美國麻省理工學(xué)院(MIT)的研究人員們正致力于打造出世界上最輕薄的太陽能電池設(shè)計，并期望以此推動太陽能電池研究的另一個新發(fā)展方向。 根據(jù)研究人員們表示，盡管目前的太陽能電池設(shè)計多半追求以最低的成本實現(xiàn)高轉(zhuǎn)換效率，然而卻常忽略了在輕薄尺寸方面的要求。然而，對于行動電子設(shè)備而言，輕與薄一向是最主要的設(shè)計目標(biāo)，而太陽能電池設(shè)計一向強(qiáng)調(diào)的是高轉(zhuǎn)換效率。 如今，根據(jù)MIT表示，既輕且薄的太陽能電池設(shè)計，在航空、太空等應(yīng)用以及運(yùn)輸成本高的偏遠(yuǎn)地區(qū)已經(jīng)越來越受歡迎了。未來，隨著材料變得越來越稀少，采用超輕薄太陽能電池可實現(xiàn)對于自然資源的保護(hù)，甚至能降低安裝成本。 MIT教授Jeffrey Grossman：“至于如何才可能成為最薄的太陽電池呢？我們的預(yù)測是只用兩層材料的電池設(shè)計。”Jeffrey Grossman與博士后研究員Marco Bernardi，以及羅馬大學(xué)客座研究員Maurizia Palummo共同合作進(jìn)行這項研究。 Grossman進(jìn)一步解釋，“目前的確有許多應(yīng)用都必須考慮到重量，因此盡可能采用最薄的主動層材料以及最小化封裝，從而帶來更薄、更耐用的基板，那么最終將改變整個安裝方式。此外，這還大助于解決一個核心問題：我們究竟能從特定材料的每個原子或鍵結(jié)中省下多少功耗？”

MIT研究人員用電腦模擬各種不同材料，以期找到最輕薄的太陽能電池組合。
Source：MIThi9esmc

MIT估計，其超薄型太陽能電池薄膜──基本上是厚度約1納米的2D薄層──比傳統(tǒng)太陽能電池更節(jié)能1,000倍以上。但其缺點是效率較低，且需要較現(xiàn)有太陽能電池更多10倍的面積，才能產(chǎn)生相同量的能量，因為超薄太陽能電池效率約為2%，而傳統(tǒng)太陽能電池(PC)則可實現(xiàn)高達(dá)20%的效率。然而，研究人員已經(jīng)計劃采用堆疊超薄2D太陽能電池的層狀結(jié)構(gòu)，以提高其效率。 Grossman說：“我們預(yù)測的兩層堆疊可能達(dá)到1-2%的效率，但當(dāng)然也可能堆疊到兩層以上，因而能提高效率。由2D材料制作的電池效率應(yīng)該也能達(dá)到像目前‘傳統(tǒng)’ PV約10-20%的效率?！? 研究人員們?nèi)栽谀M原型設(shè)計所用的超薄太陽能電池材料。透過精密的模擬過程，各種拓?fù)浣Y(jié)構(gòu)的層疊片材使用了原子石墨烯薄膜、二硫化鉬與二硒化物。這些設(shè)計的優(yōu)點在于不僅較傳統(tǒng)太陽能電池更具輕薄的優(yōu)勢，同時也不受氧化、紫外線輻射和環(huán)境中水分的影響──這三者通常是傳統(tǒng)太陽能電池長期穩(wěn)定性的殺手。此外，相較于傳統(tǒng)PV安裝，由于新式超薄設(shè)計不需采用玻璃罩或冷卻安裝，因而可節(jié)省一半以上的成本。 Bernardi說：“超輕薄太陽能電池可望降低安裝成本。目前基于硅晶的太陽能電池模組已經(jīng)很重了，加上保護(hù)玻璃后更重。目前太陽能電池陣列占整個安裝成本的60%，主要都是由于重量造成的。因此，為了實現(xiàn)更輕的太陽能電池，我們期望能找到一種超輕薄的機(jī)械可撓性材料，使其可用塑料封裝來取代玻璃材料，以便為太陽能電池安裝建立新方向?！? 相較于傳統(tǒng)太陽能電池，超薄太陽能電池的材料成本可望大幅降低。但研究人員還未能在實驗室中建立這一原型，因而也無法讓材料實現(xiàn)量產(chǎn)。接下來，研究人員們打算開始在實驗室針對各種不同的材料配方與堆疊結(jié)構(gòu)測量其效率與長期穩(wěn)定性。 本文授權(quán)編譯自EE Times，版權(quán)所有，謝絕轉(zhuǎn)載 編譯：Susan Hong 參考英文原文：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.