Microfluidic electrogenerated chemiluminescence cells using aluminum-doped zinc oxide nanoparticles as an electron injection layer

We demonstrated highly luminescent microfluidic electrogenerated chemiluminescence (ECL) cells using aluminum-doped zinc oxide nanoparticles (AZO NPs) as an electron injection layer (EIL). The 5-μm-thick electro-microfluidic device, in which an approximately 1.6-μm-thick AZO NPs layer was embedded, was fabricated by microelectromechanical systems processes and a vacuum ultraviolet-assisted direct bonding technique. A tris(2,2′-bipyridine)ruthenium(II) solution was used as an orange-red emitter. A luminance and a half-lifetime were measured to be 161 cd/m² at 3.3 V and 30 s at 3.0 V, respectively, which were 2.5 times higher and 4.3 times longer than those of the device without EIL. We also compared the EIL performance of the AZO NPs with that of titanium dioxide NPs. Furthermore, 2-μm-thick microfluidic ECL cell with the AZO NPs layer was fabricated by the same process, and the maximum luminance increased up to 240 cd/m². We expect that the developed microfluidic device will be highly attractive for solution-based display applications.