麻省理工学院致力开发最轻薄的太阳能电池

美国麻省理工学院(MIT)的研究人员们正致力于打造出世界上最轻薄的太阳能电池设计，并期望以此推动太阳能电池研究的另一个新发展方向。 根据研究人员们表示，尽管目前的太阳能电池设计多半追求以最低的成本实现高转换效率，然而却常忽略了在轻薄尺寸方面的要求。然而，对于行动电子设备而言，轻与薄一向是最主要的设计目标，而太阳能电池设计一向强调的是高转换效率。 如今，根据MIT表示，既轻且薄的太阳能电池设计，在航空、太空等应用以及运输成本高的偏远地区已经越来越受欢迎了。未来，随着材料变得越来越稀少，采用超轻薄太阳能电池可实现对于自然资源的保护，甚至能降低安装成本。 MIT教授Jeffrey Grossman：“至于如何才可能成为最薄的太阳电池呢？我们的预测是只用两层材料的电池设计。”Jeffrey Grossman与博士后研究员Marco Bernardi，以及罗马大学客座研究员Maurizia Palummo共同合作进行这项研究。 Grossman进一步解释，“目前的确有许多应用都必须考虑到重量，因此尽可能采用最薄的主动层材料以及最小化封装，从而带来更薄、更耐用的基板，那么最终将改变整个安装方式。此外，这还大助于解决一个核心问题：我们究竟能从特定材料的每个原子或键结中省下多少功耗？”

MIT研究人员用电脑模拟各种不同材料，以期找到最轻薄的太阳能电池组合。
Source：MIT3snesmc

MIT估计，其超薄型太阳能电池薄膜──基本上是厚度约1纳米的2D薄层──比传统太阳能电池更节能1,000倍以上。但其缺点是效率较低，且需要较现有太阳能电池更多10倍的面积，才能产生相同量的能量，因为超薄太阳能电池效率约为2%，而传统太阳能电池(PC)则可实现高达20%的效率。然而，研究人员已经计划采用堆叠超薄2D太阳能电池的层状结构，以提高其效率。 Grossman说：“我们预测的两层堆叠可能达到1-2%的效率，但当然也可能堆叠到两层以上，因而能提高效率。由2D材料制作的电池效率应该也能达到像目前‘传统’ PV约10-20%的效率。” 研究人员们仍在模拟原型设计所用的超薄太阳能电池材料。透过精密的模拟过程，各种拓扑结构的层叠片材使用了原子石墨烯薄膜、二硫化钼与二硒化物。这些设计的优点在于不仅较传统太阳能电池更具轻薄的优势，同时也不受氧化、紫外线辐射和环境中水分的影响──这三者通常是传统太阳能电池长期稳定性的杀手。此外，相较于传统PV安装，由于新式超薄设计不需采用玻璃罩或冷却安装，因而可节省一半以上的成本。 Bernardi说：“超轻薄太阳能电池可望降低安装成本。目前基于硅晶的太阳能电池模组已经很重了，加上保护玻璃后更重。目前太阳能电池阵列占整个安装成本的60%，主要都是由于重量造成的。因此，为了实现更轻的太阳能电池，我们期望能找到一种超轻薄的机械可挠性材料，使其可用塑料封装来取代玻璃材料，以便为太阳能电池安装建立新方向。” 相较于传统太阳能电池，超薄太阳能电池的材料成本可望大幅降低。但研究人员还未能在实验室中建立这一原型，因而也无法让材料实现量产。接下来，研究人员们打算开始在实验室针对各种不同的材料配方与堆叠结构测量其效率与长期稳定性。 本文授权编译自EE Times，版权所有，谢绝转载 编译：Susan Hong 参考英文原文：MIT Aims for Thinner Solar Cells，by R. Colin Johnson

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{pagination} MIT Aims for Thinner Solar Cells R. Colin Johnson PORTLAND, Ore. — Solar cell designs today pursue performance at the lowest possible cost, neglecting the dimensions of thin-and-lightweight, according to Massachusetts Institute of Technology (MIT) researchers who aim to design the world's thinnest solar cells. For mobile electronics, thin-and-lightweight are prime design goals, but solar cells have aimed instead at the highest efficiency. Today, making solar cells thinner and lighter would be welcome for applications in aviation, space exploration, and in remote areas where transportation costs are high, according to MIT. In the future, as materials become more scarce, the conservation achieved with ultra-thin solar cells could cost-reduce even urban installations. "Our predictions are for what may very well be the thinnest solar cells possible, ones out of only two layers of materials," professor Jeffrey Grossman told EE Times. Grossman performed the work with post-doctorate researcher Marco Bernardi and Maurizia Palummo, a visiting researcher from the University of Rome. "There are indeed applications where weight is crucial, where the thinnest possible amount of active layer material with minimal encapsulation may change the installation game, because it could get us onto [thinner, more durable] substrates," Grossman said. "In addition, this gets to the heart of what I think is an important question: namely, what is the most power we can squeeze out of each and every atom or bond of a given material?" MIT researchers use computer simulations to shuffle through different materials in the search for the thinnest possible solar cells. (Source: MIT) MIT estimates that its ultra-thin solar cell films -- essentially two-dimensional (2D) layers as thin as one nanometer -- can deliver 1,000 times more energy-per-pound than conventional solar cells. The tradeoff is that their efficiency is lower, requiring about 10 times the area of a conventional solar cell to produce the same amount of energy, since ultra-thin solar cells have an efficiency of up to 2 percent, compared with up to 20 percent for conventional photovoltaic (PV) solar cells. However, the researchers have plans for stacking the ultra-thin 2D solar cells in layered structures to improve their efficiency. "These two-sheet stacks we predict could have efficiencies of 1 to 2 percent. However, it is certainly possible to make stacks that consist of more than just two layers, and in that case the efficiency would go up," said Grossman. "There is no reason efficiencies of cells made from 2D materials couldn't be just as efficient as current 'traditional' PV -- in the 10 to 20 percent range." The ultra-thin solar cell design is still in simulation while the researchers decide which material to use for prototypes. In detailed simulations, various topologies of stacked sheets use atomically thin graphene, molybdenum-disulfide, and molybdenum-diselenide. The best of these designs not only provide a weight advantage over conventional solar cells, but are also immune to oxygen, ultraviolet radiation, and moisture in the environment -- the three killers of long-term stability in conventional solar cells -- giving the new ultra-thin designs the additional advantage of eliminating the need for glass covers or standoff mounting, which consumes over half the cost of conventional PV installations. "Ultralight solar cells (with extremely high power/weight in our case) have the potential to reduce installation costs. Current solar modules based on silicon are heavy and made heavier by the glass protecting them. Their installation amounts to 60 percent of the total cost of a solar array, largely due to the high weight," said Bernardi. "By finding ultra-thin and mechanically flexible materials, the hope is to make very light solar cells, which can be encapsulated with plastics rather than glass, and hence create new paradigms for photovoltaic installation." The material cost for ultra-thin solar cells would be minimal, compared to conventional solar cells, but the researchers have yet to create prototypes in the lab or to work on making the materials manufacturable in high volume. Next they plan to test their formulations in the lab by measuring the efficiency and long-term stability of various formulations and stacking structures.