近年來因為能源的問題日益嚴重，替代能源的發展逐漸成為全球各國重視的議題。現今太陽能電池發展備受矚目，有機太陽能電池具有低成本、可撓性、輕便易攜、簡單製程步驟等優勢，未來極具潛力運用於商業用途。製程的簡化尤為重要，期以成本降低、製程迅速等有利因素，幫助有機太陽能電池發展。
本研究以簡單反式結構有機太陽能電池，使用溶液製程，主動層材料選用塊材異質接面(bulk heterojunction, BHJ)系統，本研究中主動層材料選擇上，主要為P3HT(poly(3-hexythiophene))及PCBM([6,6]-phenyl C61-butyric acid methyl ester)混合，溶劑使用為鄰-二氯苯(DCB)，並由此延伸嘗試不同的主動層與電洞傳輸層材料。然利用照光後，本研究結構ITO/P3HT：PCBM/PEDOT:PSS/Ag之元件能量轉換效率由0.89%可提升至4.06%(AM1.5G 100 mW/cm2)。由X-Ray光電子能譜分析顯示在主動層表面有更多的成分聚集於介面，主動層材料分佈變化的結果與元件的電流密度-電壓量測相關，造成元件的特性表現提升。其元件特性為不可逆現象，且相較於標準元件有更優異的生命期維持元件效率。由研究結果顯示，此連續照光效應可運用於不同的主動層材料系統，藉此可製程更簡單且更低廉的有機太陽電池元件。

In recent years, the problem of non-renewable energy resource is becoming more serious. As a result, governments around the world at the moment pay much more attention to the development of alternative energy. Now, the organic solar cells is noted for mechanical flexibility, light weight, especially its simple and low-cost manufacturing. Those potential have made organic solar cells more promising in commercial applications.
In this work, we report an inverted organic solar cells which required no electron selective layer were fabricated. The active layer was a bulk heterojunction (BHJ) consisting of blending of poly(3-hexylthiophene)(P3HT) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) in 1, 2-Dichlorobenzene. We found that ITO/P3HT：PCBM/PEDOT:PSS/Ag device improved the PCE from 0.89% to 4.06%(AM1.5G 100 mW/cm2). X-Ray photoelectron spectroscopy revealed further segregation in surface composition at the interface and the result were correlated to the current density-voltage measurement. We also extend this work to study a variety of materials as active and hole-transport layers in the inverted solar cells.
The light soaked device were found the improvement irreversibly and excellent performance work in lifetime compared to conventional device. As a result, light soaking could be a cost-effective method to achieve efficient inverted organic solar cells.

[1] D. M. Chapin, C. S. Fuller, and G.L. Pearson, “A New Silicon pn Junction Photocell for Converting Solar Radiation into Electrical Power,” J. Appl. Phys. 25, 676 (1954).
[2] Zhao, A. Wang, and M. A. Green, “24.5% efficiency silicon PERT cells on MCZ substrates and 24.7% efficiency PERL cells on FZ substrates,” Prog. Photovolt. : Res. Appl. 7, 471 (1999).
[3] KRI Report No.8：Solar Cells, February 2005
[4] M. A. Contreras, B. Egaas, K. Ramanathan, J. Hiltner, A. Swartzlander, F. Hason, and R. Noufi, “Properties of 19.2% efficiency ZnO/CdS/CuInGaSe2 thin-film solar cells,” Prog. Photovolt.: Res. Appl. 7, 311 (1999).
[5] K. M. Coakley,Wudl and M. D. McGehee,“Conjugated polymer photovoltaic cells,” Chem. Mater. 16, 4533 (2004).
[6] Harald Hoppe, and Niyazi Serdar Sariciftci,“Organic solar cell: An review,”J. Mater. Res., Vol. 19, No. 7, Jul 2004.
[7] Kyungkon Kim, Jiwen Liu, Manoj A. G. Namboothiry, and David L. Carroll, “Roles of donor and acceptor nanodomains in 6% efficient thermally annealed polymer photovoltaics,” Appl. Phys. Lett. 90, 163511 (2007).
[8] C. W. Tang, “Two-layer organic photovoltaic cell,” Appl. Phys. Lett. 48, 183
(1986)
[9] B. O’Regan and M. A. Grätzel, “A low cost, high efficiency solar cell based on
dye-sensitized colloidal TiO2 films,” p Nature 353, 737 (1991).
[10] G. Yu, K. Pakbaz, and A. J. Heeger, “Semiconducting polymer diodes: Large size low cost photodetectors with excellent visible-ultraviolet sensitivity,” Appl. Phys. Lett. 64, 3422 (1994).
[11] W. Ma, C. Yang, X. Gong, K. Lee, and A. J. Heeger, Adv. Funct. Mater. 15, 1617 (2005)
[12] Hsiang-Yu Chen, Jianhui Hou1, Shaoqing Zhang, Yongye Liang, Guanwen Yang, Yang Yang, Luping Yu3, YueWu1 and Gang Li,” Polymer
solar cells with enhanced open-circuit voltage and efficiency,” Nature Photonics 3, 649 - 653 (2009)
[13] G. Li, V. Shrotriya, J. Huang, Y. Yao, T. Moriarty, K. Emery, and Y. Yang, Nat. Mater. 4, 864 (2005).
[14] G. Li, Y. Yao, H. Yang, V. Shrotriya, G. Yang, and Y. Yang, Adv. Funct. Mater. 17, 1636 (2007).
[15] C. Melzer, E. J. Koop, V. D. Mihailetchi, and P. W. M. Blom, Adv. Funct. Mater. 14, 865 (2004).
[16] G. Li, C.-W. Chu, V. Shrotriya, J. Huang, Y. Yang, “Efficient inverted solar cells,” Appl. Phys. Lett. 88, 253503 (2006).
