Fluorescent/Phosphorescent Dopants - Revision history

Cmditradmin: /* Increasing Performance */

2010-08-09T18:52:24Z

Increasing Performance

← Older revision		Revision as of 11:52, 9 August 2010
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	You can also increase device performance by increasing Φ using energy transfer. Consider the dynamics of Förster energy transfer. Spin statistics dictate that 75% of the electron transfer is in the triplet state. In the case of emission, the singlet state gives you fluorescence, and phosphorescence comes from the decay of the triplets state back to the ground state. It would be best to capture the energy from both states. Energy efficiency is strongly dependent on the overlap of donor emission with acceptor absorbance.		You can also increase device performance by increasing Φ using energy transfer. Consider the dynamics of Förster energy transfer. Spin statistics dictate that 75% of the electron transfer is in the triplet state. In the case of emission, the singlet state gives you fluorescence, and phosphorescence comes from the decay of the triplets state back to the ground state. It would be best to capture the energy from both states. Energy efficiency is strongly dependent on the overlap of donor emission with acceptor absorbance.

	See ~~Wikipedia on Förster transfer<ref>http~~:~~//en.wikipedia.org/wiki/~~Fluorescence_resonance_energy_transfer~~</ref>~~		See [[wikipedia:Fluorescence_resonance_energy_transfer]]
	<br clear="all">		<br clear="all">
	[[Image:Phosphorescent dopants.JPG\|thumb\|400px\|Phosphorescent doping increases the amount of intersystem crossing]]		[[Image:Phosphorescent dopants.JPG\|thumb\|400px\|Phosphorescent doping increases the amount of intersystem crossing]]

Cmditradmin at 22:33, 26 April 2010

2010-04-26T22:33:08Z

← Older revision		Revision as of 15:33, 26 April 2010
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	<references/>		<references/>
	[[category:organic LED]]		[[category:organic LED]]
	[[category:~~luminencence~~]]		[[category:luminescence]]
	<table id="toc" style="width: 100%">		<table id="toc" style="width: 100%">
	<tr>		<tr>

Cmditradmin at 20:14, 29 December 2009

2009-12-29T20:14:35Z

← Older revision		Revision as of 13:14, 29 December 2009
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	<references/>		<references/>
			[[category:organic LED]]
	[[category:luminencence]]		[[category:luminencence]]
	<table id="toc" style="width: 100%">		<table id="toc" style="width: 100%">

Cmditradmin at 20:14, 29 December 2009

2009-12-29T20:14:15Z

← Older revision		Revision as of 13:14, 29 December 2009
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	[[Image:OLED9_ptoep_efficiency.JPG\|thumb\|400px\|Quantum efficiency drops off at higher current density.]]		[[Image:OLED9_ptoep_efficiency.JPG\|thumb\|400px\|Quantum efficiency drops off at higher current density.]]
	It is important to look at the quantum efficiency for these devices as a function of the applied current density. The optimal system will maximize light output while minimizing the current injected into the system. At a threshold luminance of 100 candelas per square meter (about the about the intensity of a computer screen display), PtOEP has a quantum efficiency of 1% and current density of 10 mA per square centimeter. This is not bad but could be better. PtOEP might not be the best choice for an emitter because of its long lifetime of 100 microseconds. Some energy will be lost through this phosphorescence because it lasts so long and there are other non-radiative decay processes that suck energy away.		It is important to look at the quantum efficiency for these devices as a function of the applied current density. The optimal system will maximize light output while minimizing the current injected into the system. At a threshold luminance of 100 candelas per square meter (about the about the intensity of a computer screen display), PtOEP has a quantum efficiency of 1% and current density of 10 mA per square centimeter. This is not bad but could be better. PtOEP might not be the best choice for an emitter because of its long lifetime of 100 microseconds. Some energy will be lost through this phosphorescence because it lasts so long and there are other non-radiative decay processes that suck energy away.
	~~[[category:organic LED]]~~
	<br clear='all'>		<br clear='all'>

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	<references/>		<references/>

			[[category:luminencence]]
	<table id="toc" style="width: 100%">		<table id="toc" style="width: 100%">
	<tr>		<tr>

