Oleic acid (OA) modified zinc-blende cadmium selenium nanocrystals (NCs) with different diameters, 3-5 nm, have been prepared. We find that the morphology and fluorescent properties of the samples are related to the preparation conditions such as the chain-length and concentration of the cadmium precursor as well as the concentration of OA. The hybrid solar cells based on the obtained spherical CdSe NCs as an acceptor and Poly(2-methoxy-5-(2'-ethylhexoxy)-p-phenylenevinylene) (MEH-PPV) as a donor show an energy conversion efficiency (ECE) as high as 0.85%, three times higher than that reported before for spherical CdSe NCs/conjugated polymer hybrid solar cells. When poly(3-hexylthiophene) (P3HT) is used as the donor phase instead of MEH-PPV, the energy conversion efficiency increases up to 1.08%. The solar cell based on CdSe NCs/conjugated polymer has the potential to open up new production technologies for hybrid solar cells based on semiconductor NCs.

Multiarmed CdS nanorods have been used as the electron acceptors to fabricate efficient hybrid solar cells. It was demonstrated that when pyridine was used as a solvent for spin coating an active layer consisting of MEH-PPV/CdS blend instead of chlorobenzene, short-circuit current of the device can typically be increased by six times. The FTIR transmission spectrum shows that pyridine replaces the surfactant (HDA) molecules attached to the nanocrystals' surface after posttreatment of CdS nanorods by refluxing in pyridine. Transmission electron microscopy, atomic force microscopy, current-voltage characteristics, photocurrent action spectra measurements, and photoluminescence quenching were used to characterize MEH-PPV/CdS blend spin-coated from pyridine solution. Thermal treatment of the blend films can further enhance the short-circuit current in the device. Best device performance was achieved with a power conversion efficiency of 1.17% under AM1.5 illumination (100 mW cm -2 ), significantly higher than that reported so far for MEH-PPV/CdS hybrid devices.

SiC MOSFETs (silicon carbide metal-oxide semiconductor field-effect transistors) are replacing Si insulated gate bipolar transistors in many power conversion applications due to their superior performance. However, ruggedness and reliability of SiC MOSFETs are still big concern for their widespread applications in the market, especially in safety-critical applications. The objective of this study is to provide a comprehensive picture on the ruggedness and reliability of commercial SiC MOSFETs, discover their failure or degradation mechanism, and propose some possible mitigation methods through both literature survey and in-depth analysis. The ruggedness of SiC MOSFETs discussed here includes short-circuit (SC) ruggedness, avalanche ruggedness, and their failure mechanism. The reliability issues include gate oxide reliability, degradation under high-temperature bias stress, repetitive SC stress, avalanche stress, power cycling stress, body diode's surge current stress, and their degradation mechanism. Furthermore, this study discusses methods and solutions to improve their ruggedness and reliability.

No abstract

No abstract

No abstract

No abstract

No abstract