Fig. 3: The effect of the guest composition on non-radiative recombination losses.

a–c, EQE_ELas a function of the composition: in the practically relevant range (usually <80% PC₇₁BM), the EQE_ELvalues are almost constant (a), continuously decreasing (b) and rising (c). d–f, EL spectra of three representative ternary systems: upon adding PC₇₁BM, the EL spectra of the host binary blend remain almost identical (d, PBDB-T: Y1: PC₇₁BM), gradually show the guest binary EL (e, PM6: ITCC: PC₇₁BM) or blue shift (f, PBDB-T: IEICO-4F: PC₇₁BM); the dashed arrows on the EL spectra in e,f are guides for the eyes to indicate the gradual change of the EL spectra; the insets in d–f depict the relative energy levels (exact values in Supplementary Table 7) and the relatively high luminescence quantum yields of the host CT states (indicated by the thicker arrows) and the relatively low luminescence quantum yields of the guest CT states (indicated by the thinner arrows). g, Illustration of the energetic levels in the multi-state simulation studying the thermal population effects on the EQE_EL versus compositions by changing the energy of the guest CT state \(({E}_{{\mathrm{CT}}_{\mathrm{G}}})\) from 1.60 eV to 1.30 eV (indicated by the dashed arrow). h, Simulation results of the thermal population effects on the EQE_EL versus compositions by changing the \({E}_{{\mathrm{CT}}_{\mathrm{G}}}\) from 1.60 eV to 1.30 eV (indicated by the dashed arrow) and fixing the energy levels of the other states. i, Simulation results of the increased photoluminescence quantum yields (PLQYs) (related to the LE_H states) affecting the EQE_EL versus compositions (plotted with blue symbols); to make a direct comparison, the experimentally measured EQE_EL values in the PBDB-T: IEICO-4F: PC₇₁BM are also plotted in i. In all figures, the lines connecting the points are the guides for eyes.

Source data