(Figure ). The emission of the resulting compounds is tuned based on the choice of donor, with emission maxima ranging from red to NIR, peaking at λPL of 643, 743, and 722 nm in toluene solution for DMACPyBP, PXZPyBP and DPACzPyBP, respectively. DMACPyBP and DPACzPyBP exhibit small ΔEST values of 0.02 and 0.07 eV, while PXZPyBP, with the weakest donor PXZ, shows the largest ΔEST of 0.10 eV in 1 wt% doped CBP films. The corresponding ΦPL and kRISC values are 62.3, 26.6, and 21.2%, and 0.5 × 10 5 , 0.3 × 10 5 , and 0.04 × 10 5 s -1 for DMACPyBP, DPACzPyBP, and PXZPyBP, respectively. Figure summarises the variations in the key photophysical properties of these three emitters.