Wet-milled anatase titanium oxide nanoparticles as a buffer layer for air-stable bulk heterojunction solar cells

Abstract

In this study, an air-stable bulk heterojunction organic solar cell demonstrated by utilization of titanium oxide (TiO2) nanoparticles as a hole blocking layer was prepared through high-energy grinding method. The large clumps of the anatase TiO2 underwent deaggregation to form a stable dispersed solution during the grinding process. The resultant suspension can form a uniform and smooth TiO2 film through spin coating on various substrates. Because of substantial oxygen and water protection effect of TiO2 thin film, the bulk heterojunction solar cells exhibit a significant long-term stability. It is also found that the cell performance can be promoted dramatically after ultraviolet activation. The mechanism responsible for the enhanced cell efficiency was also investigated. This solution-based method does not require surfactants, thus preserving the intrinsic electronic and optical properties of TiO2 that makes these proposed buffer layers quite attractive for next-generation flexible devices appealing high conductivity and transparency. Copyright (c) 2014 John Wiley & Sons, Ltd.