Radiative characteristics of nanopatch antennas based on plasmonic nanoparticles of various geometry and tris(2,2’-bipyridine) ruthenium(II) hexafluorophosphate

Abstract

Effective interaction of light with quantum emitters is important for the development of efficient high-frequency nanophotonic devices. One of the most attractive ways of solving this problem is the employment of nanopatch antennas (NPAs) with various efficient photon emitters. In the present study, we investigated the properties of the NPAs with different geometries involving a [Ru(bpy)3]2+ complex (tris(2,2’-bipyridine) ruthenium(II) hexafluorophosphate) which was taken as a highly stable emitter. An increase in the radiation power of the metalorganic system was experimentally obtained. In particular, an increase in the photoluminescence intensity of the emitter was observed, and a significant reduction (down to 7 ns) in the lifetime of the excited states in the Ru-complex (with ‘free’ lifetime of about 850 ns) was demonstrated for an inhomogeneous ‘aluminum-silver nanoparticle’ system incorporating the Ru-complex. The increase in the spontaneous emission rate of [Ru(bpy)3]2+ was attributed to the Purcell effect. The averaged values of the Purcell factors obtained for the emitter in the resonator with pentagonal and hexagonal silver nanoparticles were 100 and 120, respectively. It was shown that in an NPA with single vertically oriented emitters, the maximum values of the Purcell factors can be as high as 103. Also, radiation patterns were simulated showing that the radiation maximum is observed at an angle of about 50° to the surface of the nanoantenna. Luminescence enhancement factors for the studied types of NPAs were obtained both experimentally and theoretically.