包含石墨烯之高效率氧化鋅/有機混摻太陽能電池

Abstract

在科技快速發展且充滿能源及環境危機的時代，開發出有效且低成本的新能源是當務之急。而在近期研究的替代能源中，又以太陽能電池最受到大家的矚目。太陽能電池種類繁多，若是以材料來當作區分，可以分為:矽太陽能電池、無機化合物太陽能電池、染料敏化太陽能電池、有機太陽能電池等。其中以單晶矽太陽能電池的效率最高。但是因製造的成本高，不符合經濟效益，所以至今仍無法有效成為主要能源。而有機太陽能電池的優點在製作成本低，只需要用旋轉機便可以塗佈上作用層，再用加熱板加熱結晶。因其屬於低溫的製程，造價低廉，加上易於控制厚度，若是用於軟性塑膠機板上，變成可彎曲式的太陽能電池，十分有實用的價值。 此篇論文的主要研究，是以有機混合無機的太陽能電池。有機混無機的太陽 能電池製作方式，是先在清洗後的 ITO 玻璃基板上，用水熱法的方式，來長成柱狀的 ZnO，接著在旋轉塗佈上混和均勻的高分子混和均勻的 P3HT、PCBM，最後蒸鍍上銀電極。此種元件在本篇論文中為標準元件。我們發現到塗佈高分子主動層之前，先用旋轉塗佈的方式散布少許的graphene，可以有效的提高元件整體表現超過100%。 根據分析發現，元件效率的提升最主要的原因是藉由graphene在ZnO表面形成位能井的方法，給予電子明確的傳導路徑，使光電流與開路電壓大大的增加。根據實驗結果，電子可以更有效率的由高分子層傳遞到 ZnO 柱狀結構上進而更容易到達負極。依照此結論我們可以更進一步的製造出更有效率的有機太陽能電池。

At the time of high speed technology development, energy and environmental crisis, it is urgent to find effective and low-cost energy. Among all the recent researches for alternative energy, solar cell is one of the most noticeable devices. If we classify the type of solar cells, it can be discriminate as silicon solar cell, inorganic solar cell, dye sensitized solar cell and organic solar cell among of all these solar cells, the crystalline based solar cells have the highest efficiency. But, it still cannot become a major energy effectively because of its expensive manufacturing process and lacking economic benefits. In contrast, organic solar cells have a great advantage of low cost. It only needs a spin coater to fabricate the active layer and then annealed with a hotplate. According to its low cost, low temperature manufacturing process and easy thickness control, it would be practical to use them on flexible plastic board to make flexible solar cells. This thesis is mainly focused on the research of inorganic/organic hybrid solar cells. The inorganic/organic hybrid solar cells are made from ZnO rods and polymer P3HT/PCBM. After cleaning the ITO glass, ZnO rods were fabricated by the hydrothermal method, and then uniform P3HT/PCBM was spin coated on ZnO nano-rods. Finally, Ag electrode was evaporated for the measurement of photocurrent. The above-mentioned is called the standard device in this paper. We discover that distributing some graphene flakes on ZnO nanorod by spin coating graphene sol-gel before the fabrication of P3HT/PCBM layer can greatly improve the performance of solar cells by up to 100%. According to our study, the main reasons for the increased efficiency of solar cells can be attributed to large improvement in photocurrent and photovoltage caused by the direct electron path which is caused by functional graphene to form potential well on ZnO nanorod surface. As a result, charges can transfer from polymer blend to ZnO-nanorod more effectively and subsequently travel to electrodes leading to the improved performance in the photovoltaic devices.