Search

A tandem solar cell, composed of a MEH-PPV:PCBM bulk heterojunction front sub-cell and a CuPc/PCBM small molecule back sub-cell, is fabricated by spin-coating and vacuum evaporating methods. Measurement results show that an optimal tandem solar cell with 50 nm MEH-PPV:PCBM active layer thickness and 0.5 nm Ag inter-layer thickness can be obtained with a power conversion efficiency of 1.86%

We fabricate efficient bulk heterojunction organic photovoltaic (OPV) device based on poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV), with copper(Ⅱ) phthalocyanine (CuPc) used as a donor and -phenyl C61-butyric acid methyl ester (PCBM) serving as an acceptor. The power conversion efficiency of the MEH-PPV/PCBM OPV device with 15% CuPc (1.41%) increases by 12% compared with that of the standard MEH-PPV/PCBM device (1.26%). The efficiency improvement can be attributed to the CuPc supplemental absorption and higher mobility than MEH-PPV, leading to increased short-circuit current density.

A threshold condition different from the classical one is proposed for MOSFET with quantum effects, by means of self-consistent numerical solution of the Schrdinger's and Poisson's equations, and thus an accurate 1-D threshold-voltage model is obtained with good agreements between simulated results and measurement data. Based on this 1-D model, an accurate 2-D quantum-modified threshold-voltage model for small-scale MOSFET is developed by solving the quasi-2D Poisson's equation and taking short-channel effects and quantum-mechanical effects into consideration. The model can also be used for simulation of electrical properties and design of structural parameters for deep-submicron MOSFETs with high-k materials as gate dielectric.

An analytic model of direct tunneling current of small-scale MOSFETs in depletion and inversion is developed based on analytic surface-potential model and replacing the multi-subband with a single-subband. The simulated results are in good agreement with the results of self-consistent solution and experimental data, but take much shorter computing time than the self-consistent solution method. This indicates that the model can be used for analysis of gate-leakage properties of MOS devices with not only SiO2 but also high-k materials as gate dielectric and high-k gate dielectric stack structures, and circuit simulation of MOS devices.