Reduced Recombination by Fullerene Composited Metal Oxide as Electron Extraction Layers for Hybrid Optoelectronic Devices

The performance of solar cells and photodetectors based on metal oxide/conjugated polymer hybrids was significantly enhanced by embedding fullerene (C60) in the metal oxide of TiO2. With the TiO2–C60 bulk composites as electron extraction layers, photodetectors based on poly(3-hexylthiophene) (P3HT)/TiO2–C60 hybrids exhibited the highest detectivity of 6.54 × 1012 jones at 520 nm and a fast response with the shortest rise time of 32 us. The key role of the C60 in the TiO2 layer is causing a fast electron transfer from defect state excitons to C60, resulting in the suppression of the recombination of the defect state excitons produced by a fluorescence (Föster) resonance energy transfer process from photoinduced P3HT excitons to the TiO2 defect states.