The answer to the question posed above isn't clear. I went to a session about plastic devices that could be used as solar cells instead of expensive silicon, hoping to hear a breathrough was nigh. Sadly i was wrong. Advances in plastics that can capture light over a useful wavelength, that can separate the charge into electrons and holes, that can carry that charge and finally, do something useful with it are being made. But slowly.
Talking in the session was Fred Wudl, who was first to develop fullerene/polymer systems as photovoltaic cells. It seems that the system he hit upon first up has been hard to beat, at least according to Mats Andersson, from Chalmers University of Technology, Gothenburg, who was also speaking in the session.
Percentage power conversion efficiencies remain low. The very best results are around 5%, and these tend to be from a single, meticulously prepared sample - a long way from a manfacturable, large scale printing porcess that is hoped for. To be really viable, a system that is 10% efficient is needed, or a slightly less efficient, but very cheap plastic material that can be made to cover a large area. But still, despite lots of tinkering with the polymers in the systems, the best that Andersson presented was 2.8% efficiency. Manpreet Kaur, from Virginia polytechnic presented a system with an efficiency of 1%.
The systems rely on the electron-transporting porperties of a polymer, and the hole (absence of electron) transporting properties of the fullerene groups. The main way to change these systems is altering the polymer groups.
The field is gaining strength, however. One company, Konarka, is claiming that it will have a flexible, efficient, solar cell plastic available by the end of the year. We shall have to wait and see.
The session certainly generated interest, but i can't help think that the efficiencies are going to remain low for a while yet. Perhaps next year, if Konarka has delivered, academics will have joined them in finding a more efficient system.
译文:
美国化学学会费城2008年会议:廉价的太阳能何时实现？
关于本文题目提出的问题，其答案还不明确。我参加了一个会议，主要讨论用塑料作太阳能电池，以替代昂贵的硅太阳能电池。在会上，我本来希望听到在这方面有所突破。但遗憾的是，我的期望落空了。的确，在以下方面已有所进展：即——可利用塑料捕获有用波长范围内的光波，然后把电荷分离成电子和空穴，并且传输这些电荷，最后利用这些电荷做一些有用的事情。但进展太慢了。
Fred Wudl 在大会上发了言，他最先发明了可用于光电池的富勒烯/聚合物体系。似乎他偶然发明的这个体系难以被胜出，至少，同时在大会上发言的另一个人——哥德堡查尔姆斯理工大学的Mats Andersson是这样认为的。
以百分比表示的能量有效转化率仍然很低。最佳的效果是5%左右，这是在一个唯一的、仔细调制的样品上实现的——还远达不到实现所期望的可大规模工业化生产的印刷工艺的要求。要在现实生产中切实可行，体系需要达到10%的效率，或者，稍低于这个百分比也可以，但是需要研制出便宜的塑料，使其能以廉价的成本就可覆盖大片面积。到目前为止，尽管对上述体系中的聚合物做了大量修补，Anderson所能得到的最佳转化效率是2.8%。而来自弗吉尼亚工艺学校的Manpreet Kaur研制的体系仅实现了1%的转化效率。
上述体系的光电转化性能依赖于体系中聚合物的电子迁移性能和富勒烯基团的空穴（无电子）迁移性能。调整这一体系的主要途径是改变其中的聚合物基团。
不过，这一领域正在集聚力量。例如：Konarka 公司，它宣称自己在本年度末将可提供一种柔性的、高效的太阳能电池用塑料。对此，我们可以拭目以待。
这次年会当然产生了一些影响，但是我不禁认为低转化效率的情况将仍会持续一段时间。也许到明年，当 Konarka 公司的产品出来以后，学者们会与他们联手，一起寻找更为高效的体系。