C60场效应晶体管的制备及修饰层对器件性能影响的研究

以重掺杂Si片作为衬底,SiOe／聚甲基丙烯酸甲酯（PMMA）为双栅绝缘层,C60为有源层,制备了不同修饰层的有机场效应晶体管（OFETs）;研究了不同修饰层的器件对于场效应性能的影响。实验表明,与未加修饰层的器件相比,经过修饰的器件性能有一定的提高,其中Alqa／LiF双修饰层器件的场效应迁移率达到最大,为1．6×1...     

基于插入WO3缓冲层并五苯有机场效应晶体管性能的研究

The pentacene-based organic field effect transistor （OFET） with a thin transition metal oxide （WO3） layer between pentacene and metal （AI） source/drain electrodes was fabricated. Compared with conventional OFET with only metal AI source/drain electrodes, the introduction of the WO3 buffer layer leads to the device performance enhancement. The effective field-effect mobility and threshold voltage are improved to 1.90 em2/（V.s） and 13 V, respectively. The performance improvements are attributed to the decrease of the interface energy barrier and the contact resistance. The results indicate that it is an effective approach to improve the OFET performance by using a WO3 buffer layer.     

聚合物栅绝缘层厚度对并五苯有机场效应管性能的影响

采用不同厚度的聚甲基丙烯酸甲酯(PMMA)作为栅绝缘层,制备了并五苯有机场效应晶体管(OFET)。测量了不同厚度的PMMA的介电特性,并详细分析了栅绝缘层厚度对器件性能的影响。其中,采用260nm厚的PMMA栅绝缘层的OFET具有比采用其它厚度的器件更优越的性能,其场效应迁移率、阈值电压与开关电流比分别达到3.39×10-3 cm2/Vs、-19V和103。     

8-羟基喹啉锂材料及器件特性的研究

阐述了蓝光材料Liq的合成及其提纯方法,并用Liq作为发光材料制备了蓝色有机发光器件,研究了CuPe对该器件特性的影响.结果表明,CuPe的加入降低了空穴载流子的注入势垒,有利于提高空穴注入能力,因而提高了器件的亮度和发光效率.在电压为16 V时,没有缓冲层的器件效率为0.363 cd/A,有缓冲层的器件效率为0.731 cd/A.     

阴极修饰层对ZnPc/C60有机太阳能电池性能的影响

研究了ZnPc/C60有机小分子太阳能电池阴极界面的修饰,采用LiF、Alq3和ZnPc作为修饰材料,分析不同修饰材料对器件性能和稳定性的影响。研究结果表明,引入适当厚度的修饰层不仅可以提高器件的性能,而且可以提高器件的稳定性。不同修饰材料表现出了不同的优势,用LiF修饰的器件填充因子提高了44%,Alq3修饰的器件转换效率提高了5倍,ZnPc修饰的器件开路电压最高并表现出良好的稳定性。最后,对相关机理进行了讨论。     

并五苯钝化层增强C60有机场效应晶体管性能的研究

We investigated the properties of C₆₀-based organic field-enect transistors（OFETs）（?） a pentacene passivation layer inserted between the C₆₀ active layer and the gate dielectric.After modification of the pentacene passivation layer,the performance of the devices was considerably improved compared to C₆₀-based OFETs with only a PMMA dielectric.The peak field-effect mobility was up to 1.01 cm²/（V·s） and the on/off ratio shifted to 10⁴.This result indicates that using a pentacene passivation layer is an effective way to improve the performance of N-type OFETs.     

