Enhanced performance of inverted organic photovoltaic cells using CNTs-TiOX nanocomposites as electron injection layer

• Published in: Nanotechnology 2013-09, Vol.24 (35)
• Main Authors: Zhang, Hong, Xu, Meifeng, Cui, Rongli, Guo, Xihong, Yang, Shangyuan, Liao, Liangsheng, Jia, Quanjie, Chen, Yu, Dong, Jinquan, Sun, Baoyun
• Format: Article
• Language: English
• Subjects: Applied sciences; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Electronics; Exact sciences and technology; Materials science; Molecular electronics, nanoelectronics; Nanocrystalline materials; Nanoscale materials and structures: fabrication and characterization; Nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals; Nanotubes; Physics; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Structure of solids and liquids; crystallography
• ISSN: 0957-4484; 1361-6528
• DOI: 10.1088/0957-4484/24/35/355401

In this study, we fabricated inverted organic photovoltaic cells with the structure ITO/carbon nanotubes (CNTs)-TiOX/P3HT:PCBM/MoO3/Al by spin casting CNTs-TiOX nanocomposite (CNTs-TiOX) as the electron injection layer onto ITO/glass substrates. The power conversion efficiency (PCE) of the 0.1 wt% single-walled nanotubes (SWNTs)-TiOX nanocomposite device was almost doubled compared with the TiOX device, but with increasing concentration of the incorporated SWNTs in the TiOX film, the performance of the devices appeared to decrease rapidly. Devices with multi-walled NTs in the TiOX film have a similar trend. This phenomenon mainly depends on the inherent physical and chemical characteristics of CNTs such as their high surface area, their electron-accepting properties and their excellent carrier mobility. However, with increasing concentration of CNTs, CNTs-TiOX current leakage pathways emerged and also a recombination of charges at the interfaces. In addition, there was a significant discovery. The incorporated CNTs were highly conducive to enhancing the degree of crystallinity and the ordered arrangement of the P3HT in the active layers, due to the intermolecular π-π stacking interactions between CNTs and P3HT.