具有半透明陰極之有機太陽能電池的光電特性研究

Research on Optical and Electrical Characteristics of Organic Photovoltaic Devices with Semitransparent Cathode

徐偉峰(Wei-Feng Xu)

指導教授 ： 李君浩

國立臺灣大學/電機資訊學院/光電工程學研究所/碩士(2009年)

https://doi.org/10.6342/NTU.2009.00919

摘要

在本論文中，我們根據copper phthalocyanine (CuPc) /fullerene (C60) /bathocuproine (BCP) 的異質接面結構製作了具有不同厚度的半透明銀陰極之有機太陽能電池。我們可以透過導電度和穿透度的比較來討論半透明銀薄膜的光電特性，而元件的電特性則由來自陽極或陰極端的照光分別被探討。藉由最佳化的金屬接觸(12.5 nm)，在可見光波長範圍的平均穿透度得到~32%，而分別來自陽極和陰極端的照光下功率轉換效率可以達到0.9%和0.29%。除此之外，藉由在薄陰極上加入有機的覆蓋層(40 nm的a-naphthylphenylbiphenyl diamine (NPB) )，在人眼視覺敏感的波長542 nm附近，最大穿透度可以增加到66.3%，而來自陰極端照射的功率轉換效率則提高到0.37%。除了元件受到垂直照光的討論外，斜向和漫射光效應對於半透明有機太陽能電池的效率也同樣被研究。
另一方面，為了讓最大的光強度朝在CuPc和C60之間的分離界面移動，我們調整有機吸收層的厚度來增加進入元件內的光子之吸收機率。在分別來自陽極和陰極端的照光下，具有最佳化的CuPc和C60厚度(20 nm/30 nm)之半透明元件可以達到1.22%和0.55%的高功率轉換效率。

關鍵字

有機太陽能電池 ； 半透明銀陰極 ； 穿透度

並列摘要

In this thesis, we demonstrated the organic photovoltaic (OPV) devices based on a copper phthalocyanine (CuPc) /fullerene (C60) /bathocuproine (BCP) hetero-junction structure with different thicknesses of Ag thin film as the semi-transparent cathode. The electrical and optical properties of the semi-transparent Ag films were discussed through the comparison of electrical conductivity and transparency. The electrical characteristics of the devices were compared under different side illuminated, from the anode side or the cathode side, respectively. By optimizing the thickness of metal contact (12.5 nm), we obtained the average transparency of ~32% over visible wavelength range and the power conversion efficiency (ηP) of 0.9% and 0.29% illuminated from the anode and cathode side, respectively. Moreover, the maximum transparency near 542 nm, which is sensitive to human eye, and ηP from top illumination can be increased up to 66.3% and 0.37%, respectively, by the introduction of organic capping layer (a-naphthylphenylbiphenyl diamine (NPB) = 40 nm) on top of thin cathode. In addition to the discussion of normal illumination, the effect of oblique and diffused light on the performance of semi-transparent OPV was also investigated.
On the other hand, we tuned the thicknesses of organic layers in order to shift the maximum intensity in optical field distribution toward the dissociation interface between CuPc/C60, which increased the absorption probability of a photon entering the semi-transparent OPV. The device with optimized thickness of CuPc and C60 (20 nm/30 nm) reached the high ηP of 1.22 % illuminated from the anode side and 0.55% illuminated from the cathode side.

並列關鍵字

Organic Photovoltaics (OPV) ； Semitransparent Ag cathode ； Transmittance

參考文獻

[1.1] M. A. Green, “Multiple band and impurity photovoltaic solar cell: General theory and comparison to tandem solar”, Progr. Photovoltaic, 9, 137 (2001).

[1.2] C. W. Tang, “Two-layer organic photovoltaic cell”, Appl. Phys. Lett., 48, 183 (1986).

[1.3] L. J. A. Koster, E. C. P. Smit, V. D. Mihailetchi, P. W. M. Blom, “Device model for the operation of polymer/fullerene bulk heterojunction solar cells”, Phys. Rev. B, 72, 085205 (2005).

[1.4] S. E. Shaheen, C. J. Brabec, N. S. Sariciftci, F. Padinger, T. Fromherz, J. C. Hummelen, “2.5% efficient organic plastic solar cells”, Appl. Phys. Lett., 78, 841 (2001).

[1.5] C. D. Dimitrakopoulos and D. J. Mascaro, “Organic thin-film transistors: A review of recent advances”, IBM J. Res. Dev., 45, 11 (2001).