Enhanced photosensitivity of InGaZnO-TFT with a CuPc light absorption layer

A copper phthalocyanine (CuPc) organic semiconductor is capped onto an amorphous indium–gallium–zinc-oxide (InGaZnO) thin film transistor (TFT) to enhance the photosensitivity of InGaZnO-TFT. The CuPc organic semiconductor is served as a light absorption layer and forms a p–n junction with the InGaZnO film. After 60 s white light illumination, light responsivity (R) of InGaZnO-TFT with a CuPc light absorption layer reaches a value of 148.5 A/W at a gate-source voltage (V_GS) of 20 V, which is much larger than that (31.2 A/W) of the conventional InGaZnO-TFT. The results are attributed to the following mechanism. First, a CuPc layer is employed as the light absorption layer. Second, CuPc/InGaZnO p–n junction enables the injection of electron into InGaZnO film. Our results indicate that using CuPc as light absorption layer is an effective approach to improve the photosensitivity of InGaZnO-TFT.     

High-performance n-channel organic thin-film transistors based on the dual effects of heterojunction and surface modification

This paper presents two n-channel organic heterojunction transistors with modified insulator by using hexadecafluorophthalocyaninatocopper (F₁₆CuPc)/copper phthalocyanine (CuPc) and F₁₆CuPc/pentacene as the active layers. Compared with a single-layer device, it reports that an improved field-effect mobility and a 6-fold higher drain current are observed. The highest mobility of 0.081~cm²/(V.s) was obtained from F₁₆CuPc/CuPc heterojunction devices. This result is attributed to the dual effects of the organic heterojunction and interface modification. Furthermore, for two heterojunction devices, the performance of the F₁₆CuPc/CuPc-based transistor is better than that of F₁₆CuPc/pentacene. This is attributed to the morphologic match of two organic components.     

A hybrid photodiode with planar heterojunction structure consisting of ZnO nanoparticles and CuPc thin film

A photodiode with planar heterojunction was fabricated using copper (II) phthalocyanine (CuPc) organic semiconductor and zinc oxide (ZnO) inorganic nanoparticles (NPs, ～5 nm). The current–voltage (I–V) characteristics of ITO/ZnO NPs/CuPc/Ag device in dark and under illumination with a solar simulator were investigated in detail. The measurement results showed that the device exhibited good rectifying behavior in dark and under illumination. A rectification ratio (RR) of 15.44 at 1.95 V was achieved for the device under 100 mW/cm² illumination power. Also, the RR of the device as a function of light intensity was observed. The photoresponsive mechanism of the photodiode was illuminated in term of its energy band diagram.     

Effect of net carriers at the interconnection layer in tandem organic solar cells

Tandem cell with structure of indium tin oxide (ITO)/molybdenum oxide (MoO₃)/fullerene (C60)/copper phthalocyanine (CuPc)/C60/tris-8-hydroxy-quinolinato aluminum (Alq₃)/Al was fabricated to study the effect of net carriers at the interconnection layer. The open circuit voltage and short circuit current were found to be 1.15 V and 0.56 mA/cm², respectively. Almost the same performance (1.05 V, 0.58 mA/cm²     

新型苯乙烯衍生物掺杂的蓝色及白色有机电致发光器件

研究了新型高效蓝色掺杂剂EBDP的电致发光性能. 分别以EBDP为掺杂剂制备了结构为氧化铟 锡(ITO)/酞菁铜(CuPc)/N,N′-二(1-萘基)-N,N′-二苯基-1,1′-联苯-4-4′-二胺(NPB)/2- 叔丁基-9,10-二-(2-萘基)蒽(TBADN):EBDP/8-羟基喹啉铝(Alq₃)/LiF/Al 与ITO /CuPc/NPB/TBADN:EBDP: 4-二氰亚甲基-2-叔丁基-6-(1,1,7,7-四甲基久咯呢定基-9-烯基)- 4H-吡喃/Alq_{3 关键词： 有机电致发光 蓝色掺杂剂 蓝色电致发光器件 白色电致发光器件}     

Electronic properties of the organic semiconductor hetero-interface CuPc/C60

We present a study of the electronic properties of the interface between the well-established molecular organic semiconductor copper phthalocyanine (CuPc) and the fullerite C₆₀ using photoelectron spectroscopy and the Kelvin-probe (KP) method. Upon deposition of CuPc on C₆₀, we found interfacial shifts of the vacuum level indicating the formation of a dipole layer, while band bending is found to be negligible. The interface dipole of 0.5 eV measured with KP is close to the difference between the work functions of bulk CuPc and C₆₀. No evidence for a chemical interaction at the interface is concluded from the absence of additional features in the core-level spectra at the earliest stages of deposition. The energy-level alignment diagram at the CuPc/C₆₀ interface is derived.     

