In this work, gold nanoparticle/graphene oxide (AuNP/GO) nanocomposites are synthesized and used as anodic buffer layers in organic photovoltaic devices (OPVs). The application of thiol-terminated polyethylene glycol as a capping agent prevents the aggregation of AuNPs on the GO surface and further improves the solubility and stability of these nanomaterials in solutions. When AuNP/GO nanomaterials served as the buffer layers, they introduced localized surface plasmon resonance (LSPR) in the OPVs, leading to noticeable enhancements in the photocurrent and the efficiencies of the OPVs. We attribute the primary origin of the improvement in device performance to local field enhancement induced by the LSPR. We anticipate that this study might open up new avenues for constructing plasmon-enhancing layers on the nanoscale to improve the performance of solar cells.
Significant advances have been made in the development of plasmonic devices in the past decade. Plasmonic nanolasers, which display interesting properties, have come to play an important role in biomedicine, chemical sensors, information technology, and optical integrated circuits. However, nanoscale plasmonic devices, particularly those operating in the ultraviolet regime, are extremely sensitive to the metal and interface quality. Thus, these factors have a significant bearing on the development of ultraviolet plasmonic devices. Here, by addressing these material-related issues, we demonstrate a low-threshold, high-characteristic-temperature metal-oxide-semiconductor ZnO nanolaser that operates at room temperature. The template for the ZnO nanowires consists of a flat single-crystalline Al film grown by molecular beam epitaxy and an ultrasmooth Al2O3 spacer layer synthesized by atomic layer deposition. By effectively reducing the surface plasmon scattering and metal intrinsic absorption losses, the high-quality metal film and the sharp interfaces formed between the layers boost the device performance. This work should pave the way for the use of ultraviolet plasmonic nanolasers and related devices in a wider range of applications.
Graphene, with cracks filled with gold nanoparticles, is grown by chemical vapor deposition on a Cu substrate. The crack-filled graphene not only exhibits superior electrical properties but also forms a better junction with other semiconductors. A high-quality crack-filled graphene/Si Schottky junction solar cell is achieved, demonstrating the highest fill factor (0.79) and best efficiency (12.3%).
Cationic iridium complexes incorporated 4,5-diaza-9,9'-spirobifluorene as N(∧)N ancillary ligands, in which one (2) or two (3) phenyl groups were introduced onto 4,5-diazafluorene to afford intraligand π-π interactions. The X-ray crystal structures of complexes 2 and 3 show that the pendant phenyl ring forms strong intramolecular face-to-face π-stacking with the difluorophenyl ring of the cyclometalated ligand with distances of 3.38 Å for complex 2 and 3.40 and 3.46 Å for complex 3. This π-π stacking interaction minimizes the expansion of the metal-ligand bonds in the excited state, resulting in a longer device lifetime in the light-emitting electrochemical cell (LEC) devices.
Efficient phosphorescent sensitized white light-emitting electrochemical cells (LECs) based on a blueemitting phosphorescent cationic transition metal complex (CTMC) doped with a red-emitting fluorescent dye are demonstrated. Blue phosphorescence and phosphorescence-sensitized red fluorescence contribute to white emission. Furthermore, the microcavity effect of the device structure is utilized to suppress the green part of the electroluminescence (EL) spectrum of the blue-emitting phosphorescent metal complex (1) via destructive interference. Hence, more saturated blue EL emission can be obtained. When combined with saturated red emission, white EL emission with Commission Internationale de l'Eclairage coordinates approaching (0.33, 0.33) can be obtained without the need for saturated deep-blue emitting CTMCs. Peak external quantum efficiency and power efficiency of the phosphorescence sensitized white LECs are up to 7.9% and 15.6 lm W À1 , respectively. These efficiencies are among the highest reported for white LECs and reveal that phosphorescent sensitization is useful for improving device efficiencies of white LECs.
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