本研究是探討以電紡製備高孔隙度聚偏二氟乙烯共六氟丙烯(Polyviny lidenefluoride-co-hexafluoropropylene, PVDF-HFP)高分子薄膜,輔以大氣電漿改質製程對染料敏化太陽能電池效能之影響。研究分為兩部份,第一部份是利用實驗設計法(二水準部分因子設計)找出電紡纖維膜之最適化參數,其變因為溶液濃度、噴嘴至收集板距離、電壓及溶液流速;第二部份是利用電漿來探討最佳改質條件,分為純氬氣系統和氬氣添加甲烷系統兩類,其探討參數為電漿功率、處理時間、氣體流率與噴頭至基材距離,並利用水滴接觸角判斷其改質效果,及以氬氣電漿誘導接枝丙烯酸,其固定參數在濃度10%,溫度是50 ℃,接枝時間3 h。最後將膜材作為染料敏化太陽能電池之半固態電解質,並組成電池測其效率。 實驗結果顯示PVDF-HFP膜材經氬氣或氬氣加甲烷電漿改質後,水滴接觸角從136°各降至26°及19°,而經X射線光電子能譜儀(XPS)和傅立葉紅外線光譜儀(FTIR)分析也發現各接上C-O及C=O含氧官能基,即表面性質由疏水性變為超親水性。經由膜材老化實驗得知其親水性可以維持至少36 h和72 h。而在場發射電子顯微鏡(FE-SEM)分析下觀察到PVDF- HFP薄膜在經由電漿改質後,在低倍率放大下膜材表面雖然無明顯變化,但從高倍率放大則發現纖維表面由平滑變為粗糙面。在電池阻抗分析中,我們發現以氬氣電漿改質之PVDF- HFP薄膜電解質阻抗從15.9Ω減少到10.3 Ω,氬氣加甲烷電漿改質則為11.9 Ω。而在AM 1.5之規格下,自製PVDF- HFP電紡膜之光電轉換效率為3.39%,經氬氣改質後之電解質其光電轉換效率可提升至4.04%,液態光電轉換效率為4.31%。經改質後之PVDF-HFP高分子電解質在黑暗儲存循環的長時間測試360 h後,發現其確實可延長電池壽命及穩定性,其壽命約為液態電解質之2倍。
The study aims to explore the influences of fabricating PVDF-HFP (Polyviny lidenefluoride-co- hexafluoropropylene) membranes on the performance of dye-sensitized solar cells by electrospunning and atmospheric plasma modification process. This research is divided into two parts which are to develop optimization parameters of electrospun fiber membranes and to explore the best conditions by plasma modification, which is also divided into two kinds: pure argon and argon added methane systems. Finally, cell is assembled to measure photovoltaic efficiency. The parameters of the electrospinning including solution of concentration, the distance between nozzle and collection plate, voltage, and solution of flow rate are discussed in this study, thus, the Experimental Design (Two level fractional factorial designs) was implemented to find out the optimization parameters. The plasma parameters accordingly plasma power, treatment time, gas flow rate, and the distance between nozzle and substrate are mainly focused on the plasma modification. Also, the water contact angle was used to determine the effect of modification. The experimental results suggest that by the plasma of PVDF-HFP membrane modification, its water contact angle decreased from 136 degrees down to 19 degrees. In other words, the nature of the hydrophobic surface turned into a super-hydrophilic membrane which could be maintained for 36 hours by the aging test. And the ionic conductivity increased from 7.10×10-3 S/cm to 2.13×10-2 S/cm. On the other hand, at AM1.5 and 100mW/cm2 of the light intensity, the photoelectric conversion efficiency of self-made electrospun PVDF-HFP membrane was 3.39%. The photoelectric conversion efficiency of plasma modification by argon gas could be increased to 4.04%, and photoelectric conversion efficiency of liquid was 4.31%. Also, at-rest stability of the quasi-solid-state DSSC was found to decrease hardly by 30% at room temperature. In contrast, the DSSC with a liquid electrolyte showed a decrease of about 50% at room temperature.