Fabrication of optoelectronic devices relies on expensive, energy-consuming conventional tools including chemical vapor deposition, lithography, and metal evaporation. Furthermore, the films used in these devices are usually deposited at elevated temperatures (>300 ° C) and under high vacuum, which necessitate further restrictions on the device fabrication. Developing an alternative technology would contribute to the efforts on achieving a sustainable optoelectronics technology. Keeping this in our focus, here we present a simple technique to fabricate visible photodetectors (PDs). These fully solution-processed and transparent metal-semiconductor-metal (MSM) PDs employ silver nanowires (Ag NW) as the transparent electrodes replacing the indium-tin-oxide (ITO) commonly used in optoelectronic devices. By repeatedly spin coating Ag NWs on a glass substrate followed by the coating of zinc oxide nanoparticles, we obtained a highly conductive transparent electrode reaching a sheet resistance of 95 Ω / □ as measured by the four-probe method. Optical spectroscopy revealed that the transmittance of the Ag NW-ZnO films was 84% at 450 nm while the transmittance of the ITO films was 90% at the same wavelength. Following the formation of the conductive film, we scratched it using a heated surgical blade to open a gap. The scanning electron microscope images indicate that a gap of ∼30 μm is opened forming an insulating line. As the active layer, we drop-casted red-emitting CdSe/ZnS core-shell quantum dots (QDs) onto this gap to form a MSM PD. These visible QD-based PDs exhibited responsivities and detectivities up to 8.5 mA / W and 0.95 × 109 Jones, respectively at a bias voltage of 5 V and wavelength of 650 nm. These proof-of-concept PDs show that the environmentally friendly, low-cost, and energy-saving technique presented here can be an alternative to conventional, high-cost, and energy-hungry techniques while fabricating photoconductive devices.
Fabrication of optoelectronic devices relies on the expensive, energy-consuming conventional tools such as chemical vapor deposition, lithography, and metal evaporation. Furthermore, the films used in these devices are usually deposited at elevated temperatures and under vacuum that impose further restrictions to the device fabrication. Developing an alternative technology would contribute to the efforts on achieving a more sustainable optoelectronics technology. Keeping this focus in our focus, here we present a simple technique to fabricate visible photodetectors. These fully solutionprocessed and transparent metal-semiconductor-metal photodetectors employ silver nanowires (Ag NW) as the transparent electrodes replacing the indium-tin oxide (ITO) commonly used in optoelectronic devices. By repeatedly spin coating Ag NWs on a glass substrate followed by the coating of ZnO nanoparticles, we obtained a highly conductive transparent electrode reaching a sheet resistance of 95 Ω/□ as measured by the four-probe method. Optical spectroscopy revealed that the transmittance of the Ag NW-ZnO films was 84% at 450 nm while transmittance of the ITO films was 90% at same wavelength. Following the formation of the conductive film, we scratched it using a heated surgical blade to open a gap. The scanning electron microscope images indicate that a gap of ~30 mm is opened forming an insulating line. As the active layer, we drop-casted red-emitting CdSe/ZnS core-shell quantum dots (QDs) on to this gap to form a metal-semiconductor-metal photodetector. These visible QD-based photodetectors exhibited responsivities and detectivities up to 8.5 mA/W and 0.95x109 Jones, respectively. These proof-of-concept photodetectors show that the environmentally friendly, low-cost, and energy-saving technique presented here can be an alternative to conventional, more expensive, and energy-hungry techniques while fabricating lightharvesting devices.
We theoretically simulate the performance of ultranarrow emitters for the first time to achieve record high coverage for the International Telecommunication Union Radiocommunication Sector BT.2100 (Rec.2100) and National Television System Committee (NTSC) color gamut. Our results, employing more than 130-m parameter sets, include the investigation into peak emission wavelength and full width at half maximum (FWHM) values for three primaries that show ultranarrow emitters, i.e., nanoplatelets are potentially promising materials to fully cover the Rec.2100 color gamut. Using ultranarrow emitters having FWHM as low as 6 nm can provide the ability to attain 99.7% coverage area of the Rec.2100 color gamut as well as increasing the NTSC triangle to 133.7% with full coverage. The parameter set that provides possibility to fully reach Rec.2100 also has been shown to match with D65 white light by making use of the correct combination of those three primaries. Furthermore, we investigate the effect of the fourth color component on the CIE 1931 color space without sacrificing the achieved coverage percentages. The investigation into the fourth color component, cyan, is shown for the first time to enhance the Rec.2100 gamut area to 127.7% with 99.9% coverage. The fourth color component also provides an NTSC coverage ratio of 171.5%. The investigation into the potential of emitters with ultranarrow emission bandwidth holds great promise for future display applications.
Nanocomposites that incorporate TiO2 and ZnO nanoparticles separately in three-dimensional solgel matrices through full chemical integration are prepared to perform highly efficient photocatalytic activities for applications of environmental decontamination. Spectral responses of photocatalytic TiO2 and ZnO nanoparticles exposed to UV activation for self-cleaning process were obtained as also their optical relative spectral efficiency curves from 270 to 370 nm in the UV regime. Our investigations of the optimal conditions to increase their spectral photocatalytic efficiencies resulted in remarkably high levels of optical recovery and efficiency.
We review our research work on the development of photonic devices and systems embedded with nanocyrstals for new functionality within EU Phoremost Network of Excellence on nanophotonics. Here we report on CdSe/ZnS nanocrystal-based hybrid optoelectronic devices and systems used for scintillation to enhance optical detection and imaging in the ultraviolet range and for optical modulation via electric field dependent optical absorption and photoluminescence in the visible. In our collaboration with DYO, we also present photocatalytic TiO2 nanoparticles incorporated in solgel matrix that are optically activated in the ultraviolet for the purpose of self-cleaning.
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