One-step in situ hydrothermal fabrication of D/A poly(3-hexylthiophene)/TiO2 hybrid nanowires and its application in photovoltaic devices†
Abstract
In this study, we developed a novel in situ hydrothermal method to fabricate self-assembled P3HT/TiO2 hybrid nanowires, wherein a facile one-step synthetic strategy was utilized to co-organize P3HT molecules and titanium precursors into highly elongated hybrid nanowires, followed by a hydrothermal process in an autoclave to in situ transform the titanium precursors into crystalline TiO2 nanoparticles on the P3HT nanofibrils. P3HT nanofibrils were utilized as a structure-directing motif to achieve a favorable dispersion of electron acceptor (A) TiO2 nanocrystals of 10–15 nm in diameter embossed along the nanofibrils, as well as an efficient electron donor (D) for the nanohybrid. In particular, the crystallization temperature of anatase-phase TiO2 nanoparticles with high crystallinity obtained via the hydrothermal method was significantly reduced to 130 °C in an elevated pressure of ∼7 bars as compared to the conventional calcination temperature of 450 °C at ambient pressure for TiO2 nanocrystal synthesis, therefore, allowing the synergistic one-step fabrication of both highly crystalline TiO2 nanoparticles embossed on highly crystalline long-range ordered P3HT nanofibrils. As a consequence of the structural development, this P3HT/TiO2 embossed nanohybrid could afford significant improvements in its D/A interfacial contact area for effective charge separation without the need for capping ligands typically used in ex situ D/A blend systems, as well as an efficient pathway for charge transport, leading to enhanced optoelectronic properties and device performance. The highest conversion efficiency of 0.14% was presented by the P3HT/TiO2 embossed hybrid device, which was a remarkable improvement as compared to only 0.03% from an ex situ P3HT/TiO2 hybrid device. This novel in situ approach shows a feasible way to fabricate organic/inorganic nanohybrid materials of conjugated copolymers with different inorganic nanoparticles for the applications of future optoelectronic devices.
- This article is part of the themed collection: 2015 Journal of Materials Chemistry A Hot Papers