White organic light-emitting diodes (WOLEDs) have attracted more and more attention in recent years because of their potential applications on flat-panel displays, solid-state lighting, and liquid-crystal display backlighting sources. With the goal towards practical applications, it requires WOLEDs possess not only high brightness and large electroluminescent (EL) efficiency, but also excellent stability. Here, good device stability includes two aspects, these are long operation lifetime and good color stability over a wide EL range. In this review, we explored all possible factors rendering a shift in color in both single-and multiple-emitting layer WOLEDs and summarized some typical design strategies for preventing shift in color of white emission. We hope the present paper can provide valuable clues to academic researchers and industrial designers in developing highly efficient WOLEDs with extremely stable chromaticity.

The commonly used donor material poly(3-hexylthiophene) (P3HT) confines the power conversion efficiency (PCE) in P3HT-based polymer solar cells due to its relatively large bandgap of $1.9 eV and the resultant limited absorption wavelength region of less than 650 nm. In this communication, the highly efficient up-conversion (UC) material NaYF 4 :2% Er 3+ , 18% Yb 3+ , converting near-infrared radiation into green and red emissions, is introduced into a P3HT/P3HT:[6,6] phenyl C 61 butyric acid methyl ester (PC 61 BM) bulk heterojunction solar cell, referred to as a "bilayer cell", to compensate for the nonabsorbable wavelength region of P3HT. With an optimal UC doping concentration of 11.7% (weight ratio of UC to P3HT) in the P3HT matrix, the short-circuit current density and PCE for UC-doped bilayer cell are as high as 10.89 mA cm À2 and 3.62%, about 16.6% and 10.7% higher than the P3HT/ P3HT:PC 61 BM bilayer cell and 22.4% and 16.4% higher than the standard P3HT:PC 61 BM bulk heterojunction one, respectively, although the fill factor in the UC-doped bilayer cell shows a slight decrease. The research result demonstrates that both the emission and the scattering of UC nanoparticles are beneficial to the enhancement of the solar cell's electrical performances.

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Plasmon-enhanced polymer photovoltaic cells based on large aspect ratio gold nanorods and the related working mechanism

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The output of Terfenol-D is nonlinear and hysteretic under the effect of magnetic field and prestress. The nonlinear constitutive relation between magnetostriction and magnetization with magneto-stress coupling was built in consideration of the magnetostriction saturation and the prestress correlation. Then, the hysteresis behavior of Terfenol-D was modeled based on the Jiles-Atherton model. The error of magnetostriction between simulations and experimental data is less than 6%. This result indicates that the model can adequately predict the nonlinear hysteresis and magneto-stress coupling character of Terfenol-D.