Sub-10-fs observation of bound exciton formation in organic optoelectronic devices comes out in Nature Communications. I participated in the ultrafast Pump – Probe, Pump-Push-Photocurrent and Pump-Push-Photoluminescence setup development and alignment, the fastest spectroscopic setup I ever worked with. (in absolute values – THz setups allow for Single oscillation pulses and time resolutions compared with wavelength/c).
We find that excitons created by near-absorption-edge photons are intrinsically bound states, or become such within 10 fs after excitation. Meanwhile, excitons with a modest >0.3 eV excess energy can dissociate spontaneously within 50 fs before acquiring bound character.