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

太阳光携带到地球表面的能量是我们每天通过所有生产来源——核能、化石燃料、水力发电——消耗的能量的总和的一万倍。用20%节能的太阳能电池覆盖200x200公里的面积，就能满足整个北美的能源需求。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。建筑设备需要洁净室条件和采用光学光刻、干蚀刻和蒸发金属化等方法的连续工艺流程。在这样的模式下建造平方公里的光电器件是不可想象的。柔性光电子技术将大型器件区域带入可想象的领域。基于溶液处理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打印太阳能电池的技术商业化。诸如此类的镀膜设备供应商正在调整其在大面积可印刷光电子方向的既定专业知识。整个领域都在等待一种更高效的太阳能电池。今天的塑料太阳能电池只能捕捉可见光范围内的太阳光。事实上，到达地球的太阳能量的一半位于红外波长范围内。2005年初，我们在《自然材料》杂志上报道了第一个可以捕捉太阳红外线的塑料太阳能电池。这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伏的功率转换效率最大化。我们的目标是1%的红外功率转换效率作为原理验证的目标，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.