Harnessing the sun's infrared spectrum in large-area photovoltaic devices

太阳光带到地球表面的能量比我们每天通过所有生产来源消耗的能量多一万倍-核能，化石能源，水力发电。整个北美的能源需求可以通过覆盖200 x200公里的区域，使用20%的功率效率的太阳能电池来满足。虽然这只是北美大陆的一小部分，但对于电子设备来说，这是一个巨大的区域。今天，这些往往是由晶体半导体，如硅，砷化镓，或磷化铟。构建器件需要洁净室条件和采用诸如光刻、干法蚀刻和蒸发金属化等方法的顺序工艺流程。在这样的范例内建造平方公里的光电设备是不可想象的。柔性光电子技术将大面积器件带入了想象的领域。基于溶液加工和相关涂层技术制造的塑料光电器件可以使用类似于报纸印刷的卷对卷工艺制造。初创公司已经开始将制造大面积可印刷太阳能电池的技术商业化。涂层设备供应商正在将其现有的专业知识应用于大面积可印刷光电子产品。整个领域都在等待更高效的太阳能电池。今天的塑料太阳能电池只捕捉可见光波长范围内的太阳光线。事实上，到达地球的太阳能量有一半是在红外波长范围内。2005年初，我们在《自然材料》杂志上报道了第一个塑料太阳能电池，它可以捕捉太阳的红外线。这个第一个设备效率不高。在本项目中，我们建议追求红外敏感塑料光致发光器件的功率转换效率的最大化。我们的目标是红外线功率转换效率达到1%，这将使我们的技术进入商业相关领域。

The sun's rays carry to the earth's surface ten thousand times more energy than we consume each day via all sources of production - nuclear, fossil, hydroelectric power combined. The entirety of North America's energy needs could be met by covering an area 200x200 kilometers with 20%-power-efficient solar cells. While this is a small fraction of the North American continent, it is a huge area for an electronic device. Today, these tend to be made from crystalline semiconductors such as silicon, gallium arsenide, or indium phosphide. Building devices requires cleanroom conditions and a sequential process flow employing methods such as optical lithography, dry etching, and evaporative metallization. To build square kilometers of optoelectronic device within such a paradigm is unimaginable. Flexible optoelectronics brings large device areas into the realm of the imaginable. Plastic optoelectronic devices, made based on solution-processing and related coating technologies, can be made using a roll-to-roll process akin to the printing of newspapers. Start-up companies have already begun commercialization of the technologies to make large-area printable solar cells. Suppliers of coating equipment such are adapting their established expertise in the direction of large-area printable optoelectronics. The entire field is waiting for a more efficient solar cell. Today's plastic solar cells capture only the sun's rays which lie in the visible wavelength range. In fact, half of the sun's power reaching the earth lies in the infrared wavelength range. We reported in early 2005 in the journal Nature Materials the first-ever plastic solar cell which captures the sun's infrared rays. This first-ever device was not efficient. In the present project, we propose to pursue the maximization of the power-conversion efficiency of infrared-sensitive plastic photovoltaics. We target 1% power conversion efficiency in the infrared as proof-of-principle goal which will enter our technology into the realm of commercial relevance.