Fabrication of Bragg Mirrors by Multilayer Inkjet Printing. Issue 33 (13th July 2022) - Zhang, Qiaoshuang
Abstract: Bragg mirrors are widely applied in optical and photonic devices due to their capability of light management. However, the fabrication of Bragg mirrors is mainly accomplished by physical and chemical vapor deposition processes, which are costly and do not allow for lateral patterning. Here, the fabrication of Bragg mirrors by fully inkjet printing is reported. The photonic bandgap of Bragg mirrors is tailored by adjusting the number of bilayers in the stack and the layer thickness via simply varying printing parameters. An ultrahigh reflectance of 99% is achieved with the devices consisting of ten bilayers only, and the central wavelength of Bragg mirrors is tuned from visible into near‐infrared wavelength range. Inkjet printing allows for fabricating Bragg mirrors on various substrates (e.g., glass and foils), in different sizes and variable lateral patterns. The printed Bragg mirrors not only exhibit a high reflection at designed wavelengths but also show an outstanding homogeneity in color over a large area. The approach thus enables additive manufacturing for various applications ranging from microscale photonic elements to enhanced functionality and aesthetics in large‐area displays and solar technologies. Abstract : Fully inkjet‐printed Bragg mirrors are fabricated by alternately depositing poly(methyl methacrylate) (PMMA) and titanium dioxide (TiO2 ) composite thin‐film layers. The Bragg mirrors are tunable in color/spectrum by simply adjusting the printing parameters. With precise control of the layer thickness and uniformity, the reflectance of the printed Bragg mirrors reaches 99% with ten bilayers only.