This is a 2D diagram, not a flattened 3D scene: instead of watching an arbitrary spatial cloud of glowing spheres, the top panel is a Jablonski energy-level diagram — the standard 2D notation photophysicists use, where the vertical axis is energy state (excited S1 above, ground S0 below), not spatial position. The bottom panel is a live time-resolved photon decay curve, exactly what a real TCSPC (time-correlated single-photon counting) instrument records in the lab to measure lifetime and quantum yield.
Each dot still runs its own stochastic two-level exciton clock — a radiative pathway (rate kr, emits a photon) competing with a non-radiative pathway (rate knr, surface traps + phonons):
Φ = k_r / (k_r + k_nr)
τ = 1 / (k_r + k_nr)
k_nr = D_trap · k_trap,max · S_shell + A · exp(−E_a / k_B T)
Every radiative decay drops one photon into the decay-curve panel at its own waiting time since excitation. Because that waiting time is drawn from an Exponential(k_r+k_nr) distribution, the histogram of thousands of these events reconstructs the same exponential survival curve N(t) = N₀·exp(−t/τ) that a real TRPL instrument plots on a semi-log axis — the dashed reference line is that theoretical curve, and a straight line on the semi-log plot is the classic lab confirmation of single-exponential decay.
- Surface trap density — unpassivated dangling bonds competing with radiative recombination.
- Temperature — raises the thermally activated (Arrhenius) non-radiative rate.
- ZnS Shell Passivation — buries surface traps, suppressing that term to ~5%.
- Pump rate — how often ground-state dots are re-excited; changes brightness/photon-arrival rate but not Φ or the decay-curve slope, since both depend only on the rate ratio and rate sum.