Alternating-current electroluminescence from an organic heterojunction sandwiched between two amorphous SiO2 layers

We report alternating-current electroluminescence (ACEL) from an organic heterojunction sandwiched between two amorphous ${\mathrm{SiO}}_2\left(\alpha \text{-}{\mathrm{SiO}}_2\right)$ layers, i.e., $\mathrm{ITO}\backslash \alpha \text{-}{\mathrm{SiO}}_2\backslash \mathrm{poly}\left[2\text{-methoxy-}5\text{-}\left(2^{\prime }\text{-ethylhexyloxy}\right)\text{-}p\text{-phenylene vinylene}\right]\left(\mathrm{MEH}\text{-}\mathrm{PPV}\right)\backslash \mathrm{Al}{q}_3\backslash \alpha \text{-}{\mathrm{SiO}}_2\backslash \mathrm{Al}$ . Besides the exciton radiation from $\mathrm{Al}{q}_3$ (peak at 520 nm) and MEH-PPV (peak at 587 nm), an additional broad blue emission around 410 nm is observed in its ACEL spectrum. By studying the ACEL and brightness wave form of the device, we found both hot-electron-impact excitation and injection carriers recombination are combined in its emission mechanism for this hybrid organic-inorganic structure, and the origin of the broad blue emission around 410 nm is discussed.