利用超寬頻激發探測光譜研究 PCPDTBT：PCBM 太陽能電池材料之載子超快動力學

Ultrafast carrier dynamics of PCPDTBT：PCBM studied by ultrabroadband pump-probe spectroscopy

黃書琪(Shu-Chi Huang)

指導教授 ： 籔下篤史

國立交通大學/理學院/電子物理系所/碩士(2020年)

摘要

與傳統的矽太陽能電池相比，近年研究被受關注的光伏有機聚合物太陽能電池具有多重優勢：製作成本低廉、機械可撓性、可調電子能帶。有機聚合物中，近年的新興材料：聚[2,1,3-苯並噻二唑-4,7-二基[4,4-雙(2-乙基己基)-4H-環戊並[2,1-B:3,4-B']二噻吩-2,6-二基]] (PCPDTBT)與[6,6]苯基C61丁酸甲酯 (PC61BM)混和成薄膜有良好的轉換效率。然而PCPDTBT：PCBM 的薄膜組成會影響能量轉換效率，例如溶劑使用、組成比例、薄膜厚度等因素將影響轉換效率，目前原因尚不明瞭。
本論文透過自行架設的NOPA (non-collinear optical parametric amplifier非共線光參數放大器) 系統的小於10飛秒脈衝的可見光探測解析PCPDTBT與PCPDTBT：PCBM 薄膜分子內部超快動力學情形、時間與薄膜內部呈現的缺陷密度，期許提供相關技術或是材料的重要訊息。以波段 (511~755奈米) 所偵測到超快動態反應清晰完整的紀錄，進而計算其生命週期與相應的衰減相關光譜 (DAS)。藉由速率方程式的求解，針對衰減相關光譜計算與中間狀態相對應的演化關聯光譜 (EAS)，同時也說明了PCPDTBT和PCPDTBT：PCBM薄膜的主要反應過程。

關鍵字

PCPDTBT ； 有機太陽能電池 ； 高分子聚合物 ； 超寬頻激發探測 ； 超快動力學

並列摘要

Organic solar cell using photovoltaic polymer has many advantages compared with traditional crystal silicon solar cell such as low production cost, mechanical flexibility, adjustable chemical parameter modified by side chain. Among photovoltaic polymers, poly[2,6-(4,4-bis-(2-ethlhexyl)-4H-cyclopenta [2,1-b;3,4-b']dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT) was recently reported to have high power conversion efficiency (PCE) when it is formed to be a thin film mixed with [6,6]-phenyl-C61-butyric acid methyl ester (C61-PCBM). Formation and morphology of the PCPDTBT：PCBM thin films seriously affect the power conversion efficiency (PCE) . However, the detail mechanism causing the differences is still unknown.
In the present work, we have performed ultrafast transient absorption spectroscopy of PCPDTBT and PCPDTBT：PCBM thin films by using a sub-10fs broadband visible laser pulse from a homemade NOPA (non-collinear optical parametric amplifier) system. The measured transient absorption traces in the broad probe wavelength region extending from 511 to 755 nm were analyzed by global fitting analysis to estimate lifetimes and their corresponding decay associated spectra. Solving the rate equation, evolution associated spectra (EAS) corresponding to intermediate states were calculated from the decay associated spectra. Pump power dependence of EAS has assigned the estimated lifetimes to their corresponding relaxation process elucidating the primary reaction process in the PCPDTBT and PCPDTBT：PCBM thin films.

並列關鍵字

PCPDTBT ； organic solar cell ； polymer ； ultrabroadband pump-probe spectroscopy ； ultrafast

參考文獻

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