Seth Coe-sullivan | Massachusetts Institute of Technology (MIT) (original) (raw)
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Papers by Seth Coe-sullivan
Chemical Physics Letters, 2006
We demonstrate exciton energy transfer from a thin film of phosphorescent dye fac tris(2-phenylpy... more We demonstrate exciton energy transfer from a thin film of phosphorescent dye fac tris(2-phenylpyridine) iridium (Ir(ppy) 3 ) to a monolayer of colloidal CdSe/ZnS core/shell quantum dots (QDs). The energy transfer is manifested in time-resolved photoluminescence (PL) measurements as elongation of the QD PL time constant from 40 to 400 ns, and a concomitant 55% increase of time-integrated QD PL intensity. The observed PL dynamics are shown to be dominated by exciton diffusion within the Ir(ppy) 3 film to the QD layer.
Over the past several years the optical and electronic properties of colloidaly synthesized nanoc... more Over the past several years the optical and electronic properties of colloidaly synthesized nanocrystals, or quantum dots (QDs), of CdSe have been extensively studied, with the aim of using QD films in solid-state opto-electronic devices. Efficient exciton generation in CdSe QDs suggests use of nanocrystal composite films in photovoltaic cells, while high luminescence quantum yields and tunability of QD emission
Light-Emitting Diodes: Research, Manufacturing, and Applications IX, 2005
Creation of patterned, efficient, and saturated color hybrid organic/inorganic quantum dot light ... more Creation of patterned, efficient, and saturated color hybrid organic/inorganic quantum dot light emitting devices (QD-LEDs) is dependent on development of integrated fabrication and patterning methods for the QD layer. We show that micro-contact printing can be applied to QD deposition, generating micron-scale pattern definition, needed in pixilateddisplay applications. We demonstrate saturated color QD-LEDs with external quantum efficiencies in excess of 1%. Combining this technique with the use of wide optical band gap host materials, and a new synthetic route for the creation of blue emitting (CdS)ZnS nanocrystals, it is now possible to fabricate QD-LEDs with saturated color emission in the red, green and blue regions of the spectrum.
Optics Express, 2014
We demonstrate surface emitting distributed feedback (DFB) lasers across the red, green, and blue... more We demonstrate surface emitting distributed feedback (DFB) lasers across the red, green, and blue from densely packed colloidal quantum dot (CQD) films. The solid CQD films were deposited on periodic grating patterns to enable 2nd-order DFB lasing action at mere 120, 280, and 330 μJ/cm 2 of optical pumping energy densities for red, green, and blue DFB lasers, respectively. The lasers operated in single mode operation with less than 1 nm of full-width-half-maximum. We measured far-field patterns showing high degree of spatial beam coherence. Specifically, by taking advantage of single exciton optical gain regime from our engineered CQDs, we can significantly suppress the Auger recombination to reduce lasing threshold and achieve quasi-steady state, optically pumped operation.
IEEE Photonics Conference 2012, 2012
Epitaxial-like colloidal quantum dot films are demonstrated as potential single material system f... more Epitaxial-like colloidal quantum dot films are demonstrated as potential single material system for red, green, and blue lasing. These prospects derive in part from the access to single exciton gain in the optically dense films.
CLEO:2011 - Laser Applications to Photonic Applications, 2011
2. Experiments and Results Dense, closely packed CdSe/ZnCdS core/shell QD thin films were created... more 2. Experiments and Results Dense, closely packed CdSe/ZnCdS core/shell QD thin films were created on glass substrates by spinning very high concentration QD solution (up to 123mg/ml in starting materials) in toluene or chloroform solvent. Time resolve photoluminescence of ...
CLEO:2011 - Laser Applications to Photonic Applications, 2011
Gallium nitride based quantum well blue-green LEDs play a crucial role as the 'backbone'... more Gallium nitride based quantum well blue-green LEDs play a crucial role as the 'backbone' in current solid state lighting (SSL) efforts. One key element in high efficiency SSL continues to be the development of luminescent materials. Colloidal CdSe-based quantum dots (QDs) ...
CLEO: 2013, 2013
ABSTRACT We have reached the long-sought single exciton gain regime in dense colloidal II-VI semi... more ABSTRACT We have reached the long-sought single exciton gain regime in dense colloidal II-VI semiconductor quantum dot films. Transient spectroscopy details their exciton dynamics, informing further development of single material based lasers across the visible.
