Sep 8 2006
Imagine T-shirts that light up, or a beach umbrella that collects solar energy to run a portable TV. How about really cheap solar collectors for the roof?
所有这些以及更多的可能来自于康奈尔这展示了一种新型的有机半导体装置，该设备显示了电致发光并充当光伏电池。该设备是第一个使用“离子结”的设备，研究人员说，这可能会改善性能。由于有机半导体可以用薄而灵活的床单制成，因此可以在布或纸上创建显示器。
"Flexible means low-cost fabrication," said George Malliaras, Cornell associate professor of materials science and engineering, in whose laboratory the research was done. And that means another result of the research could be mass-produced, inexpensive solar cells.
The work is described in the Sept. 7 issue of the journal欧洲杯线上买球在康奈尔大学研究生研究人员丹尼尔·伯纳德（Daniel Bernards）和塞缪尔·弗洛雷斯（Samuel Flores-Torres）的一篇论文中，康奈尔（Cornell）的E. M. Chamot化学与化学生物学教授和Malliaras的论文。
Semiconductors -- organic or otherwise -- are materials that contain either an excess of free electrons (N-type) or "holes" (P-type). Holes are spaces where an atom ought to have an electron but doesn't, representing a positive charge. N- and P-type materials can be joined to form diodes and transistors. The Cornell researchers went a step further by making a diode out of organic semiconductors that also contain free ions (molecules with an electrical charge). They laminated together two organic layers, one that contained free positive ions and the other negative ions. They then added thin conducting films on the top and bottom; the top conductor is transparent to allow light in and out.
在两部胶片相遇的地方，负离子在整个连接处迁移到正面，反之亦然，直到达到平衡为止。研究人员说，这与硅二极管中发生的事情相似，电子和孔在该交界处迁移。
When a voltage is applied across the top and bottom electrodes, a current flows through the junction in the form of electrons moving one way while holes move the other way. The migration of ionic charge across the junction causes a higher potential (voltage difference) than normal, which affects the way electrons combine with holes. This raises the energy of the molecules, which quickly release the energy as photons of light. The junction shows "intense light emission," the researchers said in their paper.
On the other hand, when a bright light is applied, photons are absorbed by the molecules, causing them to kick out electrons. The ionic charges create a "preferential direction" for the electrons to move, and a current flows.
The collection of charges also allows electrons and holes to move across the junction easily in one direction but only weakly in the other, making the device a rectifier. It may be possible, Malliaras said, to change the configuration of the ionic charge by applying a voltage to the device, telling it whether to conduct or not, so organic diodes might be used as components for computer memory.
Since the device was created by laminating together materials that are flexible, large quantities could be manufactured very cheaply by feeding two films together from rolls, Malliaras said. The next step, he added, is to try modifying the metal content of the semiconductors to make more efficient materials.
他说：“我们可以使用大量材料。”欧洲杯足球竞彩
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