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標題: | 有機太陽能電池奈米尺度形貌之研究 Nanoscale Morphology of Organic Solar Cells |
作者: | Chih-Cheng Lin 林志誠 |
指導教授: | 陳俊維(Chun-Wei Chen) |
關鍵字: | 有機太陽能電池,電場處理,二氧化鈦奈米晶體尺寸,石墨烯電極, Organic solar cell,electric field-assisted annealing,TiO2 nanocrystal dimensionality,graphene electrode, |
出版年 : | 2012 |
學位: | 博士 |
摘要: | 摘要
於本研究中,我們首先探討於溶劑揮發成膜過程中同時施加直流電場並且不進行任何元件熱後處理方式對於共軛高分子聚(3-己基噻吩):富勒烯衍生物[6,6]-苯基-C61-丁酸甲酯混摻有機太陽能電池之影響。在共軛高分子成膜過程中,施加電場有助於高分子本身結構自組裝排列,進而將元件效率提升至4.1 %。由低掠角入射X光繞射實驗結果說明電場處理有助於形成聚(3-己基噻吩)薄層及垂直結晶排列,以至於提升載子傳輸及元件效率。然而電場處理對於聚(3-己基噻吩): [6,6]-苯基-C61-丁酸甲酯混摻系統之影響主要歸因於內部溶劑電偶極距與外部施加電場相互作用所造成。此方法可整合成大面積和低溫製成方式對於將來可撓曲式有機太陽能電池有著莫大的影響。 我們也嘗試利用低掠角入射X光繞射實驗以及電子斷層顯像去探討混摻不同奈米晶體尺寸對共軛高分子聚(3-己基噻吩)奈米尺度形貌之變化。更利用多重尺度coarse-grained molecular dynamics模擬去建構聚(3-己基噻吩):二氧化鈦奈米粒子或奈米柱混摻系統之形貌而進一步解釋實驗結果。且由共軛高分子形貌及二氧化鈦奈米晶體尺寸之關係得知,混摻系統中沿著平行與垂直基板方向有著顯著的光學吸收及載子傳輸差異,此實驗結果對於有機無機混摻電子元件未來發展提供了決定性的訊息。此外我們同樣發現到,雖然嘗試施加電場處理於有機/無機混摻系統中對聚(3-己基噻吩)本身結構自組裝排列影響不大,但卻有助於改善具非等方向性之二氧化鈦奈米柱於混摻薄膜中的均勻分散性,進而造成電子遷移率上升。 最後我們成功地證明將光電元件及光感測器製作在石墨烯穿透電極上,有助於增加無機硫化鉛吸光層於紅外光範圍之吸收。由於石墨烯電極相較於氧化銦錫電極具有較高的紅外光穿透度,儘管石墨烯電極有較高的片電阻值,以石墨烯為穿透電極之硫化鉛元件仍具有較高的紅外光反應。進而說明以石墨烯為穿透電極元件之顯著紅外光特性使其對於未來太陽能電池,紅外光顯影感測及光通訊等應用具有極大的前瞻性。 Abstract In this study, we first have demonstrated a simple annealing method to fabricate the polymer solar cells based on poly(3-hexylthiophene) (P3HT) and fullerene derivative phenyl-C61-butyric acid methyl ester (PCBM) blends by applying a DC electric field during the solvent-drying process without any thermal post-treatment. The applied electric fields assist the self-organization of polymer during film formation as a result of enhanced polymer chain ordering, giving a power conversion efficiency (PCE) up to 4.1 %. The grazing incidence X-ray diffraction (GIXRD) measurement suggests that the electric field-assisted annealing will facilitate the crystallization of P3HT in both lamellar stacking and vertical stacking as a result of improved carrier transport and photovoltaic performance. It is also concluded that the effect of electric field-assisted annealing on the P3HT:PCBM hybrids is mainly attributed to the electric dipole moment of the solvent interacting with the external electric field. This method can be easily integrated to large-area and low-temperature fabrication processes for the development of flexible polymer solar cells. We also demonstrate the dependence of nanocrystal dimensionality and organization on the polymer nanomorphology in P3HT:TiO2 nanocrystal hybrids which were revealed by electron tomography and grazing-incidence X-ray-diffraction (GIXRD) using a synchrotron X-ray beam respectively. We further performed a multiscale molecular dynamic simulation to understand the morphological orientation of polymer blended with TiO2 nanoparticles (NPs) or nanorods (NRs). The correlation between polymer nanoscale morphology and nanocrystal dimensionality and anisotropy in P3HT:TiO2 nanocrystal hybrids explains the observed different optical absorption and carrier transport behaviors perpendicular or parallel to the film substrates. Our results provide the crucial information for the future development of organic/inorganic hybrid electronic devices such as thin film transistors (TFTs) or photovoltaics (PVs). In addition, we also find that although applied electric field on the organic/inorganic hybrids cannot greatly assist the self-organization of P3HT, but it promotes the homogeneous distribution of anisotropic TiO2 nanorods in polymer matrix, further resulting in an increase in electron mobility. Finally, we successfully demonstrate an enhancement of infrared light harvesting of inorganic PbS nanocrystal photovoltaic and photodetector devices based on the transparent graphene electrode. Due to high infrared transparency of the graphene electrode with respect to indium tin oxide (ITO), the infrared photoresponse of the graphene-based device is superior to the ITO-based counterpart, in spite of a higher sheet resistance of the graphene electrode. The outstanding infrared characteristics of the devices based on the graphene electrode make it a promising candidate for infrared optoelectronic applications such as solar cells, imaging and sensing, or optical communication. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/16357 |
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顯示於系所單位: | 材料科學與工程學系 |
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