Hybrid CNT-HfO2, Zno and Ag based Nanocomposites for Optoelectronic and Photovoltaic Applications

International audience; Hybrid nanocomposites containing Carbon nanotubes (CNT) and inorganic nanoparticles produce new properties due to interfacial effectsabsent in the individual nanomaterials. ZnO is a well-known semiconductor. Conversely, HfO2 is a wide bandgap dielectric. When reduced to nanoparticles with average sizes of 2.6nm, they emanate in the blue-green part of the visible spectrum. This is attributed to surface defects generated due to size reduction, which in turn create luminescent defect states within the band gap of HfO2. In both cases, i.e. ZnO and HfO2, the oxygen vacancy related emission is between 2.3 and 2.5eV. Both materials also emit at approximately 3.3eV. In ZnO, the emission at 3.27eV corresponds to the near band edge emission (NBE), while as in HfO2 it corresponds to the Hf3+ defects states. When combined with CNT, changes in the emission spectra are observed producing new phenomena. In the case of HfO2-CNT, both visible and UV photoexcitations are capable of producing a photocurrent at zero bias. This advocates its applicability as an active layer in photovoltaic cells. Depending on the photoexcitation, different defectstates participate in the generation of photocurrents. Furthermore, Ag nanoparticles can act as nano-antennas owing to their plasmonic effect and the addition of Ag nanoparticles to ZnO-CNT demonstrates that the optical bandgap of the nanocomposites increases due to the Burnstein-Moss effect. Thus,conjoining Ag to ZnO-CNT not only enhances the UV emission but also suppresses the visible emission. For highly defective ZnO, addition of Ag nanoparticles allows visiblelight activation of ZnO-CNT-Ag nanohybrids. This talk will cover the synthesis and optical properties of the nanohybrids.In addition, a modified common multimeter capable of measuring nanocurrents from HfO2-CNT will be briefly presented.