Publications
5 results found
Maimaris M, Pettipher AJ, Azzouzi M, et al., 2022, Sub-10-fs observation of bound exciton formation in organic optoelectronic devices, Nature Communications, Vol: 13, ISSN: 2041-1723
Fundamental mechanisms underlying exciton formation in organic semiconductors are complex and elusive as it occurs on ultrashort sub-100-fs timescales. Some fundamental aspects of this process, such as the evolution of exciton binding energy, have not been resolved in time experimentally. Here, we apply a combination of sub-10-fs Pump-Push-Photocurrent, Pump-Push-Photoluminescence, and Pump-Probe spectroscopies to polyfluorene devices to track the ultrafast formation of excitons. While Pump-Probe is sensitive to the total concentration of excited states, Pump-Push-Photocurrent and Pump-Push-Photoluminescence are sensitive to bound states only, providing access to exciton binding dynamics. 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. These conclusions are supported by excited-state molecular dynamics simulations and a global kinetic model which quantitatively reproduce experimental data.
Maimaris M, Pettipher AJ, Azzouzi M, et al., 2022, Sub-10fs Photocurrent and Photoluminescence Action Spectroscopies of Organic Optoelectronic Devices Reveals Ultrafast Formation of Bound Excitonic States
We apply ultrafast pump-push-photocurrent and pump-push-photoluminescence spectroscopies to polyfluorene organic diode to track in time the bound exciton formation. ‘Cold’-excitons become bound within 10-fs while ‘hot’-excitons can dissociate spontaneously within 50-fs before acquiring bound character.
Crespo H, Witting T, Canhota M, et al., 2020, In-situ temporal measurement of ultrashort laser pulses at full power during high-intensity laser-matter interactions, Optica, Vol: 7, Pages: 995-1002, ISSN: 2334-2536
In laser-matter interaction experiments it is of paramount importance to be able tocharacterise the laser pulse on target (in-situ) and at full power. This allows pulse optimisationand meaningful comparison with theory, and can shed fundamental new light on pulse distortionsoccurring in or on the target. Here we introduce and demonstrate a new technique based ondispersion scan using the concurrent third harmonic emission from the target that permits the full(amplitude and phase), in-situ, in-parallel characterisation of ultrashort laser pulses in a gas orsolid target over a very wide intensity range that encompasses the1013−1015W cm−2regime ofhigh harmonic generation and other important strong field phenomena, with possible extensionto relativistic intensities also presently inaccessible to other diagnostics.
Crespo H, Canhota M, Witting T, et al., 2019, Direct measurement of intense sub-4-fs pulses in a gas target by 3rd-harmonic dispersion-scan, 21st International Conference on Ultrafast Phenomena (UP), Publisher: E D P SCIENCES, ISSN: 2100-014X
Fabris D, Holgado W, Silva F, et al., 2015, Single-shot implementation of dispersion-scan for the characterization of ultrashort laser pulses, OPTICS EXPRESS, Vol: 23, Pages: 32803-32808, ISSN: 1094-4087
- Author Web Link
- Open Access Link
- Cite
- Citations: 27
This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.