Papers by Andrew Grimsdale
Chemical Communications, 2003
Acs Symposium Series, Sep 1, 1997
Macromolecular Chemistry and Physics, Oct 26, 2015
Nanocomposites with organic-inorganic properties represent a new fi eld of basic research and off... more Nanocomposites with organic-inorganic properties represent a new fi eld of basic research and offer prospects for many novel applications in extremely diverse fi elds, due to their remarkable emerging new properties and multifunctional nature. However, controllable manipulation of their fl uorescent properties in different phases is still challenging, which seriously limits the related applications of nanocomposites. In this work, a convenient protocol to fabricate organic-inorganic nanocomposites composed of stilbene chromophores and CdZnS/ZnS quantum dots (QDs) pairs, with controllable fl uorescent properties is presented. It is found that stable white-light emission can be achieved only in solution phase, with negligible energy transfer or reabsorption between chromophores and QDs pairs. By contrast, when the nanocomposites are deposited as blended fi lms, they cannot give rise to white-light emission, no matter what donor/acceptor volume ratios are used. However, the blended fi lms can exhibit near-unity effi ciency (94%) of Förster resonance energy transfer from QDs to chromophores. The underlying physical mechanisms are revealed through comprehensive steady-state and time-resolved spectroscopic analysis. This work suggests that the CdZnS/ZnS QDs/stilbene nanocomposites can be directly used for fl uorescence sensors and probes in biological system as well as fundamental investigation of lightharvesting, and also sheds light on developing other new materials for artifi cial photosynthesis and optoelectronics.
Chemistry of Materials, Feb 17, 2022
Physical review, Jun 15, 1996
We report fluorescence measurements on poly(p-phenylene vinylene͒, PPV, and four derivatives of t... more We report fluorescence measurements on poly(p-phenylene vinylene͒, PPV, and four derivatives of this polymer, all of which show strong luminescence and can be used as emissive materials in electroluminescent diodes. We measure the variation of the emission spectrum with excitation energy at low temperature, and find a threshold energy above which emission is independent of excitation energy and below which the emission energy tracks with the excitation energy. This information makes it possible to separate out the effects of spectral diffusion by exciton migration from other forms of excited-state relaxation. We find that PPV and two derivatives with asymmetric, branches side chains show little or no excited-state relaxation. In contrast, the other two derivatives ͑one with bromine and dodecyloxy attachments at the two and five positions on the phenylene, the other with hexyloxy attachments at these sites, and cyano groups at the vinylic carbons͒ show further relaxation by about 0.25 eV. We consider that emission in these two polymers is from an interchain excimer excited state. Supporting evidence for the cyano-PPV is seen in the differences between the dilute solution and solid-state fluorescence spectra. ͓S0163-1829͑96͒00523-1͔
Elsevier eBooks, 2013
Abstract: In this chapter the discovery, formation, effects and suppression of fluorenone defects... more Abstract: In this chapter the discovery, formation, effects and suppression of fluorenone defects in fluorene-based conjugated polymers are discussed. The discovery of how these defects are responsible for the formation of green emission from these polymers enabled methods, including improved synthesis methods and the design of new molecular and device structures, to be devised for its suppression. Comparisons are made to the behaviour of other bridged phenylene polymers which also illustrate the widespread applicability of the methods used for suppression of fluorenone defects to the optimisation of other classes of polymers.
Chemistry of Materials, Mar 15, 2019
Room-temperature phosphorescence (RTP) has a much longer lifetime than fluorescence as it involve... more Room-temperature phosphorescence (RTP) has a much longer lifetime than fluorescence as it involves triplet excitons. This extended lifetime enables the design of advanced optoelectronics and biological sensing technologies. Despite the omnipresence of triplet states, harnessing these triplet excitons remains challenging for most organic materials due to the forbidden transitions between singlet and triplet states. Here we report novel organic-inorganic hybrid perovskites based on conjugated organic cations with low-lying triplet energy levels to extract triplet excitons from the inorganic component, thereby generating RTP with long lifetime in millisecond range. Dexter type energy transfer was confirmed to occur in this type of hybrid perovskites with transfer efficiency of up to 80%. More impressively, multiplecolored phosphorescence was achieved by facile design of the system using organic cations with different triplet exciton energies. These results are expected to greatly expand the prospects of hybrid perovskites with functional organic cations for versatile display applications.
ACS applied energy materials, Jan 27, 2023
Elsevier eBooks, 2016
The efficiency of LEDs based on conjugated polymers have been enhanced so that they are now comme... more The efficiency of LEDs based on conjugated polymers have been enhanced so that they are now commercially viable. This has occurred in large part by better synthetic design of emissive materials, based on an improved understanding of reaction mechanisms and how these permit defect formation through side reactions, thus enabling their prevention by modification of synthetic route or monomer structure. The performance of polymer-based solar cells has also been improved so that they are now close to commercialization. Again this has been due to synthetic design based on an enhanced knowledge of the underlying processes affecting efficiency, enabling a better understanding of structure-property relationships. The prospects for the future of both classes of device are assessed.
Angewandte Chemie, Feb 16, 1998
ABSTRACT
Australian Journal of Chemistry, 1990
Podocarpic acid (11) has been converted into the congener (5) of confertifolin (4) through the o-... more Podocarpic acid (11) has been converted into the congener (5) of confertifolin (4) through the o-quinone (29) formed by oxidations of the catechol monoether (15) and the 13-amine (16) with Fremy's salt. Oxidation of the methyl ether (12) afforded the p-quinone (44) which was converted into the congener (6) of winterin (7). Podocarpic acid has also been converted into the congener (8) of isodrimenin (9) through the catechol derivative (37).
Wiley-VCH Verlag GmbH & Co. KGaA eBooks, Jan 20, 2017
Current Organic Chemistry, Nov 1, 2010
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Papers by Andrew Grimsdale