Efficiency Enhancement of Inverted Orfanic Photovoltaic Cells with High Aspect Ratio ITO Electrode

Abstract

We demonstrate inverted organic photovoltaic cells in which nano-patterned ITO electrodes was extended deep within active layer, providing efficient electron transport pathway. The height and diameter of cylinder pattern of ITO electrode fabricated by Second Scattering Lithography(SSL) are 100nm and 400nm respectively. Titanium oxide was uniformly deposited on nano-patterned ITO electrodes by atomic layer deposition(ALD) characterized by excellent conformality on 3-dimensional structure. Since the conduction band of TiO2 is similar to that of PCBM, electrons can transport to ITO electrode with ease. Therefore, the performance of inverted organic photovoltaic cells ,which are based on the regioregular poly(3-hexythiophene) and C61 butyric acid methyl ester bulk heterojunction, can be dramatically improved by both shorter traveling distance for electron and the special functional layer of TiO2.