Influence of self-assembly monolayers on the characteristics of copper phthalacyanine thin film transistor

Self-assembly monolayers (SAMs) of octadecyltrichlorosilane (OTS) on a silicon dioxide substrate were formed in solution, or by vacuum vapor methods, and characterized by Fourier transform infrared (FTIR) spectroscopy. We found that the OTS SAMs on SiO₂ substrates greatly affect the order and connectivity of evaporated copper phthalocyanine (CuPc) thin films, as confirmed by an atomic force microscopy (AFM) and X-ray diffraction analysis. The performance of the organic CuPc thin film transistor comprising OTS SAMs interposed between a gate dielectric and an organic semiconductor layer could be effectively enhanced as a result of improvements in the quality both of the organic/dielectric interface and the evaporated CuPc thin films. The deposition of an OTS SAM leads to a mobility of 1.48×10^-3 cm²/Vs, 1–2 orders higher than that of bare silicon dioxide. PACS 73.61.Ph; 85.30.Tv; 78.66.Tr     

Formation of sharp metal-organic semiconductor interfaces: Ag and Sn on CuPc

A detailed investigation of the chemistry and electronic structure during the formation of the interfaces between thin films of the archetypal organic molecular semiconductor copper phthalocyanine (CuPc) and Ag or Sn deposited on it was performed using photoemission and near-edge X-ray absorption spectroscopies with synchrotron light. Our study demonstrates the formation of sharp, abrupt interfaces, a behavior which is of particular importance for applications in organic devices. Moreover, for Ag on CuPc we demonstrate that this interface is free from any reaction, whereas there is slight interface reaction for Sn/CuPc.     

Electro-optical characterization and analysis of CuPc-based solar cells with high photovoltage

Organic solar cells using the CuPc and PTCBI semiconductor layers were studied. A high open circuit voltage of 1.15 V was obtained in a device with ITO/PEDOT:PSS/CuPc (15 nm)/PTCBI (7 nm)/Al structure. Results were interpreted in terms of a modified CuPc-Al Schottky diode for the thin PTCBI case and a CuPc-PTCBI heterojunction for the thick PTCBI case. Also, the formation of a thin aluminum oxide layer under the aluminum electrode was postulated. This layer has a beneficial aspect wherein shunting losses are reduced and a high photovoltage is enabled. However, it adds greatly to the series resistance to a point where the short circuit current density is reduced. CuPc Schottky diodes with an ITO/PEDOT:PSS/CuPc/Al structure yielded a high V _oc of 900 mV for a CuPc layer of thickness 140 nm. The V _oc increased with increase in CuPc layer thickness.     

Detailed analysis of ultrathin fluorescent red dye interlayer for organic photovoltaic cells

The influence of an ultrathin 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) fluorescent dye layer at donor/acceptor heterojunction on the performance of small-molecule organic photovoltaic (OPV) cell is studied. The structure of OPV cell is of indium-tin oxide (ITO)/copper phthalocyanine (CuPc)/DCJTB/fullerene (C₆₀)/bathophenanthroline (Bphen)/Ag. The results show that open circuit voltage (V_OC) increases to 0.57 V as the film thickness of DCJTB layer increases from 0.2 to 2.0 nm. By using an equivalent circuit model, the enhancement of V_OC is found to be attributed to the reduced reverse saturation current density (J_S) which is due to the lower highest occupied molecular orbital (HOMO) level in DCJTB than that in CuPc. Also, the short circuit current density (J_SC) is affected when the DCJTB layer becomes thicker, resulting from the high series resistance R_SA due to the low charge carrier mobility of fluorescent red dye.     

