- 學位論文
傳統有機高分子太陽能電池的準確測量方法及使用氧化鋅的倒置結構有機高分子太陽能電池之研究
Methods of accurate measurement of conventional polymer solar cells and study of zinc oxide based inverted polymer solar cells
摘要
本論文的研究分成兩個部份。第一部份探討有機高分子太陽能電池準確測量轉換效率的方法，並同時針對元件效率的提升提出改進的方法。第二部份探討如何在poly(3-alkylthiophene) (P3HT)/[6,6]-phenyl-C61-butyric acid methyl ester (PCBM)的表面上，使用溶膠凝膠的方法製作出鈦的氧化物薄膜。 針對第一部份，本論文分別製作傳統有機高分子太陽能電池和倒置結構有機高分子太陽能電池。在傳統有機高分子太陽能電池裡，我們特別著重於探討Poly(3,4-ethylene dioxythiophene): poly(styrene sulfonate) (PEDOT:PSS)經由dimethyl sulfoxide (DMSO)處理後對其元件效率的影響。PEDOT:PSS的薄膜導電度因DMSO處理而提高，使得薄膜導電度從0.12 S/cm提升到464.7 S/cm。但是實驗上發現使用了DMSO提升導電度PEDOT:PSS的元件，短路電流竟然高達35.5 mA/cm2。進一步研究發現指出，這些不合理的電流是由於高導電度PEDOT:PSS於有效面積之外不當的收集。因此，本論文証實在傳統有機高分子太陽能電池在測量效率的準確度和高導電度的PEDOT:PSS有關，必需再針對光源加以校正測量才可以得出準確的元件效率。而在倒置結構的有機高分子太陽能電池裡，我們分別製作氧化鋅薄膜和氧化鋅奈米柱兩種不同結構的太陽能電池。實驗上發現使用氧化鋅薄膜的元件和氧化鋅奈米柱的元件，在元件效率上皆因擺放在空氣中而逐漸增加。同時我們也發現到，使用氧化鋅奈米柱並沒有幫助到整體的元件效率提升。在大氣之下，使用氧化鋅薄膜的元件，於第六天達到最高的效率3.6%。而使用氧化鋅奈米柱的元件較氧化鋅薄膜元件較差，於第五天達到最高的效率2.9%。 針對第二部份，本論文利用溶膠凝膠的方式，於P3HT/PCBM的表面旋轉塗佈製作非結晶的鈦氧化物(amorphous titanium oxide, TiOx)薄膜。我們分別混合搭配使用乙二醇單甲醚、異丙醇和正己烷當作溶劑配製TiOx旋塗溶液，實驗上發現不同的溶劑會造成不同表面形態的TiOx薄膜。在這些溶劑選擇當中，使用乙二醇單甲醚和正己烷的混合溶劑所製作出來的TiOx薄膜最為平坦。所以在P3HT/PCBM上使用旋轉塗佈法製作TiOx薄膜時，乙二醇單甲醚和正己烷的混合溶劑是最佳的TiOx旋塗溶液配方。
並列摘要
The research in this thesis can be separted into two parts. In the first part, methods of accurate measurement and improving the power conversion efficinecy of polymer solar cells are discussed. In the second part, sol-gel deposition of amorphous titanium oxide thin film on the poly(3-alkylthiophene) (P3HT)/ [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) substrate is demonstrated. In the first part, polymer-based organic solar cells with conventional and inverted structure are fabricated. For the converntional structure, the relationship between the performance and dimethyl sulfoxide (DMSO) modified poly(3,4-ethylene dioxythiophene): poly(styrene sulfonate) (PEDOT:PSS) of polymer solar cells is investigated. The PEDOT:PSS is modified by adding DMSO into its aqueous solution, resulting in the enhancement of conductivity from 0.12 S/cm to 464.7 S/cm. However, the device with DMSO modified PEDOT:PSS has a short circuit current density of 35.5 mA/cm2, which is not physically possible. The unreasonable current density results form the improper collection by the extremely condutive DMSO modified PEDOT:PSS. We demonstrate that the performance is strongly related to the employment of modified PEDOT:PSS and it can be corrected by strict definition of illumination area while measuring. For the inverted structure, the polymer solar cells based on the zinc oxide (ZnO) thin film and ZnO nanorod are investigated. Interestingly, we find that the enhancement in the device performance can be achieved by placing the devices in the air. Meanwhile, we also find that the use of ZnO nanorod may be not a rewarding method for enhancing efficiency of the polymer solar cells. With placement and measurement in the air, our inverted polymer solar cells based on ZnO thin film and ZnO nanorod show efficiency of 3.6% at 6th day and 2.9% at 5th day without encapsulation. In the second part, sol-gel preparation of amorphous titanium oxide (TiOx) films with distinct morphological properties on the P3HT/PCBM coated substrate is obtained by solution spin coating. The TiOx film is deposited by three precursors using 2-methoxyethanol, isopropanol and mixture of 2-methoxyethanol and hexane as solvents. We demonstrate that the morphology of TiOx film is related to the employment of dissimilar solvent. TiOx film obtained from mixed 2-methoxyethanol/hexane is a superior choice for the preparation of TiOx on P3HT/PCBM substrate because of its good smoothness.