Remarkably enhanced red-NIR broad spectral absorption via gold nanoparticles: applications for organic photosensitive diodes.

For organic films, remarkably enhanced red-NIR broad spectral absorption was achieved via the incorporation of gold nanoparticles (AuNPs) using a simple and facile preparation. The relevant thermal evaporation method has produced size-controllable AuNPs in the range of 0-20 nm diameter. The potential use of localized surface plasmon resonance (LSPR) enhanced organic photosensitive diodes (OPDs) as sensitive broadband sensors was discussed in this context. Here we showed that, by combining organic heterojunctions with size-controllable plasmonic AuNPs, the efficiency of organic photodetectors could be increased by up to one order of magnitude, because of LSPR and scattering effects of the AuNPs. Fabricated OPD devices showed a large photoresponse under radiation from wavelengths between 650 and 830 nm, accompanied by a low power consumption profile. A schematic energy level model combined with theoretical simulation analysis was proposed to explain the experimental data. More importantly, to the best of our knowledge, this work demonstrated the broadest photosensitivity with high responsivity from AuNP-based photodetectors, proving the potential of AuNPs as a promising material for efficient optoelectronic devices.