Browsing by Subject "Fluorescence resonance energy transfer"
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Item Open Access Conjugated polymer nanoparticles(2010) Tuncel, D.; Demir, Hilmi VolkanConjugated polymer nanoparticles are highly versatile nano-structured materials that can potentially find applications in various areas such as optoelectronics, photonics, bio-imaging, bio-sensing and nanomedicine. Their straightforward synthesis in desired sizes and properties, biocompatibility and non-toxicity make these materials highly attractive for the aforementioned applications. This feature article reviews the recent developments in the synthesis, characterization, properties and application of these exciting nanostructured materials.Item Open Access Mutual energy transfer in a binary colloidal quantum well complex(American Chemical Society, 2019) Yu, J.; Sharma, Manoj; Delikanlı, Savaş; Birowosuto, M. D.; Demir, Hilmi Volkan; Dang, C.Förster resonance energy transfer (FRET) is a fundamental process that is key to optical biosensing, photosynthetic light harvesting, and down-converted light emission. However, in total, conventional FRET in a donor–acceptor pair is essentially unidirectional, which impedes practical application of FRET-based technologies. Here, we propose a mutual FRET scheme that is uniquely bidirectional in a binary colloidal quantum well (CQW) complex enabled by utilizing the d orbital electrons in a dopant–host CQW system. Steady-state emission intensity, time-resolved, and photoluminescence excitation spectroscopies have demonstrated that two distinct CQWs play the role of donor and acceptor simultaneously in this complex consisting of 3 monolayer (ML) copper-doped CQWs and 4 ML undoped CQWs. Band-edge excitons in 3 ML CQWs effectively transfer the excitation to excitons in 4 ML CQWs, whose energy is also harvested backward by the dopants in 3 ML CQWs. This binary CQW complex, which offers a unique mutual energy-transfer mechanism, may unlock revolutionary FRET-based technologies.Item Open Access Quantum dot integrated LEDs using photonic and excitonic color conversion(Elsevier, 2011-11-23) Demir, Hilmi Volkan; Nizamoglu, S.; Erdem, T.; Mutlugun, E.; Gaponik N.; Eychmüller A.This review summarizes advantages, recent progress and challenges related to the quickly evolving research field of colloidal quantum dot integrated LEDs based on color conversion. We start with presenting a short general introduction to the field of solid state lighting and color conversion phenomena, which are essential for defining the requirements for high-quality general lighting. Subsequently we continue with a brief description of the synthesis of nanocrystal quantum dots and their optical properties together with the advantages of utilizing them in LEDs as color convertors. Following this basic background, we review the recent efforts on quantum dot integrated color-conversion LEDs, Förster resonance energy transfer (FRET) converted LEDs and FRET-enhanced LEDs. Finally, we conclude with a future outlook on semiconductor lighting and quantum dot integrated LEDs.Item Open Access Ultraefficient förster-type nonradiative energy transfer enabled by the complex dielectric medium with tuned permittivity(American Chemical Society, 2021-06-10) Hernandez-Martinez, P. L.; Yücel, A. C.; Demir, Hilmi VolkanFörster-type nonradiative energy transfer (FRET) is one of the primary near-field phenomena and is a useful, fundamental mechanism allowing us to control the excitation energy flow. Using carefully chosen pairs of quantum emitters/absorbers (donors/acceptors), FRET has proved to be essential in a variety of light-generating and -harvesting systems. However, FRET takes place only in a limited spatial range, and its efficiency suffers from an adversely rapidly decreasing profile over the increasing distance between the donor and acceptor. To foster FRET, reaching ultimate levels of efficiency and extending its range, we systematically studied the FRET mechanism by tuning the background medium’s permittivity. The FRET rates of donor–acceptor pairs consisting of a point-like, quasi-0-dimensional quantum dot and quasi-2-dimensional quantum well nanostructures are analytically derived to characterize the change of FRET rates with respect to the medium’s permittivity. The analysis reveals that the FRET rate becomes singular when the permittivity approaches zero and there is a fixed value for the point-like and all other nanostructures, respectively. By setting the medium’s relative permittivity to realistic values near the singular point, which can be realized by a digital metamaterial approach, ultrahigh FRET rates and thereby ultraefficient FRET-based systems are achievable.