[(C⁁N⁁N)Pt(CC)nR] (HC⁁N⁁N = 6-aryl-2,2′-bipyridine, n = 1–4, R = aryl, SiMe3) as a new class of light-emitting materials and their applications in electrophosphorescent devicesElectronic supplementary information (ESI) available: General experimental procedure, analytical and spectral characterizations, OLED fabrication and performance. See http://www.rsc.org/suppdata/cc/b1/b108793b/