High-contrast and high-efficiency top-emitting organic light-emitting devices

The reflection properties of top-emitting organic light-emitting devices with different electrodes and organic layers were calculated. The results guided the fabrication of a high-contrast device: Au/copper phthalocyanine (CuPc: 35 nm)/N,N’-bis-(1-naphthyl)-N,N’diphenyl-1,1’ biphenyl-4,4’diamine (NPB: 15 nm)/tris(8-hydroxyquinoline) aluminum (Alq₃: 50 nm)/Sm (35 nm)/Alq₃ (65 nm). The device has a contrast ratio of 8.3:1 at a luminance of 300 cd/m² under 1000 lx ambient light, and a maximum luminance and efficiency of 5000 cd/m² and 4.14 cd/A, respectively. The high contrast is attributed to the moderate reflection of Au at 380–550 nm, low reflection of Sm in the visible range, and high absorption of CuPc at 600–700 nm. PACS 85.60.Jb; 78.20.Ci; 78.40.-q     

Structure and morphology of CuPc and F16CuPc pn heterojunction

This article reports structure and morphology of copper phthalocyanine (CuPc) and fluorinated copper phthalocyanine (F₁₆CuPc) pn heterojunction. Highly ordered CuPc and F₁₆CuPc polycrystalline thin films with the 2 0 0 plane spacing s of 1.30 and 1.56 nm, respectively, could be continuously grown via an intermediate-phase layer. Compared with CuPc, the intermediate-phase layer is much thinner when F₁₆CuPc is used as the first layer. The rougher the first layer is, the thicker the intermediate-phase layer is. Similarly, the 2 0 0 plane spacings of the intermediate-phase layer are dependent on morphology of the first layer. Furthermore, morphology of the heterostructure is mainly dominated by that of CuPc films. Due to the thicker intermediate-phase layer in the CuPc/F₁₆CuPc heterostructure, the thin film transistors (TFT) performance is obviously inferior to that of the F₁₆CuPc/CuPc device.     

Nuclear detectors based on n-silicon/copper–phthalocyanine heterojunctions

Nuclear detectors based on n-silicon/copper–phthalocyanine (CuPc) heterojunctions have been fabricated using thermally evaporated CuPc thin films. Two different materials (Au and Al) have been employed to make contact to CuPc. Current–voltage (I–V) characteristics and energy spectra obtained on exposure of the detectors to α-particles have been compared with conventional Au/n-Si surface barrier detector. The results show that the detectors with Au as well as Al contact show characteristics comparable to Au/n-Si detectors. The results have been understood in terms of the band diagram of the junctions formed.     

Influence of the substrate temperature during deposition on film characteristics of copper phthalocyanine and field-effect transistor properties

In this paper, we employ different substrate temperatures during the deposition process and observe a highly ordered structure and strong orientation of copper phthalocyanine (CuPc) molecules on Si/SiO₂ by using X-ray-diffraction and transmission electron microscopy analysis. The results show the effect of CuPc morphology at different substrate temperatures on the organic field-effect-transistor performance. When the substrate temperature for deposition of CuPc is 120 °C, a mobility of 3.75×10^-3 cm²/V s can be obtained. PACS 73.61.Ph; 85.30.Tv; 78.66.Tr     

Effect of Copper Phthalocyanin Nanostructures on the Photovoltaic Characteristics of a Polymer Solar Cell

Russian Physics Journal - The results of studying the influence of copper phthalocyanine (CuPc) nanostructures on the generation and transfer of charge carriers in the semiconductor polymer...     

Enhancement of photocatalytic degradation of polyethylene plastic with CuPc modified TiO2 photocatalyst under solar light irradiation

Solid-phase photocatalytic degradation of polyethylene (PE) plastic, one of the most common commercial plastic, over copper phthalocyanine (CuPc) modified TiO₂ (TiO₂/CuPc) photocatalyst was investigated in the ambient air under solar light irradiation. Higher PE weight loss rate, greater texture change; more amount of generated CO₂, which is the main product of the photocatalytic degradation of the composite PEC plastic can be achieved in the system of PE-(TiO₂/CuPc) in comparison with PE-TiO₂ system. The CuPc promoted charge separation of TiO₂ and enhanced the photocatalytic degradation of PE based on the analysis of surface photovoltage spectroscopy (SPS). During the photodegradation of PE plastic, the reactive oxygen species generated on TiO₂ or TiO₂/CuPc particle surfaces play important roles. The present study demonstrates that the combination of polymer plastic with TiO₂/CuPc composite photocatalyst in the form of thin film is a practical and useful way to photodegrade plastic contaminants under solar light irradiation.     

