Bias-Polarity Dependent Ultraviolet/Visible Switchable Light-Emitting Devices

Abstract

By taking semiconductors with different band-gap energies as the active layers and controlling the electron-hole recombination region through the electric field, bias-polarity dependent ultraviolet/visible switchable light-emitting devices have been realized in Au/MgO/Mg0.49Zn0.51O/MgxZn1-xO/n-ZnO structures, of which the emission bands can be switched from the ultraviolet region to the orange region by changing the polarity of the applied bias. The results reported here may provide a feasible idea to multicolor-switchable light-emitting devices.

Improved Electrical Transport and Electroluminescence Properties of p-ZnO/n-Si Heterojunction via Introduction of Patterned SiO2 Intermediate Layer

“…As shown in Figure d, the expected band alignments at zero (blue solid line) and forward bias (pink dashed line) were drawn according to the Anderson model assuming the continuity of vacuum levels and there are no imperfections at the heterointerface, and the electrical parameters such as electron affinity (χ) and band gap ( E g ) of two semiconductors are known from the literature. In the present case, values of χ (χ ZnO = 4.35 eV, χ Si = 4.05 eV) and E g ( E g,ZnO = 3.37 eV, E g,Si = 1.12 eV) were taken, , and a type II staggered configuration is formed. Theoretically, the combination of electrons and holes proceeding on the Si side is more favorable than that on ZnO side by inspection of the band diagrams.…”

Epitaxial growth of vertically aligned ZnO nanowires for bidirectional direct-current driven light-emitting diodes applications

“…Therefore, how the non-equilibrium carriers were injected into the ZnO films was the key to reveal the origin of the EL performance. 38 Besides, the generation of electron-hole pairs though the impact ionization process cannot be excluded although the lifetime of the generated carriers was considerably smaller and a sufficient high electrical field was also indispensable, [39][40][41] as schematically illustrated in Fig. Herein, the electron generation mechanisms had two pathways, as follows.…”

“…S2a †), where these generated This journal is © The Royal Society of Chemistry 2015 holes recombined with free electrons and produced NBE UV emission. 38 Besides, the generation of electron-hole pairs though the impact ionization process cannot be excluded although the lifetime of the generated carriers was considerably smaller and a sufficient high electrical field was also indispensable, [39][40][41] as schematically illustrated in Fig. S1c.…”

Solution-Grown ZnO Films toward Transparent and Smart Dual-Color Light-Emitting Diode

“…However, the voltage-driven spectrum shift is accompanied by dramatic variation in device brightness, , which limits its applications. Recently, bias-polarity-controlled color switching has been demonstrated in both organic and inorganic LEDs with well-designed interfaces, , and it appears to be an appealing strategy to switch the lighting color of an individual LED without influencing the brightness. Extending such a concept to other LEDs and understanding the lighting mechanism will have significant impact on miniaturized optoelectronic devices.…”