ABSTRACT With DOE Award No. DE-EE00000628, QD Vision developed and demonstrated a cost-competitiv... more ABSTRACT With DOE Award No. DE-EE00000628, QD Vision developed and demonstrated a cost-competitive solution for increasing the light extraction efficiency of OLEDs with efficient and stable color rendering index (CRI) for solid state lighting (SSL). Solution processable quantum dot (QD) films were integrated into OLED ITO-glass substrates to generate tunable white emission from blue emitting OLED) devices as well as outcouple light from the ITO film. This QD light-enhancement substrate (QD-LED) technology demonstrated a 60% increase in OLED forward light out-coupling, a value which increases to 76% when considering total increase in multi-directional light output. The objective for the first year was an 80% increase in light output. This project seeks to develop and demonstrate a cost-competitive solution for realizing increased extraction efficiency organic light emitting devices (OLEDs) with efficient and stable color rendering index (CRI) for SSL. Solution processible quantum dot (QD) films will be utilized to generate tunable white emission from blue emitting phosphorescent OLED (Ph-OLED) devices.
Nano Letters, 2008
We demonstrate a solvent-free contact printing process for deposition of patterned and unpatterne... more We demonstrate a solvent-free contact printing process for deposition of patterned and unpatterned colloidal quantum dot (QD) thin films as the electroluminescent layers within hybrid organic-QD light-emitting devices (QD-LEDs). Our method benefits from the simplicity, low cost, and high throughput of solution-processing methods, while eliminating exposure of device structures to solvents. Because the charge transport layers in hybrid organic/inorganic QD-LEDs consist of solvent-sensitive organic thin films, the ability to avoid solvent exposure during device growth, as presented in this study, provides a new flexibility in choosing organic materials for improved device performance. In addition, our method allows us to fabricate both monochrome and red-green-blue patterned electroluminescent structures with 25 µm critical dimension, corresponding to 1000 ppi (pixels-per-inch) print resolution.
Sid Symposium Digest of Technical Papers, 2007
Chemical Physics Letters, 2006
We demonstrate exciton energy transfer from a thin film of phosphorescent dye fac tris(2-phenylpy... more We demonstrate exciton energy transfer from a thin film of phosphorescent dye fac tris(2-phenylpyridine) iridium (Ir(ppy) 3 ) to a monolayer of colloidal CdSe/ZnS core/shell quantum dots (QDs). The energy transfer is manifested in time-resolved photoluminescence (PL) measurements as elongation of the QD PL time constant from 40 to 400 ns, and a concomitant 55% increase of time-integrated QD PL intensity. The observed PL dynamics are shown to be dominated by exciton diffusion within the Ir(ppy) 3 film to the QD layer.
Advanced Functional Materials, 2005
Angewandte Chemie International Edition, 2006
Semiconductor nanocrystals (NCs) or quantum dots (QDs) show great promise for use in QD-LED (quan... more Semiconductor nanocrystals (NCs) or quantum dots (QDs) show great promise for use in QD-LED (quantum dot lightemitting device) displays, owing to their unique optical properties and the continual development of new core and core-shell structures to meet specific color needs. This in combination with the recent development of more efficient and saturated QD-LEDs as well as new QD-LED fabrication techniques, suggests that QD-LEDs have the potential to become an alternative flat-panel display technology. The ideal red, green, and blue emission spectrum of an LED for a display application should have a narrow bandwidth and a wavelength such that its color coordinates on the Commission Internationale de lEclairage (CIE) chromaticity diagram lie outside the current National Television System Committee (NTSC) standard color triangle (see ). For a Gaussian emission spectrum with a full width at half maximum (FWHM) of 30 nm and a maximized perceived power, the optimal peak wavelength for display applications is l = 610-620 nm for red, l = 525-530 nm for green, and l = 460-470 nm for blue. For the red pixels, wavelengths longer than l = 620 nm become difficult for the human eye to perceive, while those shorter than l = 610 nm have coordinates that lie inside the standard NTSC color triangle. Optimization of wavelength for the blue pixels follows the same arguments as for the red pixel, but at the other extreme of the visible spectrum. For green pixels, l = 525-530 nm provides a color triangle with the largest area on the CIE chromaticity diagram (and therefore the largest number of colors accessible by a display). Wavelengths longer than l = 530 nm make some of the blue/green area of the triangle inaccessible. Wavelengths shorter than l = 525 nm compromise the yellow display emissions.
