Performance Improvement of Bulk Heterojunction Polymer Solar Cells with Metal Oxide Nanoparticles

Polymer solar cells (PSC) based on bulk heterojunction (BHJ) materials containing conjugated polymers and fullerene derivatives have large advantages of easy fabrication, and also have considerable potential in renewable energy resources [1–3]. The polymer solar cell efficiencies and their lifetimes can be improved by using metal oxides such as titanium suboxide TiOx or zinc oxide [4].  

In this study, we fabricated polymer solar cells with two different bulk heterojunction (BHJ), thieno(3,4-b)-thiophene/ benzodithiophene copolymer,(6,6)-phenyl C₇₁ butyric acid methyl ester (PTB7/PC₇₁BM), poly (3- hexylthiophene) and [6,6]-phenylC₇₁butyric acid methyl ester (P3HT/PC₇₁BM). For the two PSC devices the TiO_x interlayer was inserted between the active layer (BHJ) and metal electrode. The performance enhancement of the devices with and without interlayer was investigated. X-ray diffraction (XRD) and UV-VIS measurements were used to investigate structural and optical properties of samples. The current–voltage (J-V) curves of the polymer solar cells with active area of ~ 10 mm² were measured. We found that the TiO_x layer improved the efficiency and stability of the devices compared with the same devices without TiO_x interlayer. Also we observed that the PTB7/PC₇₁BM/TiO_x solar cell was much stable compared with P3HT/PC₇₁BM/TiO_x solar cell.

References:

[1] Y. Lu, C. Alexander, Z. Xiao, Y. Yuan, R. Zhang and J. Huang, Nanotechnology, 23, 2012, 344007.

[2] H. Sun, J. Weickert, H. C. Hesse, L. S.-Mende, Solar Energy Materials & Solar Cells, 95, 2011, 3450–3454.

[3] A. R. b. M. Yusoff, H. P. Kim, J. Jang, Organic Electronics, 14, 2013, 858–861.  

[4] J. K. Lee, N. E. Coates, S. Cho, N. S. Cho, D. Moses, G. C. Bazan, K. Lee, and A. J. Heeger, Appl. Phys. Lett, 92, 2008, 243308.