New Efficient Organic Compounds In Dye-Sensitized Solar Cells

We demonstrate the use of three new organic photosensitizer compounds in dye sensitized solar cells (DSSCs). One of these compounds is a diazapentadiene derivative [1], while the other two compounds are triazole derivatives [1]. The construction of the cell involved use of a commercially available indium tin oxide (ITO) conductive electrode on which a thin layer of TiO2 was deposited by chemical vapor deposition (CVD). The other electrode was composed of a thin graphitic layer on ITO. A gelled iodine/iodide combination was used as the redox system. We have studied the current versus voltage (IV) characteristics and the power versus voltage of these DSSCs at a relatively low light intensity. The efficiency and the fill factor for each cell were consequently calculated

ELECTROLUMINESCENCE FROM A SINGLE LAYER OF POLY(N-VINYLCARBAZOLE) DOPED WITH A NEW 1,2,4-TRIAZOLE DERIVATIVE

We report light emission from a single layer thin film device. This device is comprised of a hole transporting polymer, poly(N-vinylcarbazole) (PVK) doped with a new luminescent 1,2,4-triazole derivative sandwiched between an indium tin oxide electrode (ITO) and an aluminum electrode. We have studied the current versus voltage (I-V) characteristics, the electroluminescence versus voltage (EL-V) characteristics, and the lifetime of the device. Thinner samples revealed a lower EL threshold voltage VT compared with the conventional organic light emitting diodes (OLEDs) reported in the literature. This VT increased with increasing the sample thickness

Electroluminescence from Single Layer Poly (N-vinylcarbazole) Films Doped with New Emitter Molecules

Organic compounds have been used for a long time as insulators in electronic devices. However the discovery of conductive polymers, the development of photoconducting organic materials, and the vast amount of research effort on conjugated semiconductors have demonstrated that some organic materials can be the basis for a wide range of electronic and opto-electronic devices [1–7]. Organic light-emitting diodes (OLEDs) have attracted a great deal of interest as display systems since their discovery by Tang [1]. Much progress has been achieved and the device performance has improved dramatically since then [2, 8–10]. One of the advantages of an OLED display over the traditional liquid crystal LCD display is that OLEDs do not require a backlight to function. This means that OLEDs draw far less power. Also, OLED displays have a wide viewing angle

A polynomial approach for reflection, transmission, and ellipsometric parameters by isotropic stratified media

A polynomial approach for the calculation of the reflectance, the transmittance, and the ellipsometric parameters of a stratified isotropic planar structure is presented. We show that these parameters can be written in a very simple and compact form using the so-called elementary symmetric functions that are extensively used in the mathematical theory of polynomials. This approach is applied to quarter-wave Bragg reflectors. The numerical results reveal an exact match with the well known matrix formalism

Rotating polarizer-analyzer scanning ellipsometer

A spectroscopic ellipsometer in which the polarizer and the analyzer are rotating synchronously in opposite directions at the same speed is proposed. The light intensity involves four components, one dc and three cosine terms, with frequencies of ω, 2ω, and 3ω. The main advantage of the proposed ellipsometer is that: it is feasible to extract the ellipsometric parameters ψ and Δ from the even Fourier coefficients without relying on the dc component which is considered to be a serious problem in rotating-analyzer or -polarizer ellipsometer. This allows measurements in semi-dark room without worrying about stray light problems, dark currents in detectors, and long term fluctuations in light sources. The calculations of the optical parameters of c-Si, Au, and GaAs are in excellent agreement with the published data

Characterization of Poly (9-vinylcarbazole) and 8-Hydroxyquinoline Aluminum Using a Homemade Rotating Analyzer Ellipsometer

In this work we use a homemade spectroscopic ellipsometer to study two commonly used organic materials; namely poly (9-vinylcarbazole)(PVK) and 8-hydroxyquinoline aluminum (Alq3). The ellipsometric parameters ψ and Δ are measured as a function of the wavelength. Fresnel's equations are then inverted to obtain the optical parameters and the thickness of these samples. The dispersion of the refractive index of Alq3 and PVK thin films is found to obey Cauchy’s equation

دراسة الخصائص الضوئية لـ poly(9-vinylcarbazole) and 8-hydroxyquinoline aluminum باستخدام مقياس الاستقطاب الطيفي المصنع محلياً

In this work we use a homemade spectroscopic ellipsometer to study two commonly used organic materials; namely poly(9-vinylcarbazole) (PVK) and 8-hydroxyquinoline aluminum (Alq 3). The ellipsometric parameters and are measured as a function of the wavelength. Fresnel's equations are then inverted to obtain the optical parameters and the thickness of these samples. The dispersion of the refractive index of Alq 3 and PVK thin films is found to obey Cauchy's equation. poly(9-vinylcarbazole) and 8-hydroxyquinoline aluminum : poly(9-vinylcarbazole) (PVK) and 8-hydroxyquinoline aluminum (Alq 3) .نستخدم مقياس الاستقطاب الطيفي المصنع محلياً لدراسة الأفلام الرقيقة لمادتين عضويتين شائعتي الاستخدام وهما poly(9-vinylcarbazole) (PVK) and 8-hydroxyquinoline aluminum (Alq3)، نقوم بقياس معاملات مقياس الاستقطاب الطيفي كدوال في الطول الموجي للضوء الساقط على العينة، ثم نستخدم معادلات فرينل لحساب المعاملات الضوئية وسمك هذه الأفلام، وكذلك وجد أن انتشار معامل الإنكسار يتبع معادلة كوشي لكل عينة

Abdel-Latif, “Dye-sensitized solar cells based on ZnO films and natural dyes

Abstract This work emp loys extracts fro m Walnuts, Rhubarb, and Po megranate as natural dyes for fabricat ion of dye-sensitized solar cells (DSSCs). ZnO nanoparticles with crystallite mean value 12 n m as confirmed fro m XRD data have been synthesized at pH 12. SEM p icture of the ZnO powder reveals ho mogeneous and well defined nanoparticles with size of about 15 n m. TEM micrograph shows that the powder has a porous agglomerate structure consisting main ly of spherical crystalline particles with about 15-20 n m diameter. ZnO films were deposited on Fluorinated Tin Oxide (FTO) coated glass sheets followed by sintering at 450℃. The samples were sensitized by soaking in the dye solution. A Graphite slab was used as a back electrode, and redo x was employed as an electrolyte. Each cell was illu minated with light intensities in the range 40,000-100,000 Lux to measure the photovoltaic parameters. The experimental results shows that the highest I sc value is obtained fro m the DSSC sensitized with Rhubarb extract while the highest V oc value is obtained from the DSSC sensitized with the Walnuts extract. The P max of the DSSC sensitized by the Walnuts extract is greater than those sensitized by Rhubarb and Po megranate ext racts. Moreover, the open circuit voltage V oc decay was found to closely fo llo w a pseudo single exponential form