Devices and techniques are disclosed herein which include a first LED device layer, a second LED device layer, and an adhesive bondline disposed between the first LED device layer and the second LED device layer. The adhesive bondline includes a bondline thickness, a plurality of spacers disposed within the adhesive bondline, and a silicone matrix. The plurality of spacers may have a diameter or a shortest axis between 0.5 and 10 micrometers and the coefficient of variation is 10% or less. The plurality of spacers may be include SiO2, alumina, soda lime glass, may be inorganic, or polymeric.