Effect of TiO₂ nanoparticles on polymer-based bulk heterojunction solar cells

This work addresses the enhanced power conversion efficiency η of a hybrid organic solar cell in which the active layer comprises poly(3-hexylthiophene) (P3HT), [6,6]-phenyl-C₆₁ -butyric acid methyl ester (PCBM), and titanium dioxide (TiO₂) nanoparticles. Under the illumination, the open circuit voltage increases, the fill factor is improved and the series resistance reduces as the concentration of TiO₂ nanoparticles increases. Highly refractive TiO₂ nanoparticles are assumed to promote the internal trapping of photons by scattering (redirecting) the light reflected from the metallic electrode in the active layer. The transport of charge carriers through the active layer is also improved due to the formation of TiO₂ nanoparticles/Al interfaces. η is doubled and the short circuit current is maximized by optimizing the blending concentration of TiO₂ nanoparticles.