Light Emitting Electrochemical Processes - Revision history

Cmditradmin: /* The Jablonski Diagram */

2010-07-21T22:44:59Z

The Jablonski Diagram

← Older revision		Revision as of 15:44, 21 July 2010
Line 25:		Line 25:

	[[Image:Jablonski.jpg\|thumb\|400px\|Jablonski diagram for chemiluminence ]]		[[Image:Jablonski.jpg\|thumb\|400px\|Jablonski diagram for chemiluminence ]]
	The [[Jablonksi]] diagram is a simple way to describe what is happening with small molecules and small conjugated aromatic systems. It describes the energy (wavelength) of absorbance and luminescence for aromatic molecules.		The [[Jablonksi Diagram]] diagram is a simple way to describe what is happening with small molecules and small conjugated aromatic systems. It describes the energy (wavelength) of absorbance and luminescence for aromatic molecules.
	<gallery heights=200px widths=300px perrow =3>		<gallery heights=200px widths=300px perrow =3>
	Image:Oled1 8 jablonski.png\|First, a photon is absorbed. Excited singlets are created with different vibronic excited levels. These are the vibronic levels associated with the population of the the ν=1, ν=2 levels.		Image:Oled1 8 jablonski.png\|First, a photon is absorbed. Excited singlets are created with different vibronic excited levels. These are the vibronic levels associated with the population of the the ν=1, ν=2 levels.

Cmditradmin: /* Light Emission from Recombination */

2010-07-07T20:09:33Z

Light Emission from Recombination

← Older revision		Revision as of 13:09, 7 July 2010
Line 22:		Line 22:

	We can write this from the point of view of a homogenous electrochemical process. At the same time this was being done in the condensed phase people were beginning to explore this process in solution. Rudy Marcus used this as a central tenant in his development of electron transfer theory between small molecule systems.		We can write this from the point of view of a homogenous electrochemical process. At the same time this was being done in the condensed phase people were beginning to explore this process in solution. Rudy Marcus used this as a central tenant in his development of electron transfer theory between small molecule systems.
			== The Jablonski Diagram==

	[[Image:~~== The Jablonski Diagram==~~		[[Image:Jablonski.jpg\|thumb\|400px\|Jablonski diagram for chemiluminence ]]
	Jablonski.jpg\|thumb\|400px\|Jablonski diagram for chemiluminence ]]
	The [[Jablonksi]] diagram is a simple way to describe what is happening with small molecules and small conjugated aromatic systems. It describes the energy (wavelength) of absorbance and luminescence for aromatic molecules.		The [[Jablonksi]] diagram is a simple way to describe what is happening with small molecules and small conjugated aromatic systems. It describes the energy (wavelength) of absorbance and luminescence for aromatic molecules.
	<gallery heights=200px widths=300px perrow =3>		<gallery heights=200px widths=300px perrow =3>

Cmditradmin: /* The Jablonski Diagram */

2010-07-07T20:08:26Z

The Jablonski Diagram

← Older revision		Revision as of 13:08, 7 July 2010
Line 23:		Line 23:
	We can write this from the point of view of a homogenous electrochemical process. At the same time this was being done in the condensed phase people were beginning to explore this process in solution. Rudy Marcus used this as a central tenant in his development of electron transfer theory between small molecule systems.		We can write this from the point of view of a homogenous electrochemical process. At the same time this was being done in the condensed phase people were beginning to explore this process in solution. Rudy Marcus used this as a central tenant in his development of electron transfer theory between small molecule systems.

	== The Jablonski Diagram==		[[Image:== The Jablonski Diagram==
			Jablonski.jpg\|thumb\|400px\|Jablonski diagram for chemiluminence ]]
	The [[Jablonksi]] diagram is a simple way to describe what is happening with small molecules and small conjugated aromatic systems. It describes the energy (wavelength) of absorbance and luminescence for aromatic molecules.		The [[Jablonksi]] diagram is a simple way to describe what is happening with small molecules and small conjugated aromatic systems. It describes the energy (wavelength) of absorbance and luminescence for aromatic molecules.
	<gallery heights=200px widths=300px perrow =3>		<gallery heights=200px widths=300px perrow =3>
Line 34:		Line 35:
	</gallery>		</gallery>
	Most molecules have lifetimes of 1-100 microseconds. Compounds that are most useful for OLEDs have lifetimes closer to 1 microsecond. Most people are familiar with molecules that phosphoresce with much longer lifetimes and have emission events at much longer wavelengths, making them less useful for displays.		Most molecules have lifetimes of 1-100 microseconds. Compounds that are most useful for OLEDs have lifetimes closer to 1 microsecond. Most people are familiar with molecules that phosphoresce with much longer lifetimes and have emission events at much longer wavelengths, making them less useful for displays.