Impedance spectroscopy studies on CuPc/n-Si hybrid solar cell

Impedance spectroscopy of copper phthalocyanine (CuPc)/n-Si hybrid solar cell was studied. The dielectric relaxation mechanism of the solar cell was analyzed by Cole–Cole plots, indicating the presence of a single relaxation mechanism. The equivalent circuit model consisting of a parallel resistor and capacitor in series with a resistor was found to give a well fit to the experimental data. The conduction mechanism was suggested to be a space-charge limited current with exponential trap distribution. Beside, the dielectric relaxation time of the device was decreased with increasing applied bias voltages.     

酞菁铜与MoS_2(0001)范德瓦耳斯异质结研究

利用光电子能谱、原子力显微镜以及低能电子衍射等表面研究手段系统研究了真空沉积生长的酞菁铜薄膜与衬底MoS2(0001)之间的范德瓦耳斯异质结界面电子结构和几何结构.角分辨光电子能谱清楚地再现了MoS2(0001)衬底在Γ点附近的能带结构.低能电子衍射结果表明,CuPc薄膜在MoS2(0001)表面沿着衬底表面[11ˉ20],[1ˉ210]和[ˉ2110]三个晶向有序生长,反映了衬底对CuPc的影响.原子力显微镜结果表明,CuPc在MoS2衬底上遵循层状-岛状生长模式:在低生长厚度下(单层薄膜厚度约为0.3 nm),CuPc分子平面平行于MoS2表面上形成均匀连续的薄膜;在较高的沉积厚度下,CuPc沿衬底晶向形成棒状晶粒,表现出明显的各向异性.光电子能谱显示界面偶极层为0.07 eV,而且能谱在膜厚1.2 nm饱和,揭示了酞菁铜与MoS2(0001)范德瓦耳斯异质结的能级结构.     

Orientation-dependent ionization potential of CuPc and energy level alignment at C60/CuPc interface

The electronic structure evolution of interfaces of fullerene (C₆₀) with copper phthalocyanine (CuPc) on highly oriented pyrolytic graphite (HOPG) and on native silicon oxide has been investigated with ultraviolet photoemission spectroscopy and inverse photoemission spectroscopy. The LUMO edge of C₆₀ was found to be pinned at the interface with CuPc on SiO₂. A substantial difference in the electron affinity of CuPc on the two substrates was observed as the orientation of CuPc is lying flat on HOPG and standing up on SiO₂. The ionization potential and electron affinity of C₆₀ were not affected by the orientation of CuPc due to the spherical symmetry of C₆₀ molecules. We observed band bending in C₆₀ on the standing-up orientation of CuPc molecules, while the energy levels of C₆₀ on the flat-lying orientation of CuPc molecules were observed to be flat. The observation points to a dependence of photoexcited charge transfer on the relative molecular orientation at the interface.     

Reduction of driving voltage in organic light-emitting diodes with molybdenum trioxide in CuPc/NPB interface

A novel structure of organic light-emitting diode was fabricated by inserting a molybdenum trioxide (MoO₃) layer into the interface of hole injection layer copper phthalocyanine (CuPc) and hole transport layer N,N′-diphenyl-N,N′-bis(1-napthyl-phenyl)-1,1′-biphenyl-4,4′-diamine (NPB). It has the configuration of ITO/CuPc(10 nm)/MoO₃(3 nm)/NPB(30 nm)/ tris-(8-hydroxyquinoline) aluminum (Alq₃)(60 nm)/LiF(0.5 nm)/Al. The current density-voltage-luminance (J-V-L) performances show that this structure is beneficial to the reduction of driving voltage and the enhancement of luminance. The highest luminance increased by more than 40% compared to the device without hole injection layer. And the driving voltage was decreased obviously. The improvement is ascribed to the step barrier theory, which comes from the tunnel theory. The power efficiency was also enhanced with this novel device structure. Finally, “hole-only” devices were fabricated to verify the enhancement of hole injection and transport properties of this structure.