Dissimilar mechanism of executing hole transfer by WO3 and MoO3 nanoparticles in organic solar cells

We investigated the effect of metal oxide nanoparticles (NPs) in poly (3,4 ethylenedioxythiophence): poly (styrene-sulfonate) layer for the light harvestation in poly (3-hexylthiophene):[6,6]-pheny-C-61-butyric acid methyl ester organic solar cells. The role of tungsten trioxide nanoparticles (WO3) and molybdenum trioxide nanoparticles (MoO3) inenhancing the efficiency of solar cells was compared. Due to the difference in the energy band structure of the two nanoparticles, the WO3 NPs acted as a hole blocking layer, whereas MoO3 NPs helped in the hole transfer. The solar cell with WO3 NPs at 1.5 wt% concentration showed a power conversion efficiency of 4.22% under AM 1.5G illumination and the device blended with 2 wt% of MoO3 NPs showed a power conversion efficiency of 4.40%. We measured various electrical properties including, electrochemical impedance spectroscopy and recombination mechanisms using the light intensity dependent current-voltage measurement of organic solar cell. (C) 2014 Elsevier B.V. All rights reserved.