Fig. 1: Intensity-dependent photoluminescence quantum efficiency of Y6.
From: Free charge photogeneration in a single component high photovoltaic efficiency organic semiconductor
a Normalised photoluminescence efficiency, as a function of excitation density, of 130 nm thick (blue dots) and 80 nm thick (orange dots) neat films of Y6 on a glass substrate. The sample was excited by 600 ps pulses of 532 nm light. The sample was measured in vacuum, and the relative photoluminescence efficiency was determined from the ratio of the 2nd harmonic scatter peak at 1064 nm to the integrated PL intensity between 850 and 1050 nm. The error bars shown represent the relative error of the change in PL at different excitation densities, rather than the total error (details in the Supplementary Information). b Simulation of intensity-dependent PLQE values showing effect of increasing (orange) or decreasing (blue) radiative bimolecular recombination (from prompt free charge fraction, calculated using the model detailed in the text and SI. c Graphic representation of exciton-free charge equilibrium in Y6.
