Bipolar Materials Research Articles

Blend-Based Photovoltaic Devices

We present two approaches for the fabrication of efficient photovoltaic devices. In the first one, the active layer is a bipolar material made by doping of an inert polymer with donor and acceptor molecules. In the second approach, inorganic nanoparticles are dispersed in a conjugated polymer. Photovoltaic measurements are presented for both systems.

Centrosome structure and function is altered by chloral hydrate and diazepam during the first reproductive cell cycles in sea urchin eggs

This paper explores the mode of action of the tranquillizers chloral hydrate and diazepam during fertilization and mitosis of the first reproductive cell cycles in sea urchin eggs. Most striking effects of these drugs are the alteration of centrosomal material and the abnormal microtubule configurations during exposure and after recovery from the drugs. This finding is utilized to study the mechanisms of centrosome compaction and decompaction and the dynamic configurational changes of centrosomal material and its interactions with microtubules. When 0.1% chloral hydrate or 350-750 microM diazepam is applied at specific phases during the first cell cycle of sea urchin eggs, expanded centrosomal material compacts at distinct regions and super-compacts into dense spheres while microtubules disassemble. When eggs are treated before pronuclear fusion, centrosomal material aggregates around each of the two pronuclei while microtubules disappear. Upon recovery, atypical asters oftentimes with multiple foci are formed from centrosomal material surrounding the pronuclei which indicates that the drugs have affected centrosomal material and prevent it from functioning normally. Electron microscopy and immunofluorescence studies with antibodies that routinely stain centrosomes in sea urchin eggs (4D2; and Ah-6) depict centrosomal material that is altered when compared to control cells. This centrosomal material is not able to reform normal microtubule patterns upon recovery but will form multiple asters around the two pronuclei. When cells are treated with 0.1% chloral hydrate or 350-750 microM diazepam during mitosis, the bipolar centrosomal material becomes compacted and aggregates into multiple dense spheres while spindle and polar microtubules disassemble. With increased incubation time, the smaller dense centrosome particles aggregate into bigger and fewer spheres. Upon recovery, unusual irregular microtubule configurations are formed from centrosomes that have lost their ability to reform normal mitotic figures. These results indicate that chloral hydrate and diazepam affect centrosome structure which results in the inability to reform normal microtubule formations and causes abnormal fertilization and mitosis.

Tem Studies of Polysilicon Emitter Bipolar Materials & Devices: Increased Interfacial Oxide Break-Up and Polysilicon Regrowth and Decreased Emitter Resistance by Fluorine Implantation

AbstractThe role of fluorine (F) in the break-up of the native oxide and the regrowth of As doped poly-Si layers on unpatterned Si wafers and on patterned regions of Si device wafers at temperatures of 900°C to 1000°C are investigated by TEM and by the fabrication of npn poly-Si emitter bipolar devices. Results for unpatterned wafers with F show i) a 950°C dopant drive-in anneal causes oxide break-up and regrowth after a time suitable for the fabrication of devices, ii) a pre-anneal, before the As implant, further enhances the break-up and regrowth and iii) there is an optimum F dose of 5×1015/cm2. Based on these results poly-Si emitter bipolar devices were fabricated using F=5×1015/cm2, a pre-anneal and a 900°C As drive-in anneal. The results establish quantitatively the relationship between the interface structures and the specific emitter resistance, i.e. with no F there is no break-up or regrowth and the emitter resistance is high (114Ωμm2) while with F there is break-up and regrowth and the emitter resistance is low (17Ωμm2).

Production of ethene oxide in a sieve plate electrochemical reactor Part I: Influence of sieve plate design, electrode material and pH

The performance of a sieve plate electrochemical reactor for the production of ethene oxide by the indirect electrochemical oxidation of ethene is reported. The oxidant is anodically generated bromine solution. The sieve plate reactor consists of a stack of bipolar electrodes situated above a sieve plate gas distributor. Two bipolar electrode materials are used graphite and IrO2 coated Ebonex®. The influence of different sieve plate designs on performance is described. Control of electrolyte pH is shown to be an important requirement for efficient reactor operation.