Solution-processed nanocrystalline TiO₂ buffer layer used for improving the performance of organic photovoltaics

In this study, we use solution-processable crystalline TiO₂ nanoparticles as a buffer layer between the active layer and aluminum cathode to fabricate the P3HT:PCBM-based bulk heterojunction (BHJ) organic photovoltaic (OPV) devices. The employment of the presynthesized TiO₂ nanoparticles simplifies the fabrication of OPV devices because of the elimination of an additional hydrolysis step of precursors in air. The fabricated OPV devices with the thermally stable TiO₂ buffer layer are subjected to the further postdeposition thermal annealing, resulting in a power conversion efficiency (PCE) as high as 3.94%. The improved device performance could be attributed to the electron transporting and hole blocking capabilities due to the introduced TiO₂ buffer layer.