RESUMEN
Nitrogen-doped carbon dots (NCDs), exhibiting strong yellow emission in aqueous solution and solid matrices, have been utilized for fabricating heterostructure white electroluminescence devices. These devices consist of nitrogen-doped carbon dots as an emissive layer sandwiched between an organic hole transport layer (PEDOT:PSS) and an array of rutile TiO2nanorods, acting as an electron transport layer. Under an applied forward bias of 5 V, the device exhibits broadband electroluminescence covering the wavelength range of 390-900 nm, resulting in pure white light emission characteristics at room temperature. The result demonstrates the successful fabrication of all solution-processed, low-cost, eco-friendly NCDs-based LEDs with CIE (Commission Internationale d'Éclairage) coordinate of (0.31, 0.34) and color rendering index (CRI) > 90, which are close to ideal white light emission characteristics. The device functionalities are achieved based on defect-related NIR emission from TiO2nanorods array and visible emission from nitrogen-doped carbon dots. This result paves a new opportunity to develop low-cost, solution-processed nitrogen-doped carbon dots based on warm White light emitting diodes with high CRI for large-area display and lighting applications.
RESUMEN
An ordered array of 1D ZnO nanorods obtained by colloidal templating is shown to dramatically enhance the sensing response of NO x at room temperature by confining light and creating periodic structures. The sensitivity is measured for a concentration varying from 2 to 10 ppm (response 53% at 10 ppm) at room temperature under white light illumination with ≈225 nm hole diameter. In contrast, structures with ≈450 nm hole size show better sensing under (response 98% at 10 ppm) elevated temperatures in dark conditions, which is attributed to the increased surface chemical interactions with NO x molecules due to the porous nature and enhanced accessible surface area of ZnO nanorods. Further, the decoration of ZnO Nanorods with gold nanoparticles shows enhanced sensor performance (response 130% at 10 ppm) due to localized surface plasmon resonance under white light illumination. The findings may lead to new opportunities in the visible light-activated room-temperature NO x sensors for healthcare applications.
RESUMEN
Nanopatterning of the active layer with feature size comparable to the wavelength of visible light is a popular strategy for improving the performance of optoelectronic devices, as these structures enhance the optical path length by light trapping due to combined contribution of multiple scattering, diffraction, and antireflection. Here, we report the fabrication of ZnO/CdS self-biased heterojunction photodetectors on soft lithographically patterned PEDOT:PSS layers with grating geometry. The present study combines the robustness of inorganic devices along with the convenience of easy patterning capability of an organic PEDOT:PSS layer. Patterns with two different line widths (L P = 350 nm, and Lp = 750 nm) have been used in this study to understand the influence of feature dimension on the device performance. We observe enhanced photoluminescence on patterned devices, in comparison to devices fabricated on flat PEDOT:PSS films, which is attributed to the increased interfacial area between the organic and inorganic layers. The spectral response [R( λ )] and specific detectivity [D * ( λ )] are found to be higher for the devices with Lp = 350 nm as compared to other devices due to enhanced absorption within the structures due to confinement of light, which also results in reduced reflectance in devices with Lp = 350 nm.