128.95.39.42: /* Increasing Performance */

2009-12-17T21:29:06Z

Increasing Performance

← Older revision		Revision as of 14:29, 17 December 2009
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	[[Image:Phosphorescent dopants.JPG\|thumb\|400px\|Phosphorescent doping increases the amount of intersystem crossing]]		[[Image:Phosphorescent dopants.JPG\|thumb\|400px\|Phosphorescent doping increases the amount of intersystem crossing]]

	Because of the weak probability of intersystem crossing from fluorescent to the phosphorescent triplet state these molecules have lifetimes that are milliseconds long. ~~Diplay~~ devices such as OLEDs need to have lifetimes that are shorter.		Because of the weak probability of intersystem crossing from fluorescent to the phosphorescent triplet state these molecules have lifetimes that are milliseconds long. Display devices such as OLEDs need to have lifetimes that are shorter.

	Phosphorescent dopants such as the heavy metal porphyrin PtOEP can increase efficiency to 5%. The heavy metal increases the probability of intersystem crossing.		Phosphorescent dopants such as the heavy metal porphyrin PtOEP can increase efficiency to 5%. The heavy metal increases the probability of intersystem crossing.

Cmditradmin: /* Excited States of Organometallic Complexes */

2009-12-01T23:18:01Z

Excited States of Organometallic Complexes

← Older revision		Revision as of 16:18, 1 December 2009
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	<br clear="all">		<br clear="all">
	[[Image:OLED9_ptoep_efficiency.JPG\|thumb\|400px]Quantum efficiency drops off at higher current density.]		[[Image:OLED9_ptoep_efficiency.JPG\|thumb\|400px\|Quantum efficiency drops off at higher current density.]]
	It is important to look at the quantum efficiency for these devices as a function of the applied current density. The optimal system will maximize light output while minimizing the current injected into the system. At a threshold luminance of 100 candelas per square meter (about the about the intensity of a computer screen display), PtOEP has a quantum efficiency of 1% and current density of 10 mA per square centimeter. This is not bad but could be better. PtOEP might not be the best choice for an emitter because of its long lifetime of 100 microseconds. Some energy will be lost through this phosphorescence because it lasts so long and there are other non-radiative decay processes that suck energy away.		It is important to look at the quantum efficiency for these devices as a function of the applied current density. The optimal system will maximize light output while minimizing the current injected into the system. At a threshold luminance of 100 candelas per square meter (about the about the intensity of a computer screen display), PtOEP has a quantum efficiency of 1% and current density of 10 mA per square centimeter. This is not bad but could be better. PtOEP might not be the best choice for an emitter because of its long lifetime of 100 microseconds. Some energy will be lost through this phosphorescence because it lasts so long and there are other non-radiative decay processes that suck energy away.
	[[category:organic LED]]		[[category:organic LED]]

Cmditradmin: /* Excited States of Organometallic Complexes */

2009-12-01T19:11:40Z

Excited States of Organometallic Complexes

← Older revision		Revision as of 12:11, 1 December 2009
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	==Excited States of Organometallic Complexes==		==Excited States of Organometallic Complexes==
	[[Image:organometalliccomplex.JPG\|thumb\|400px]Ligand to Metal Charge Transfer (LMCT) compared to Metal to Ligand Charge Transfer (MLCT) with Metal Centered (MC) and Ligand Centered (LC)]		[[Image:organometalliccomplex.JPG\|thumb\|400px\|Ligand to Metal Charge Transfer (LMCT) compared to Metal to Ligand Charge Transfer (MLCT) with Metal Centered (MC) and Ligand Centered (LC)]]
	There are a couple of considerations when you work with organometallic complexes. There are ligand to metal transitions in the absorption of these molecules. There are ligand centered transitions, metal to ligand centered, and metal centered transitions. One must understand which of the molecular orbitals you are going to use to maximize the triplet state and the phosphorescence.		There are a couple of considerations when you work with organometallic complexes. There are ligand to metal transitions in the absorption of these molecules. There are ligand centered transitions, metal to ligand centered, and metal centered transitions. One must understand which of the molecular orbitals you are going to use to maximize the triplet state and the phosphorescence.

