Publications by authors named "Steven Tierney"

Unlabelled: The impact of side-chain variations on the photothermal stability of solar cells containing poly(benzodithiophene-diketopyrrolopyrrole) polymers are investigated in the absence of oxygen. Four different side-chains of benzodithiophene (BDT) are synthesized and copolymerized with diketopyrrolopyrrole (DPP) by Stille polymerization. The photothermal stability is measured as active layer blends with phenyl-C61-butyric acid methyl ester (PCBM) in encapsulated inverted photovoltaic cell architecture with zinc oxide and

Pedot: PSS as transport layers (ITO/ZnO/active layer/

Pedot: PSS/Ag).

View Article and Find Full Text PDF

We report hole mobilities obtained computationally based on both single crystal geometries and those obtained from crystal fragments optimised on a model surface. Such computational estimates can differ considerably from experimentally measured thin film mobilities. One source of this discrepancy is due to a difference in the morphology of the thin film compared with that of the crystal.

View Article and Find Full Text PDF

Herein, we analyze charge carrier mobility and morphology of the active blend layer in thin film organic solar cells and correlate them with device parameters. A low band gap donor-acceptor copolymer in combination with phenyl-C61-butyric acid methyl ester (PCBM) or two bis-adduct fullerenes, bis-PCBM and bis-o-quino-dimethane C60 (bis-oQDMC), is investigated. We study the charge transport of polymer:fullerene blends in hole- and electron-only devices using the space-charge limited current method.

View Article and Find Full Text PDF

Depositing a fused-ring thieno-thiophene polymer on different self-assembled monolayers indicates that varying the SAM surface energy changes the FET mobility and turn-on voltage by varying polymer crystallinity at the buried interface.

View Article and Find Full Text PDF

The Positive Reinforcement Opportunity Project (PROP) was a pilot program developed to build on the efficacy of contingency management (CM) using positive reinforcement to address the treatment needs of gay and bisexual men currently using crystal methamphetamines (meth). It was hypothesized that a version of CM could be implemented in San Francisco that was less costly than traditional treatment methods and reached gay and other MSM using meth who also engaged in high-risk sexual activity. Of the 178 men who participated in PROPfrom December 2003 to December 2005, many self-reported behaviors for acquiring and spreading sexually transmitted diseases including HIV infection.

View Article and Find Full Text PDF

Organic electronics technology, in which at least the semiconducting component of the integrated circuit is an organic material, offers the potential for fabrication of electronic products by low-cost printing technologies, such as ink jet, gravure offset lithography and flexography. The products will typically be of lower performance than those using the present state of the art single crystal or polysilicon transistors, but comparable to amorphous silicon. A range of prototypes are under development, including rollable electrophoretic displays, active matrix liquid crystal (LC) displays, flexible organic light emitting diode displays, low frequency radio frequency identification tag and other low performance electronics.

View Article and Find Full Text PDF