[17] C. Waldaulf, M. Morana, P. Denk, P. Schilinsky, K. Coakley, S. A. Choulis, and C. J. Brabec, Appl. Phys. Lett. 89, 233517 (2006).
[18] Takayuki Kuwabara, Taketoshi Nakayama, Konosuke Uozumi, Takahiro Yamaguchi, Kohshin Takahashi, “Highly durable inverted-type organic solar cell using amorphous titanium oxide as electron collection electrode inserted between ITO and organic layer” Solar Energy Materials & Solar Cells 92 (2008) 1476– 1482
[19] Steven K. Hau, Hin-Lap Yip, Nam Seob Baek, Jingyu Zou, Kevin O’Malley,and
Alex K.-Y. Jen , “Air-stable inverted flexible polymer solar cells using zinc oxide nanoparticles as an electron selective layer”,Appl. Phys. Lett. 92, 253301 (2008)
[20] R.N. Marks, J.J.M. Halls, D.D.C. Bradley, R. H. Friend, A. B. Holmes, J. Phys.:Condens. Matter. 6, 1379 (1994)
[21] C. J. Brabec, A. Cravino, D. Meissner, N. S. Sariciftci, M.T. Rispens, L. Sanchez, J. C. Hummelen, and T Fromherz, “ The influence of materials work function on the open circuit voltage of plastic solar cells,” Thin Solid Film, 403-404,368 (2002).
[22] H. Kim, S-H. Jin, H. Suh, and K. Lee, “Origin of the open circuit voltage in conjugated polymer-fullerene photovoltaic cells,” In Organic Photovoltaics IV, edited by Z.H. Kafafi, and P.A. Lane, Proceedings of the SPIE, Vol. 5215, (SPIE, Bellingham, WA, 2004), p. 111.
[23] C. J. Brabec, S. E. Shaheen, C. Winder, and N. S. Sariciftci, “Effect of LiF/metal electrodes on the performance of plastic solar cells,” Appl. Phys. Lett. 80, 1288 (2002)
[24] H. Sirringhaus, P. J. Brown, R. H. Friend, M. M. Nielsen, K. Bechgaard, B. M. W. Langeveld-Voss, A. J. H. Spiering, R. A. J. Janssen, E. W. Meijer, P. Herwig, and D. M. De Leeuw, “ Two-dimensional charge transport in self-organized, high-mobility conjugated polymers,” Nature, 401, 685 (1999).
[25] Yongye Liang, Danqin Feng, Yue Wu, Szu-Ting Tsai, Gang Li, Claire Ray and Luping Yu “Highly Efficient Solar Cell Polymers Developed via Fine-Tuning of Structural and Electronic Properties” J. Am. Chem. Soc., 2009, 131 (22), pp 7792–7799
[26] Yongye Liang, Zheng Xu, Jiangbin Xia, Szu-Ting Tsai, Yue Wu, Gang Li, Claire Ray, Luping Yu, “For the Bright Future—Bulk Heterojunction Polymer Solar Cells with Power Conversion Efficiency of 7.4%” Adv. Mater. 2010, 22, 1–4.
[27] J. C. Hummelen, B. W. Knight, F. Lepeq, F. Wudl, J. Yao, and C. L. Wilkins, “Preparation and Characterization of Fulleroid and Methanofullerene Derivatives,” J.Org. Chem. 60, 532 (1995)
[28] E. J. Meijer, D. M. de Leeuw, S. Setayesh, E. V. Veenendaal, B. H. Huisman, P. W. M. Blom, J. C. Hummelen, U. Scherf, T. M. Klapwijk. Nat. Mater. 2, 678 (2003)
[29] Jen-Hsien Huang, Chuan-Pei Lee, Zhong-Yo Ho, Dhananjay Kekuda, Chih-Wei Chu and Kuo-Chuan Ho, “Enhanced spectral response in polymer bulk heterojunction solar cells by using active materials with complementary spectra” Solar Energy Materials & Solar Cells 94 (2010) 22–28.
[30] K. J. Reynolds, J. A. Barker, N. C. Greenham, R.H. Friend, and G. L. Frey,“Inorganic solution-processed hole-injecting and electron-blocking layers in polymer light-emitting diodes,”J. Appl. Phys. Vol. 92, No. 12, 15 December 2002.
[31] Jinsong Huang, Gang Li, and Yang Yang, “A Semi-transparent Plastic Solar Cell Fabricated by a Lamination Process,” Adv. Mater. 2008, 20, 415–419.
[32] H. Schmidt, K. Zilberberg, S. Schmale, H. Flügge,T. Riedl,and W. Kowalsky, “Transient characteristics of inverted polymer solar cells using titaniumoxide interlayers”,Appl. Phys. Lett. 96, 243305 (2010)
[33] Yinhua Zhou, Hyeunseok Cheun, Willliam J. Potscavage, Jr, Canek Fuentes-Hernandez, Sung-Jin Kim and Bernard Kippelen “Inverted organic solar cells with ITO electrodes modified with an ultrathin Al2O3 buffer layer deposited by atomic layer deposition” J. Mater. Chem., 2010, 20, 6189-6194
[34] M. T. Lloyd, D. C. Olson, P. Lu, E. Fang, D. L. Moore, M. S. White,M. O. Reese, D. S.GinleyandJ. W.P.Hsu, J.Mater.Chem., 2009, 19, 7638.
[35] Jianchang Guo, Yongye Liang, Jodi Szarko, Byeongdu Lee, Hae Jung Son, Brian S. Rolczynski, Luping Yu, and Lin X. Chen, “Structure, Dynamics, and Power Conversion Efficiency Correlations in a New Low Bandgap Polymer: PCBM Solar Cell” J. Phys. Chem. B 2010, 114, 742–748.