Cmditradmin: /* Excited States of Organometallic Complexes */

2009-12-01T19:10:49Z

Excited States of Organometallic Complexes

← Older revision		Revision as of 12:10, 1 December 2009
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	==Excited States of Organometallic Complexes==		==Excited States of Organometallic Complexes==
	[[Image:organometalliccomplex.JPG\|thumb\|400px]]		[[Image:organometalliccomplex.JPG\|thumb\|400px]Ligand to Metal Charge Transfer (LMCT) compared to Metal to Ligand Charge Transfer (MLCT) with Metal Centered (MC) and Ligand Centered (LC)]
	There are a couple of considerations when you work with organometallic complexes. There are ligand to metal transitions in the absorption of these molecules. There are ligand centered transitions, metal to ligand centered, and metal centered transitions. One must understand which of the molecular orbitals you are going to use to maximize the triplet state and the phosphorescence.		There are a couple of considerations when you work with organometallic complexes. There are ligand to metal transitions in the absorption of these molecules. There are ligand centered transitions, metal to ligand centered, and metal centered transitions. One must understand which of the molecular orbitals you are going to use to maximize the triplet state and the phosphorescence.

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	<br clear="all">		<br clear="all">
	[[Image:OLED9_ptoep_efficiency.JPG\|thumb\|400px]]		[[Image:OLED9_ptoep_efficiency.JPG\|thumb\|400px]Quantum efficiency drops off at higher current density.]
	It is important to look at the quantum efficiency for these devices as a function of the applied current density. The optimal system will maximize light output while minimizing the current injected into the system. At a threshold luminance of 100 candelas per square meter (about the about the intensity of a computer screen display), PtOEP has a quantum efficiency of 1% and current density of 10 mA per square centimeter. This is not bad but could be better. PtOEP might not be the best choice for an emitter because of its long lifetime of 100 microseconds. Some energy will be lost through this phosphorescence because it lasts so long and there are other non-radiative decay processes that suck energy away.		It is important to look at the quantum efficiency for these devices as a function of the applied current density. The optimal system will maximize light output while minimizing the current injected into the system. At a threshold luminance of 100 candelas per square meter (about the about the intensity of a computer screen display), PtOEP has a quantum efficiency of 1% and current density of 10 mA per square centimeter. This is not bad but could be better. PtOEP might not be the best choice for an emitter because of its long lifetime of 100 microseconds. Some energy will be lost through this phosphorescence because it lasts so long and there are other non-radiative decay processes that suck energy away.
	[[category:organic LED]]		[[category:organic LED]]
	<br clear='all'>		<br clear='all'>

	== References ==		== References ==

Cmditradmin: /* Device Efficiency */

2009-07-23T22:35:10Z

Device Efficiency

← Older revision		Revision as of 15:35, 23 July 2009
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	where		where

	:<math>\phi_R\,\!</math> is Langevin ~~recombination~~ efficiency		:<math>\phi_R\,\!</math> is Langevin Recombination efficiency

	:<math>\phi_S\,\!</math> is Singlet ~~triplet branching~~ efficiency		:<math>\phi_S\,\!</math> is Singlet Triplet Branching efficiency

	:<math>\phi_F\,\!</math> is Fluorescent efficiency		:<math>\phi_F\,\!</math> is Fluorescent efficiency

	:<math>\phi_R\,\!</math> is External ~~coupling~~ efficiency		:<math>\phi_R\,\!</math> is External Coupling efficiency

	==Increasing Performance==		==Increasing Performance==

Cmditradmin: /* Device Efficiency */

2009-07-23T22:31:52Z

Device Efficiency

← Older revision		Revision as of 15:31, 23 July 2009
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	The quantum efficiency ~~Φ~~ can be ~~expressed~~		The quantum efficiency can also be written

	:<math>\phi = \phi_R \cdot \phi_S \cdot \phi_F \cdot \phi_E\,\!</math>		:<math>\phi = \phi_R \cdot \phi_S \cdot \phi_F \cdot \phi_E\,\!</math>
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	where		where

	:<math>\phi_R\,\!</math> is Langevin recombination		:<math>\phi_R\,\!</math> is Langevin recombination efficiency

	:<math>\phi_S\,\!</math> is Singlet triplet branching		:<math>\phi_S\,\!</math> is Singlet triplet branching efficiency

	:<math>\phi_F\,\!</math> is Fluorescent		:<math>\phi_F\,\!</math> is Fluorescent efficiency

	:<math>\phi_R\,\!</math> is External coupling		:<math>\phi_R\,\!</math> is External coupling efficiency

	==Increasing Performance==		==Increasing Performance==