“…It has been proposed that the analogous, broad, highly Stokes-shied emission from ultra-small cadmium chalcogenide nanocrystals is caused by strong exciton-phonon coupling of surface-oriented states, rather than evidence of deep trap states within the optical gap. 51,52 Similarly, excitonphonon coupling has been proposed as the dominant origin of the room-temperature PL linewidth and dynamics of larger PbS QDs, 49,53,90,95 is expected to strengthen as the QD radius decreases, 54,96,97 and has been invoked to explain charge-transfer intermediates in the sensitization of triplet excited-states of larger acenes. 64,71 Naturally, any homogenous origin for the broad emission of these ultra-small PbS QDs would explain the spectral invariance that we observe for the K describing the TET quasi-equilibrium.…”