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Annealing Effect of ZnO on the Performance of Inverted Organic Photovoltaic Devices

Wenjing Qin1,2), Guojing Ding1,2), Xinrui Xu1,2), Liying Yang1,2), Shougen Yin1,2)   

  1. 1) Key Laboratory of Display Materials & Photoelectric Devices (Ministry of Education) and School of Materials Science & Engineering, Tianjin University of Technology, Tianjin 300384, China
    2) Tianjin Key Lab for Photoelectric Materials & Devices, Tianjin 300384, China
  • Received:2012-10-31 Revised:2013-01-05 Online:2014-02-15 Published:2014-02-14
  • Contact: L. Yang,S. Yin
  • Supported by:

    The National Natural Science Foundation of China (Nos. 60876046 and 60976048), the Tianjin Natural Science Foundation (Nos. 13JCYBJC18900,13JCZDJC26700 and 12JCQNJC01300), the Scientific Developing Foundation of Tianjin Education Commission (No. 20100723), and the Tianjin Key Discipline of Material Physics and Chemistry.

Abstract:

ZnO nanoparticles films were prepared via sol–gel process and incorporated into inverted organic photovoltaic devices with a structure of ITO/ZnO/P3HT:PCBM/MoO3/Ag, in which ZnO film served as an electron selective layer. The effects of annealing temperature of ZnO film on the device performance were investigated. When the annealing temperature was 300 °C, a well-arranged ZnO thin film was obtained, and the optimized device had doubled short circuit current density (JSC) and seven-fold higher power conversion efficiency (PCE) compared to the devices without ZnO film. This improvement could be attributed to the enlarged interfacial area of ZnO/active layer and better energy band matching which causes an efficient electron extraction and a decreased interface energy barrier. At particularly high annealing temperature, dramatically increased sheet resistance of indium tin oxide (ITO) was found to cause PCE deterioration. Our finding indicates that it is highly important to investigate both morphology and electrical effects for understanding and optimizing organic photovoltaic (OPV) performance.

Key words: ZnO, Inverted organic photovoltaic, Annealing effect