	==Color of Absorption and Emission ==		==Color of Absorption and Emission ==

Cmditradmin at 19:59, 7 July 2010

2010-07-07T19:59:56Z

← Older revision		Revision as of 12:59, 7 July 2010
Line 71:		Line 71:
	<td style="text-align: left; width: 33%">[[OLED Device Applications\|Previous Topic]]</td>		<td style="text-align: left; width: 33%">[[OLED Device Applications\|Previous Topic]]</td>
	<td style="text-align: center; width: 33%">[[Main_Page#Organic_Light_Emitting_Diodes\|Return to OLED Menu]]</td>		<td style="text-align: center; width: 33%">[[Main_Page#Organic_Light_Emitting_Diodes\|Return to OLED Menu]]</td>
	<td style="text-align: right; width: 33%">[[The OLED ~~test cell~~\|Next Topic]]</td>		<td style="text-align: right; width: 33%">[[The OLED Test Cell\|Next Topic]]</td>
	</tr>		</tr>
	</table>		</table>

Cmditradmin at 16:55, 3 September 2009

2009-09-03T16:55:39Z

← Older revision		Revision as of 09:55, 3 September 2009
Line 7:		Line 7:
	</table>		</table>

			Light emission in the OLED arises from recombination (electron transfer) reactions of the cation and anion radical of conjugated aromatic molecules.
			== Light Emission from Recombination==


	~~This article serves as an introduction to the design and chemistry of organic light emitting diodes (OLEDs).~~

	~~== Light Emission from Recombination==~~
	~~Light emission in the OLED arises from recombination (electron transfer) reactions of the cation and anion radical of conjugated aromatic molecules.~~
	Several decades ago it was noted that poly(acenes) and related poly-aromatic hydrocarbons, in very dry nonaqueous (non-polar) solvents can be reduced by one electron (chemically or electrochemically) to produce an energetic radical anion state (D<sup>-.</sup>). These same molecules can often be oxidized by one electron to produce a cation radical state (A<sup>+.</sup>).		Several decades ago it was noted that poly(acenes) and related poly-aromatic hydrocarbons, in very dry nonaqueous (non-polar) solvents can be reduced by one electron (chemically or electrochemically) to produce an energetic radical anion state (D<sup>-.</sup>). These same molecules can often be oxidized by one electron to produce a cation radical state (A<sup>+.</sup>).
	Should A<sup>+.</sup> and D<sup>-.</sup> encounter each other in solution, a “recombination” electron transfer reaction occurs. The excess free energy in this reaction can be deposited in one of the molecular species to form its lowest excited state (singlet), or in some cases, its lowest triplet excited state. These states are the same as those created by photoexcitation of the molecule. Emission from this state occurs with a lifetime of nanoseconds, with [[Definition: Quantum Yield\|quantum yields]] approaching 100% in some cases.		Should A<sup>+.</sup> and D<sup>-.</sup> encounter each other in solution, a “recombination” electron transfer reaction occurs. The excess free energy in this reaction can be deposited in one of the molecular species to form its lowest excited state (singlet), or in some cases, its lowest triplet excited state. These states are the same as those created by photoexcitation of the molecule. Emission from this state occurs with a lifetime of nanoseconds, with [[Definition: Quantum Yield\|quantum yields]] approaching 100% in some cases.

Cmditradmin: /* Light Emission from Recombination */

2009-09-03T15:42:29Z

Light Emission from Recombination

← Older revision		Revision as of 08:42, 3 September 2009
Line 22:		Line 22:


	~~[[Image:Ecl-redox.gif‎\|400px\|The complete sequence.]]~~
	<br clear="all">		<br clear="all">

128.95.39.55 at 19:47, 24 June 2009

2009-06-24T19:47:20Z

← Older revision		Revision as of 12:47, 24 June 2009
Line 3:		Line 3:
	<td style="text-align: left; width: 33%">[[OLED Device Applications\|Previous Topic]]</td>		<td style="text-align: left; width: 33%">[[OLED Device Applications\|Previous Topic]]</td>
	<td style="text-align: center; width: 33%">[[Main_Page#Organic_Light_Emitting_Diodes\|Return to OLED Menu]]</td>		<td style="text-align: center; width: 33%">[[Main_Page#Organic_Light_Emitting_Diodes\|Return to OLED Menu]]</td>
	<td style="text-align: right; width: 33%">[[The OLED ~~test cell~~\|Next Topic]]</td>		<td style="text-align: right; width: 33%">[[The OLED Test Cell\|Next Topic]]</td>
	</tr>		</tr>
	</table>		</table>

