Here, we consider that the upconversion of a CT singlet exciton to an LE singlet state enables emission blueshifting in binary OLPL systems, giving the mechanistic similarity of OLPL to the recombination luminescence in OSCs. We prepared a series of OLPL systems having gradient variations in ΔELUMO by selecting a series of donor and acceptor materials having similar structures but gradually varying HOMO or LUMO energy levels (Figs. ). Comprehensive characterization using steady-state, time-resolved spectroscopy, and wavelength-resolved thermoluminescence (TL) measurements enabled the analysis of complex emission processes involving charge and energy transfer, including fluorescence, thermally activated delayed fluorescence (TADF), phosphorescence, and LPL. Further, we confirmed the upconversion from CT to LE singlet state in the small ΔELE-CT systems and achieved blue and cyan OLPL. TL analysis indicates that a thermally activated trap-filling process and the small ΔELUMO can enhance trap-filling at room temperature. By adding suitable extrinsic electron traps to the system, we achieved strong LPL up to ISO 17398 class A.