PbS-quantum-dots/double-wall-carbon-nanotubes nanohybrid based photodetectors with extremely fast response and high responsivity

Here, we report on the use of the pulsed laser deposition (PLD) technique to decorate double-wall carbon nanotubes (DWCNTs) with PbS quantum dots (QDs) forming thus a new class of physically synthesized nanohybrid (NH) materials, without resorting to any chemical functionalization and/or post processing. By integrating these novel DWCNTs/PbS-QDs nanohybrids into microfabricated photodetectors, we were able to demonstrate, for the first time, not only responsivities as high as 230 A W−1 (at an applied voltage of only 5 V), but also the fastest response time (of 30 μs) ever reported on carbon nanotubes and/or QDs based photodetectors. The very high responsivity of our PLD synthesized NHs is due to the synergetic contributions of both multiple exciton generation occurring in the PbS-QDs and the very efficient charge transfer from the QDs to the high mobility DWCNTs. Such a rapid charge transfer will significantly lower the transit time of the majority generated photocarriers, which in turn contributes to the occurrence of photoconductive gain in these NHs-based photodetectors. These results, clearly demonstrate the potential of the PLD technique for the physical synthesis of nanohybrids exhibiting unprecedented photoresponsive properties.