128.95.39.55 at 19:46, 24 June 2009

2009-06-24T19:46:49Z

← Older revision		Revision as of 12:46, 24 June 2009
Line 13:		Line 13:
	== Light Emission from Recombination==		== Light Emission from Recombination==
	Light emission in the OLED arises from recombination (electron transfer) reactions of the cation and anion radical of conjugated aromatic molecules.		Light emission in the OLED arises from recombination (electron transfer) reactions of the cation and anion radical of conjugated aromatic molecules.
	Several decades ago it was noted that poly(acenes) and related poly-aromatic hydrocarbons, in very dry nonaqueous (non-polar) solvents can be reduced by one electron (chemically or electrochemically) to produce an energetic radical anion state (D<sup>-</sup>). These same molecules can often be oxidized by one electron to produce a cation radical state (A<sup>+</sup>).		Several decades ago it was noted that poly(acenes) and related poly-aromatic hydrocarbons, in very dry nonaqueous (non-polar) solvents can be reduced by one electron (chemically or electrochemically) to produce an energetic radical anion state (D<sup>-.</sup>). These same molecules can often be oxidized by one electron to produce a cation radical state (A<sup>+.</sup>).
	Should A<sup>+</sup> and D<sup>-</sup> encounter each other in solution, a “recombination” electron transfer reaction occurs. The excess free energy in this reaction can be deposited in one of the molecular species to form its lowest excited state (singlet), or in some cases, its lowest triplet excited state. These states are the same as those created by photoexcitation of the molecule. Emission from this state occurs with a lifetime of nanoseconds, with [[Definition: Quantum Yield\|quantum yields]] approaching 100% in some cases.		Should A<sup>+.</sup> and D<sup>-.</sup> encounter each other in solution, a “recombination” electron transfer reaction occurs. The excess free energy in this reaction can be deposited in one of the molecular species to form its lowest excited state (singlet), or in some cases, its lowest triplet excited state. These states are the same as those created by photoexcitation of the molecule. Emission from this state occurs with a lifetime of nanoseconds, with [[Definition: Quantum Yield\|quantum yields]] approaching 100% in some cases.
	These “electrogenerated chemiluminescence” (ECL) processes are direct analogues of the charge recombination processes which occur in the condensed phase in an OLED. They are also closely related to the chemiluminescence and bioluminescence processes which occur in living organisms such as fireflies.		These “electrogenerated chemiluminescence” (ECL) processes are direct analogues of the charge recombination processes which occur in the condensed phase in an OLED. They are also closely related to the chemiluminescence and bioluminescence processes which occur in living organisms such as fireflies.

Line 54:		Line 54:

	Image:Oled1_15_phosphor.png\|Phosphorescence with linked systems		Image:Oled1_15_phosphor.png\|Phosphorescence with linked systems
	Image:Oled1_19_jablonski ratio.png\|During electrochemical excitation of these systems, 25% of the energy is deposited as singlet states, and 75%of the energy is deposited as triplet states. This significantly impacts the optimization of OLEDs which use either fluorescent molecules or phosphorescent dopants to create light. The use of phosphorescent dopants has increased efficiency to the near fluorescent lighting levels.		Image:Oled1_19_jablonski ratio.png\|During electrochemical excitation of these systems, 25% of the energy is deposited as singlet states, and 75% of the energy is deposited as triplet states. This significantly impacts the optimization of OLEDs which use either fluorescent molecules or phosphorescent dopants to create light. The use of phosphorescent dopants has increased efficiency to the near fluorescent lighting levels.
	</gallery>		</gallery>

Smhunter at 21:25, 23 June 2009

2009-06-23T21:25:42Z

← Older revision		Revision as of 14:25, 23 June 2009
Line 28:		Line 28:

	== The Jablonski Diagram==		== The Jablonski Diagram==
	The [[Jablonksi]] diagram is a simple way to describe what is happening with small molecules and small conjugated aromatic systems. ~~The Jablonski diagram is used to describe~~ the energy (wavelength) of absorbance and luminescence for aromatic molecules.		The [[Jablonksi]] diagram is a simple way to describe what is happening with small molecules and small conjugated aromatic systems. It describes the energy (wavelength) of absorbance and luminescence for aromatic molecules.
	<gallery heights=200px widths=300px perrow =3>		<gallery heights=200px widths=300px perrow =3>
	Image:Oled1 8 jablonski.png\|First, a photon is absorbed. Excited singlets are created with different vibronic excited levels. These are the vibronic levels associated with the population of the the ν=1 , ν =2 levels.		Image:Oled1 8 jablonski.png\|First, a photon is absorbed. Excited singlets are created with different vibronic excited levels. These are the vibronic levels associated with the population of the the ν=1, ν=2 levels.
	Image:Oled1 10 absorbance.png\|This shows the absorption spectra with its associated fine structure. This is the lowest energy of the absorption bands.		Image:Oled1 10 absorbance.png\|This shows the absorption spectra with its associated fine structure. This is the lowest energy of the absorption bands.
	Image:Oled1_9_relaxation.png\|That is followed by very fast non-radiative relaxation.		Image:Oled1_9_relaxation.png\|That is followed by very fast non-radiative relaxation.

Cmditradmin at 15:32, 11 June 2009

2009-06-11T15:32:56Z

← Older revision		Revision as of 08:32, 11 June 2009
Line 7:		Line 7:
	</table>		</table>

	~~[[Main_Page#Organic_Light_Emitting_Diodes\|Return to OLED Menu]] \| [[The OLED test cell\|Next Topic]]~~