Spatial Homogeneity and Environmental Degradation Affected by Hole Transport Layers in Organic Solar Cells Organic photovoltaic cells (OPV) have received considerable attention as potential source of renewable energy for their advantages as easy fabrication, light weight, low manufacturing cost and mechanical flexibility. The improvement of device efficiency due to incorporation of a hole-transport layer (HTL) in bulk-heterojunction solar cells has been extensively reported. However, the most widely used HTL material, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is frequently suspected to be the dominating source for device’s instability under environmental conditions for its hygroscopic and acidic nature. And its colloidal nature is suspected to be responsible for spatial inhomogeneities and irreproducibility. Transition metal oxide (TMO) semiconductors are considered attractive alternative materials for the replacement of PEDOT:PSS. In this study, two different solution processed molybdenum trioxide (MoO3), obtained from two liquid precursors, incorporated as the HTL in OPV are demonstrated, one is quasi-continuous MoO3 with alcohol-based precursor solution and the other is a colloidal MoO3 with water-based precursor solution. |