利用電調制技術與光調制技術研究有機太陽能電池能帶及載子的行為

Electrical and Light Modulated Technique Analysis in Organic Solar Cell

吳兆權(Chao-Chuan Wu)

指導教授 ： 陳俊維

國立臺灣大學/工學院/材料科學與工程學研究所/碩士(2013年)

https://doi.org/10.6342/NTU.2013.02009

摘要

電化學交流阻抗分析技術是一個方便可以量測元件電性的技術。利用Bisquert的等效電路模型模擬，可以得到元件中載子的動態行為的訊息-載子的生命週期、載子遷移率。Mott-Schottky分析則可以得到半導體與金屬能帶的相關訊息。這篇研究中所量測的元件為有機太陽能電池，其結構組成為ITO/PEDOT:PSS/P3HT:PCBM/Al.，利用了上述這兩種技術分析了有機太陽能電池元件在主動層P3HT:PCBM及金屬鋁之間形成 Schottky barrier的內建電場以及載子在元件中傳輸的動態行為。在之前的實驗室的研究中，我們合成出不同氧鈦比的TiOx膜且鑑定其能帶位置，利用旋鍍法將不同氧鈦比的TiOx鍍膜在主動層與金屬陰極之間當作電子傳輸層，且發現太陽能電池的效率以及Voc會因為不同氧鈦比的TiOx而有所不同。在此篇研究中，我們利用Mott-Schottky分析及Bisquert等效電路模擬的交流阻抗分析了元件的能帶彎曲及載子動態行為說明了這些現象。
在第二部分，我們展示了光調制技術LPT(photoelectric light pulse technique)，以調制光激發元件去量測其所造成的光電流去看元件在不同電壓下空間電荷(space charge)的變化。此結果可以與利用調制電技術的Mott-Schottky分析相比較，我們用了不同種元件來驗證結果。

關鍵字

Mott-Schottky ； 有機太陽能電池 ； TiOx ； 光調制技術

並列摘要

Electrichemical impedance analysis is a convenient technique to acquire the information about electric property of devices. After fitting with Bisquert model of equivalent circuit, we can acquire the carrier dynamic behavior such as mobility and lifetime of devices. And Mott-Schottky analysis can acquire the information about energy band bending. In this study, we use these techniques to analyze the built in voltage (Vbi) and carrier dynamic behaviors in organic photovoltaic. The structure of organic photovoltaic is: ITO/PEDOT:PSS/P3HT:PCBM/Al. There is a formation of a Schottky junction at active layer (P3HT:PCBM) and Al contact. In previous study, we spin coat different ratio TiOx on active layer and discover that the device efficiency and Voc would change depend on the ratio of TiOx. In this study, we can explain the phenomena by Mott Schottky analysis and EIS analysis. And the influences of carrier dynamic behavior also be shown.
The second part, we present photoelectric light pulse technique method to compare with Mott-Schottky analysis. The photo u-v technique use space charge concept shows the similar result to measure Vbi with Mott-Schottky analysis which use the capacitance concept. We demo several device to show the result is compatible.

並列關鍵字

Mott-Schottky ； organic solar cell ； TiOx ； LPT

參考文獻

1. Osborne, M., Heliatek's organic tandem solar cell verified at 10.7% record conversion efficiency. PVTech, 2012.

2. Da Costa, P.G. and E. Conwell, Excitons and the band gap in poly (phenylene vinylene). Physical Review B, 1993. 48(3).

3. Coakley, K.M. and M.D. McGehee, Conjugated polymer photovoltaic cells. Chemistry of Materials, 2004. 16(23): p. 4533-4542.

4. Ma, W., et al., Thermally stable, efficient polymer solar cells with nanoscale control of the interpenetrating network morphology. Advanced Functional Materials, 2005. 15(10): p. 1617-1622.

5. Li, G., et al., “Solvent Annealing” Effect in Polymer Solar Cells Based on Poly (3‐hexylthiophene) and Methanofullerenes. Advanced functional materials, 2007. 17(10): p. 1636-1644.