栅缓冲层对4H碳化硅肖特基势垒场效应晶体管性能的影响

通过在栅极和沟道层间插入一层低掺杂的缓冲层研究了其对肖特基势垒场效应晶体管性能的影响。通过求解一维和二维泊松方程,得到了电流和小信号参数与缓冲层厚度和浓度的依赖关系。当缓冲层厚度为0.15μm时,计算了器件的直流和交流特性;同时仿真了器件的击穿特性。结果表明,电流随缓冲层厚度增加;击穿电压由125V增加到160V;截止频率由20GHz增加到27GHz。     

InyAl1-yAs线性渐变缓冲层对InP基HEMT材料性能的影响

采用气体源分子束外延（GSMBE）技术,研究了InP衬底上In_yAl_1-yAs线性渐变缓冲层对In_0.66Ga_0.34As/In_yAl_1-yAs高迁移率晶体管（HEMT）材料特性影响。研究了不同厚度和不同铟含量的In_yAl_1-yAs线性渐变缓冲层对材料的表面质量、电子迁移率和二维电子气浓度的影响。结果表明,在300 K（77 K）时,电子迁移率和电子浓度分别为8 570 cm²/（Vs）^-1（23 200 cm²/（Vs）-1）3.255E12 cm^-2（2.732E12 cm^-2）。当In_yAl_1-yAs线性渐变缓冲层厚度为50 nm时,材料的表面形貌得到了很好的改善,均方根粗糙度（RMS）为0.154 nm。本研究可以为HEMT器件性能的提高提供强有力的支持。     

Enhanced performance of C60 organic field effect transistors using a tris(8-hydroxyquinoline) aluminum buffer layer

We have investigated the properties of C60-based organic field effect transistors（OFETs） with a tris（8- hydroxyquinoline） aluminum（Alq3） buffer layer inserted between the source/drain electrodes and the active material. The electrical characteristics of OFETs are improved with the insertion of Alq3 film.The peak field effect mobility is increased to 1.28×10^-2 cm²/（V·s） and the threshold voltage is decreased to 10 V when the thickness of the Alq3 is 10 nm.The reason for the improved performance of the devices is probably due to the prevention of metal atoms diffusing into the C60 active layer and the reduction of the channel resistance in Alq3 films.     

Performance improvement mechanisms of pentacene-based organic thin-film transistors using TPD buffer layer

To improve the performances of pentacene-based organic thin-film transistors (OTFTs), a TPD buffer layer was inserted between the Au metal electrode and the pentacene channel layer. As shown by the ultraviolet photoelectron spectroscopy measurement, the Au work function was increased from 4.61 eV for Au in direct contact with pentacene to 4.74 eV and 4.78 eV for the sample inserted with 2-nm-thick and 3-nm-thick TPD buffer layers, respectively, between the Au metal electrode and the pentacene channel layer. Moreover, the contact resistance was reduced from 1 MΩ to 0.1 MΩ by inserting a 2-nm-thick TPD buffer layer. Compared with the transconductance of 2.67 × 10^?7 S, the field-effect mobility of 0.46 cm²/V s, and the substhreshold swing of 1.78 V/decade for the conventional pentacene-based OTFTs without TPD buffer layer, the transconductance, the field-effect mobility, and the subthreshold swing were improved to 9.77 × 10^?7 S, 1.68 cm²/V s, and 1.46 V/decade, respectively, for the pentacene-based OTFTs inserted with a 2-nm-thick TPD buffer layer. By considering the trade-off between the increase of Au work function and the tunneling effect, the optimal thickness of the TPD buffer layer in the pentacene-based OTFTs was 2 nm.     

Color switching behaviors of organic bistable light-emitting devices fabricated utilizing an aluminum-nanoparticle-embedded tris(8-hydroxyquinoline)aluminum layer and double emitting layers

Organic bistable light-emitting devices (OBLEDs) with an aluminum (Al)-nanoparticle-embedded tris(8-hydroxyquinoline)aluminum (Alq₃) layer and double emitting layers (EMLs) were fabricated to investigate their color switching behaviors. Scanning electron microscopy images showed that Al nanoparticles were formed on the Alq₃ layer. The Al nanoparticles in the Alq₃ layer improved the storage margin of the organic bistable devices (OBDs), and the double EMLs changed the emission color of the organic light-emitting devices (OLEDs) according to the variations of the ON and the OFF states of the OBDs. The variations of the ON and the OFF states of the OBDs could be clearly distinguished by the color switching of the OLED. The luminances of the OBLEDs with double EMLs in the ON and the OFF states were 641.80 and 22.25 cd/m², respectively, and their CIE coordinates at 20 V were (0.42, 0.46) and (0.51, 0.47), respectively, which corresponded to the ON and the OFF states of the OBLEDs.     