Chemical Physics Letters, 2006
We demonstrate exciton energy transfer from a thin film of phosphorescent dye fac tris(2-phenylpy... more We demonstrate exciton energy transfer from a thin film of phosphorescent dye fac tris(2-phenylpyridine) iridium (Ir(ppy) 3 ) to a monolayer of colloidal CdSe/ZnS core/shell quantum dots (QDs). The energy transfer is manifested in time-resolved photoluminescence (PL) measurements as elongation of the QD PL time constant from 40 to 400 ns, and a concomitant 55% increase of time-integrated QD PL intensity. The observed PL dynamics are shown to be dominated by exciton diffusion within the Ir(ppy) 3 film to the QD layer.
Over the past several years the optical and electronic properties of colloidaly synthesized nanoc... more Over the past several years the optical and electronic properties of colloidaly synthesized nanocrystals, or quantum dots (QDs), of CdSe have been extensively studied, with the aim of using QD films in solid-state opto-electronic devices. Efficient exciton generation in CdSe QDs suggests use of nanocrystal composite films in photovoltaic cells, while high luminescence quantum yields and tunability of QD emission
Light-Emitting Diodes: Research, Manufacturing, and Applications IX, 2005
Creation of patterned, efficient, and saturated color hybrid organic/inorganic quantum dot light ... more Creation of patterned, efficient, and saturated color hybrid organic/inorganic quantum dot light emitting devices (QD-LEDs) is dependent on development of integrated fabrication and patterning methods for the QD layer. We show that micro-contact printing can be applied to QD deposition, generating micron-scale pattern definition, needed in pixilateddisplay applications. We demonstrate saturated color QD-LEDs with external quantum efficiencies in excess of 1%. Combining this technique with the use of wide optical band gap host materials, and a new synthetic route for the creation of blue emitting (CdS)ZnS nanocrystals, it is now possible to fabricate QD-LEDs with saturated color emission in the red, green and blue regions of the spectrum.
Optics Express, 2014
We demonstrate surface emitting distributed feedback (DFB) lasers across the red, green, and blue... more We demonstrate surface emitting distributed feedback (DFB) lasers across the red, green, and blue from densely packed colloidal quantum dot (CQD) films. The solid CQD films were deposited on periodic grating patterns to enable 2nd-order DFB lasing action at mere 120, 280, and 330 μJ/cm 2 of optical pumping energy densities for red, green, and blue DFB lasers, respectively. The lasers operated in single mode operation with less than 1 nm of full-width-half-maximum. We measured far-field patterns showing high degree of spatial beam coherence. Specifically, by taking advantage of single exciton optical gain regime from our engineered CQDs, we can significantly suppress the Auger recombination to reduce lasing threshold and achieve quasi-steady state, optically pumped operation.
IEEE Photonics Conference 2012, 2012
Epitaxial-like colloidal quantum dot films are demonstrated as potential single material system f... more Epitaxial-like colloidal quantum dot films are demonstrated as potential single material system for red, green, and blue lasing. These prospects derive in part from the access to single exciton gain in the optically dense films.
CLEO:2011 - Laser Applications to Photonic Applications, 2011
2. Experiments and Results Dense, closely packed CdSe/ZnCdS core/shell QD thin films were created... more 2. Experiments and Results Dense, closely packed CdSe/ZnCdS core/shell QD thin films were created on glass substrates by spinning very high concentration QD solution (up to 123mg/ml in starting materials) in toluene or chloroform solvent. Time resolve photoluminescence of ...
CLEO:2011 - Laser Applications to Photonic Applications, 2011
Gallium nitride based quantum well blue-green LEDs play a crucial role as the 'backbone'... more Gallium nitride based quantum well blue-green LEDs play a crucial role as the 'backbone' in current solid state lighting (SSL) efforts. One key element in high efficiency SSL continues to be the development of luminescent materials. Colloidal CdSe-based quantum dots (QDs) ...
CLEO: 2013, 2013
ABSTRACT We have reached the long-sought single exciton gain regime in dense colloidal II-VI semi... more ABSTRACT We have reached the long-sought single exciton gain regime in dense colloidal II-VI semiconductor quantum dot films. Transient spectroscopy details their exciton dynamics, informing further development of single material based lasers across the visible.
