Exciton Charge Separation — 1D Space–Time Kymograph

This is a genuinely 2D-native counterpart to the 3D donor–acceptor particle scene: since only the depth coordinate decides whether a photogenerated exciton reaches the interface, the whole random walk collapses exactly onto one spatial axis, plotted here as a scrolling position-vs-time kymograph — a distinct representation used across physics and biology to read a diffusing population's whole history at a glance rather than a moment of it. The left panel scrolls a colour-coded density trace (excitons, electrons, holes) built from an independent 1D Monte Carlo random walk using the same D = L_D²/τ diffusion law; the right panel plots the analytic Onsager–Braun dissociation-probability curve P_diss(F) alongside a live marker for the Monte Carlo dissociation fraction actually measured at the interface, so the same physics is checked two ways at once as you sweep field, temperature and charge-transfer separation.