Simultaneous optimization of charge-carrier mobility and optical gain in semiconducting polymer films
Efficient light emission combined with high charge-carrier mobility has proven elusive for polymer semiconductors, because high mobility is typically achieved using approaches that quench luminescence. A new strategy, introducing a limited number of more-effective hopping sites between otherwise relatively isolated polymer chains, achieves this aim.
Democrat Barack Obama's appeal to  centrist voters has further opened the door to Republican claims his message of change only applies to the positions he has taken in the past.
AP - Iran indicated Saturday that it has no plans to meet a key Western demand that it stop enriching uranium, a day after Tehran sent the European Union a response to an international offer of incentives for halting enrichment.
AP - The call girl involved in a scandal that brought down New York's former governor has dropped a lawsuit claiming "Girls Gone Wild" founder Joe Francis exploited her image and name on the Internet.
