where μ and m refer to the electric transition dipole moment and magnetic transition dipole moment vectors between the emissive excited state and the ground state, respectively, and q is the angle between μ and m. For closed shell organic small molecules, including MR-TADF emitters, |μ| is roughly 300 times larger than |m|, which results in very small gPL values, typically less than 10 -2 . Given the large electric transition dipole moment, equation 3 can be simplified to equation 4: