark conditions.The barrier height was calculated as 1.05 eV.The values of mobility and conductivity was found to be 1.74×10^-9 cm²/（V·s） and 5.5×10^-6Ω^-1·cm^-1,respectively.At low voltages the device showed ohmic conduction and the space charge limited current conduction mechanisms were dominated at higher voltages.     

CuPc/C60 bulk heterojunction photovoltaic cells with evidence of phase segregation

This work presents organic photovoltaic (OPV) device study based on cupper phthalocyanine (CuPc) and fullerene (C60) bulk heterojunction (BHJ) structure. By varying blend composition, the optimized performances were obtained in 75%-CuPc containing devices with anode buffer of either CuPc or HPCzI (1,3,4,5,6,7-hexaphenyl-2-{3′-(9-ethylcarbazolyl)}-isoindole). It was discovered by scanning electron microscopy that 75%-CuPc containing film possessed phase separation, which is beneficial to charge transport via percolation process. Additionally, electronic absorption measurement and hole only device study showed that, depending on the mixing ratio, the absorption and the hole transport ability were different. The blend film containing 75% CuPc had the largest integrated absorption with the most CuPc dimmer aggregate and the least C60 aggregate. Moreover, the 75% CuPc blend film also possessed the highest hole transport ability. Thus, the best performance of the 75% CuPc BHJ device is mainly attributed to its good carrier transport originating from phase segregation. The present work highlights the phase separation in CuPc:C60 mixing film with optimized ratio, as well as its corresponding electronic absorption and carrier transport properties, which are essential for OPV device performance. Hence, insights are inferred for further engineering of BHJ OPV devices based on small molecules.