Quantum dots show great promise for fabrication of hybrid bulk heterojunction solar cells with enhanced power conversion efficiency, yet controlling the morphology and interface structure on the nanometer length scale is challenging. Here, we demonstrate quantum dot-based hybrid solar cells with improved electronic interaction between donor and acceptor components, resulting in significant improvement in short-circuit current and open-circuit voltage. CdS quantum dots were bound onto crystalline P3HT nanowires through solvent-assisted grafting and ligand exchange, leading to controlled organic-inorganic phase separation and an improved maximum power conversion efficiency of 4.1% under AM 1.5 solar illumination. Our approach can be applied to a wide range of quantum dots and polymer hybrids and is compatible with solution processing, thereby offering a general scheme for improving the efficiency of nanocrystal hybrid solar cells.
200 - nm -thick BMN films were deposited on Pt∕TiO2∕SiO2∕Si and Cu∕Ti∕SiO2∕Si substrates at various temperatures by pulsed laser deposition. The dielectric constant and capacitance density of the films deposited on Pt and Cu electrodes show similar tendency with increasing deposition temperature. On the other hand, dielectric loss of the films deposited on Cu electrode varies from 0.7% to 1.3%, while dielectric loss of films on Pt constantly shows 0.2% even though the deposition temperature increases. The low value of breakdown strength in BMN films on Pt compared to films deposited on Cu electrode was attributed to the increase of surface roughness by the formation of secondary phases at interface between BMN films and Pt electrodes.
Layer transfer via ion-cut has been developed for GaN to fabricate multiple templates from a high-quality GaN wafer without compromising the crystallinity. Here, we report on the successful fabrication of 4-in. layer-transferred GaN on sapphire. A high quality epitaxial layer is also successfully grown despite the structural degradation in the transferred layer by hydrogen implantation. Fully packaged vertical light-emitting diodes grown on the template exhibit the peak external quantum efficiency of 48.6% and optical output power of 1.8 W at 220 A/cm2, suggesting that the template could serve as a low-cost substrate for high-performance nitride devices.
Various bismuth-based pyrochlore films were deposited on copper clad laminate substrates at temperatures below 150 °C by pulsed laser deposition for embedded capacitor applications. The films showed smooth and dense morphologies during deposition at room temperature. Bi2Mg2/3Nb4/3O7 (BMN) pyrochlore films showed the most stable dielectric properties and leakage current behaviors as a function of film thickness and deposition temperature. The capacitance density and breakdown field of 150-nm-thick-BMN films deposited at 150 °C were approximately 325 nF/cm2 and 410 kV/cm, respectively. The BMN films showed a dielectric constant of 55, a dielectric loss of 1.6% at 100 kHz, and a leakage current density of 1×10-8 A/cm2 at an applied field of 250 kV/cm. Metal/insulator/metal (MIM) capacitors including various bismuth-based pyrochlore films are expected to be promising candidates for printed circuit board (PCB)-embedded capacitors.
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