The present invention relates to light emitting materials comprising novel ortho-metalated transition metal complexes C^N2MN^N comprising two orthometalated ligands and a neutral bidentate bipyridine ligand. The method includes forming an active area of the test macro having a first and second gate region and forming a first and second sourcedrain regions in the active area. An actuator is movably connected with the housing and arranged to rotate the bottle within the housing. The common-base transistor may have a base configured to receive a reference voltage.