在現今研究中，反相結構太陽能電池研究與應用越來越廣，本論文主要研究反相結構太陽能電池於軟性基板上，選擇不同電子傳輸層材料及製程，以期達到高效率及高穩定性的元件表現。
本研究使用P3HT(poly(3-hexythiophene))及PCBM([6,6]-phenyl C61-butyric acid methyl ester)混合製成塊材異質接面(bulk heterojunction)作為主動層；電子傳輸層分別使用碳酸銫(Cs2CO3)及氧化鋅(ZnO)；而電洞傳輸層則使用三氧化鉬(MoO3)。藉此些氧化物與電極接觸後產生電偶極 (Dipole)，進而調變陰陽極功函數使元件成為反相結構。
在旋轉塗佈碳酸銫薄膜做為電子傳輸層的元件研究中，經降低製程溫度以及降低旋轉塗佈轉速後，提升了元件的效率以及穩定性，目前最高效率可達2.2 %左右。而以ZnO薄膜所製出的反相結構太陽能電池，藉由改變ZnO沉積厚度，突破目前文獻所發表之元件表現，效率高達3.78 %。當提升沉積ZnO薄膜時的成長溫度後，效率再次提升至4.18 %，為當今最高效率之軟性反結構太陽能電池。證實了我們成功以低溫製程製作出高效率且高穩定度的軟性反結構太陽能電池。

Recently, inverted organic solar cells have been widely investigated since their life time is much longer than those of conventional ones. In this research, we prepared two different materials as electron transport layer and employed different fabrication methods to manufacture the inverted organic solar cell on flexible substrate.
In this work, an inverted organic solar cell based on P3HT:PCBM were spin-coated on two different electron transport layers which are cesium carbonate (Cs2CO3) and zinc oxide (ZnO) thin films. With these oxides, they changed the work function of ITO and metal electrode by forming a thin dipole layer.
In Cs2CO3 experiment series, we promoted the device performance and stability by reducing the annealing temperature and the spin rate of the Cs2CO3 layers. As a result, the power conversion efficiency (PCE) of the devices improved to 2.2%. In our main study, we changed the film thickness of ZnO. The devices exhibit a PCE of 3.78% with optimum film thickness. As deposition temperature of ZnO thin film increases from room temperature to 80oC, the PCE increases　from 3.78% to 4.18%, which is the highest performance for polymer solar cell on flexible substrates.

[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] J. 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] D. E. Carlson and C. R. Wronski, “Amorphous silicon solar cell,” Appl. Phys. Lett. 28, 671 (1976).
[4] K. Sriprapa and P. Sichanugrist, “High efficiency amorphous/microcrystalline silicon solar cell fabricated on metal substrate,” Photovoltaic Energy Conversion, 2003. Proceedings of 3rd World Conference on Volume 3, Page(s):2799 - 2800
(2003)
[5] 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).
[6] K. M. Coakley, and M. D. McGehee, “Conjugated polymer photovoltaic cells,”
Chem. Mater. 16, 4533, (2004)
[7] Harald Hoppe, and Niyazi Serdar Sariciftci,“Organic solar cell: An review,”J. Mater. Res., Vol. 19, No. 7, Jul (2004).
[8] 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).
[9] Bulent M. Basol, Vijay K. Kapur,” Flexible and light weight copper indium diselenide solar cells on polyimide substrates,” Solar Energy Materials & Solar Cells 43, 93-98 (1996).
[10] C. J. Brabec, F. Pandinger, “Realization of large area flexible fullerene- conjugate polymer photocells: a route to plastic solar cell,” Synthetic Metals 102, 861-864 (1999).
[11] M. Al-Ibrahim, H. K. Roth, and S. Sensfuss, Appl. Phys. Lett. 85, 1481 (2004).
