"Fabrication and Characterization of Novel Inverted Organic Solar Cells Employing ZnO ETL and MoO_3 HTLFabrication and Characterization of Novel Inverted Organic Solar Cells Employing ZnO ETL and MoO_3 HTL"

Abstract

This paper presents with an efficiency (η 1.93%) inverted organic photovoltaic devices based on a P3HT: PCBM bulk heterojunction (BHJ) with a highly transparent sol-gel derived Zinc oxide (ZnO) film as electron selective layer and Molybdenum trioxide (MoO3) as hole selective layer. Moreover, the MoO3 layer prevents damage to the organic active materials due to the ITO sputtering process. ZnO nanoparticle films with different thicknesses are deposited on the transparent electrodes as a nano-porous electron-selective contact layer. A thin silver (Ag) film is used between the BHJ photoactive layer and a P3HT: PCBM, which improves the wettability and significantly enhances the stability of the device (>50 days of air exposure). Photovoltaic device parameters such as short circuit current density (Jsc), open circuit voltage (Voc), Fill-Factor (FF), efficiency (η), series and shunt resistances (Rs & Rsh) are systematically examined for inverted devices. These results are important for development of organic solar cells and point out the role of contact layers, in particular, ZnO conductivity and morphology in the device performance.