ABSTRACT With DOE Award No. DE-EE00000628, QD Vision developed and demonstrated a cost-competitiv... more ABSTRACT With DOE Award No. DE-EE00000628, QD Vision developed and demonstrated a cost-competitive solution for increasing the light extraction efficiency of OLEDs with efficient and stable color rendering index (CRI) for solid state lighting (SSL). Solution processable quantum dot (QD) films were integrated into OLED ITO-glass substrates to generate tunable white emission from blue emitting OLED) devices as well as outcouple light from the ITO film. This QD light-enhancement substrate (QD-LED) technology demonstrated a 60% increase in OLED forward light out-coupling, a value which increases to 76% when considering total increase in multi-directional light output. The objective for the first year was an 80% increase in light output. This project seeks to develop and demonstrate a cost-competitive solution for realizing increased extraction efficiency organic light emitting devices (OLEDs) with efficient and stable color rendering index (CRI) for SSL. Solution processible quantum dot (QD) films will be utilized to generate tunable white emission from blue emitting phosphorescent OLED (Ph-OLED) devices.
Nano Letters, 2008
We demonstrate a solvent-free contact printing process for deposition of patterned and unpatterne... more We demonstrate a solvent-free contact printing process for deposition of patterned and unpatterned colloidal quantum dot (QD) thin films as the electroluminescent layers within hybrid organic-QD light-emitting devices (QD-LEDs). Our method benefits from the simplicity, low cost, and high throughput of solution-processing methods, while eliminating exposure of device structures to solvents. Because the charge transport layers in hybrid organic/inorganic QD-LEDs consist of solvent-sensitive organic thin films, the ability to avoid solvent exposure during device growth, as presented in this study, provides a new flexibility in choosing organic materials for improved device performance. In addition, our method allows us to fabricate both monochrome and red-green-blue patterned electroluminescent structures with 25 µm critical dimension, corresponding to 1000 ppi (pixels-per-inch) print resolution.
Sid Symposium Digest of Technical Papers, 2007
Chemical Physics Letters, 2006
We demonstrate exciton energy transfer from a thin film of phosphorescent dye fac tris(2-phenylpy... more We demonstrate exciton energy transfer from a thin film of phosphorescent dye fac tris(2-phenylpyridine) iridium (Ir(ppy) 3 ) to a monolayer of colloidal CdSe/ZnS core/shell quantum dots (QDs). The energy transfer is manifested in time-resolved photoluminescence (PL) measurements as elongation of the QD PL time constant from 40 to 400 ns, and a concomitant 55% increase of time-integrated QD PL intensity. The observed PL dynamics are shown to be dominated by exciton diffusion within the Ir(ppy) 3 film to the QD layer.
Advanced Functional Materials, 2005
Angewandte Chemie International Edition, 2006
Semiconductor nanocrystals (NCs) or quantum dots (QDs) show great promise for use in QD-LED (quan... more Semiconductor nanocrystals (NCs) or quantum dots (QDs) show great promise for use in QD-LED (quantum dot lightemitting device) displays, owing to their unique optical properties and the continual development of new core and core-shell structures to meet specific color needs. This in combination with the recent development of more efficient and saturated QD-LEDs as well as new QD-LED fabrication techniques, suggests that QD-LEDs have the potential to become an alternative flat-panel display technology. The ideal red, green, and blue emission spectrum of an LED for a display application should have a narrow bandwidth and a wavelength such that its color coordinates on the Commission Internationale de lEclairage (CIE) chromaticity diagram lie outside the current National Television System Committee (NTSC) standard color triangle (see ). For a Gaussian emission spectrum with a full width at half maximum (FWHM) of 30 nm and a maximized perceived power, the optimal peak wavelength for display applications is l = 610-620 nm for red, l = 525-530 nm for green, and l = 460-470 nm for blue. For the red pixels, wavelengths longer than l = 620 nm become difficult for the human eye to perceive, while those shorter than l = 610 nm have coordinates that lie inside the standard NTSC color triangle. Optimization of wavelength for the blue pixels follows the same arguments as for the red pixel, but at the other extreme of the visible spectrum. For green pixels, l = 525-530 nm provides a color triangle with the largest area on the CIE chromaticity diagram (and therefore the largest number of colors accessible by a display). Wavelengths longer than l = 530 nm make some of the blue/green area of the triangle inaccessible. Wavelengths shorter than l = 525 nm compromise the yellow display emissions.