[12] Jinsong Huang, Gang Li, and Yang Yang, “A Semi-transparent plastic solar cell fabricated by a lamination process,” Adv. Mater. 20, 415-419 (2008)
[13] Seok-In Na, Seok-Soon Kim, Jang Jo, and Dong-Yu Kim, “Efficient and flexible ITO-free organic solar cells using highly conductive polymer anodes,” Adv. Mater. 20, 1-7 (2008)
[14] Frederik C. Krebs, “All solution roll-to-roll processed polymer solar cells free from indium-tin-oxide and vacuum coating steps,” Organic Electronics, ORGELE 612, 8 April (2009)
[15] Mato Knez, Kornelius Nielsch, and Lauri Niinistö, “Synthesis and surface engineering of complex nanostructures by atomic layer deposition,” Adv. Mater. 19, 3425-3438 (2007).
[16] S. J. Lim, Soon-ju Kwon, and Hyungjun Kim, “High performance thin film transistor with low temperature atomic layer deposition nitrogen-doped ZnO,” Appl. Phys. Lett. 91, 183517 (2007).
[17] G. Li, V. Shrotriya, J. Huang, Y. Yao, T. Moriarty, K. Emery, and Y. Yang, Nat. Mater. 4, 864 (2005)
[18] G. Li, Y. Yao, H. Yang, V. Shrotriya, G. Yang, and Y. Yang, Adv. Funct. Mater. 17, 1636 (2007)
[19] C. Melzer, E. J. Koop, V. D. Mihailetchi, and P. W. M. Blom, Adv. Funct. Mater. 14, 865 (2004)
[20] G. Li, C.-W. Chu, V. Shrotriya, J. Huang, Y. Yang,“Efficient inverted solar cells,” Appl. Phys. Lett. 88, 253503 (2006).
[21] M. S. White, D. C. Olson, S. E. Shaheen, N. Kopidakis, and D. S. Ginley, “Inverted bilk-heterojunction organic photovoltaic device using a solution-derived ZnO underlayer,”Appl. Phys. Lett. 89, 143517 (2006).
[22] C. Waldaul, M. Morana, P. Denk, P. Schilinsky, K. Coakley, S. A. Choulis, and C. J. Brabec, Appl. Phys. Lett. 89, 233517 (2006).
[23] Hua-Hsien Liau, Li-Min Chen, Zheng Xu, Gang Li, and Yang Yang,“Highly efficient inverted polymer solar cell by low temperature annealing of Cs2CO3 interlayer,”Appl. Phys. Lett. 92, 173303 (2008).
[24] 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).
[25] R. Solanki, J. Huo, J. L. Freeouf, B. Miner, Appl. Phys. Lett. 81, 3864 (2002).
[26] M. S. Sander, M. J. Cote, W. Gu, B. M. Kile, C. P. Tripp, Adv. Mater. 16, 2052 (2004).
[27] W. J. Potscavage, S. Yoo, B. Domercq, and B. Kippelen, “Encapsulation of pentacene/C60 organic solar cells with Al2O3 deposited by atomic layer deposition,” Appl. Phys. Lett. 90, 253511 (2007).
[28] S.J. Lim, Soonju Kwon, H. Kim, “ZnO thin films prepared by atomic layer deposition and rf sputtering as an active layer for thin film transistor,” Thin Solid Films 516, 1523–1528 (2008).
[29] W. U. Huynh, J. J. Dittmer, N. Teclemariam, D. Milliron, and A. P. Alivisatos, K. W. J. Barnham, “Charge Transport in Hybrid Nanorod-Polymer Composite Photovoltaic Cells,” Phys. Rev. B 67, 115326 (2003).
[30] R.N. Marks, J.J.M. Halls, D.D.C. Bradley, R. H. Friend, A. B. Holmes, J. Phys.:Condens. Matter. 6, 1379 (1994)
[31] 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).
[32] 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.
[33] 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)
[34] 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).
[35] 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)
[36] 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)
[37] H. Hoppe, and N. S. Sariciftci, “ Organic solar cells: An overview,” J. Mater. Res. 19, 1924 (2004)
[38] 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).
[39] C. Waldauf, M. Morana, P. Denk, P. Schilinsky, K. Coakley, S. A. Choulis,a_ and C. J. Brabec, “Highly efficient inverted organic photovoltaics using solution based titanium oxide as electron selective contact,” Appl. Phys. Lett. 89, 233517 (2006).