Fig. 3: Kinetic model of charge generation in Y6 with transient absorption, PLQE and predicted steady-state free charge fractions.

a Jablonski diagram highlighting key excited-state pathways – rapid initial interconversion (solid red arrows), charge recombination (solid orange arrows), non-radiative (red dashed arrows), and radiative rates (green arrows). b Normalised transient absorption kinetics of excitons (blue circles) and (c) charge states (orange circles) at different excitation densities, fitted with a global fit to the basic kinetic model described in the text and SI (solid blue and orange lines). d Internal (blue crosses) and external (red crosses) PLQE values of Y6 as a function of excitation density, with corresponding simulated values from fits to the transient absorption and intensity dependent PLQE. Internal PLQE is calculated from external PLQE as per Richter et al.⁴¹. The solid blue line is the simulated PLQE from the basic model, the dashed blue line shows the PLQE calculated when TTA is included, and the dotted blue line shows the estimated PLQE from an explicit treatment of hole traps (but no TTA). e Steady-state free charge fraction as a function of total excitation density calculated from the rate constants gathered from the basic kinetic model (red line), and from an estimate from the Saha equation (blue line). The Saha equation is calculated based on an excitonic binding energy of 270 meV, corresponding to an exciton effective mass of ~0.5 m_e.