Enhanced performance of inverted perovskite solar cells using solution-processed carboxylic potassium salt as cathode buffer layer

Using a novel solution-processed carboxylic potassium salt (F-R-COOK) as cathode buffer layer (CBL), a power conversion efficiency (PCE) of 14.37% is obtained, which is more than 51% increase compared with that of the Ag-only device under similar fabrication conditions. The test result of single electron devices and Electrochemical impedance spectroscopy (EIS) measurements demonstrate that the interlayer decreases charge transport resistance. Ultraviolet photoelectron spectroscopy (UPS) measurements are used to study the interfacial effects induced by the new CBL. It is found that F-R-COOK can reduce the work function of the Ag electrode by forming desired interfacial dipoles. Our work indicates the promising applications of F-R-COOK based CBL in perovskite solar cells and may provide some insights into the design and synthesis of new interfacial materials to further improve the device performance.     

Green- and blue-emitting tris(8-hydroxyquinoline) aluminum(III) (Alq3) crystalline polymorphs: Preparation and application to organic light-emitting diodes

Tris(8-hydroxyquinoline) aluminum(III) (Alq₃) is known to have two isomeric states, namely meridional and facial isomers. Typical Alq₃ crystals composed of meridional and facial isomers are α- and δ-form crystals, respectively. First, we investigate the temperature change in the crystalline forms of α-Alq₃ and δ-Alq₃ in X-ray diffraction experiments in a vacuum. α-Alq₃ remains in α-form up to 300 °C, immediately before sublimation. In contrast, δ-Alq₃ is found to transform into γ-form at ∼180 °C, and remain in γ-form immediately before sublimation. Both γ-Alq₃ and δ-Alq₃ are composed of facial isomers and emit blue luminescence, which is different from the typical green emissions of α-Alq₃. Second, we fabricate organic light-emitting diodes (OLEDs) from different crystals as source powders; i.e., from (1) α-Alq₃, (2) δ-Alq₃, and (3) a mixture of α-, γ-, and δ-Alq₃. All the OLEDs exhibit green electroluminescence with almost the same maximum wavelength, suggesting that some facial isomers become meridional while Alq₃ is in the gas phase. In contrast, electroluminescence efficiency depends on the Alq₃ crystalline polymorph; the OLED fabricated from the mixture of α-, γ-, and δ-Alq₃ has up to 1.4 times the efficiency of the OLED fabricated from α-Alq₃ for the same device structure.     

Enhanced performance of PbPc photosensitive organic field effect transistors by inserting different-thickness pentacene inducing layers

Lead phthalocyanine (PbPc) based photosensitive organic field effect transistors (PhOFETs) with different-thickness pentacene inducing layers (INLs) inserted between SiO₂ and PbPc layer were fabricated and characterized. The photoelectric measurements demonstrate that the device with 2-nm-thick pentacene INL exhibits the largest photoresponsivity of 505.75 mA/W and maximum photo/dark current ratio of 405.35 in all devices. For this, we give an overall explanation that different-thickness INLs display different continuity and crystallinity and thus produce strong or weak template inducing. Especially, when the INL thickness (δ) is 2 nm a quasi-continuous and highly crystalline approximate-monolayer INL forms on SiO₂ surface, which may play a strong role of template inducing, thus causing its upper PbPc film to demonstrate the strongest triclinic (3 0 0) line and the strongest NIR absorption in series PbPc films. When δ = 1 nm, pentacene does not form a continuous film. And when δ = 5 or 10 nm, a continuous multilayer INL with a declined crystallinity due to possible lattice mismatch forms on SiO₂ surface and gives a weakened template inducing. Thereby, it can be recognized that inserting a pentacene INL can markedly enhance the performance of single layer PbPc PhOFET and the optimum INL thickness is proved ∼2 nm in present conditions.