Advancing toward pure white LED

[Calina]

Here is the latest development in white LED thechnology:

http://www.sciencedaily.com/releases/2007/09/070924094936.htm

http://pubs.acs.org/doi/abs/10.1021/ja902533f

When will it leak into production?
Place your bets...

 

[Sub_Umbra]

"Proof of Principle" for True White Emitter

A White-Light-Emitting Molecule

 

[Sgt. LED]

Re: "Proof of Principle" for True White Emitter

Thought provoking abstract. Wish I could read all of it.

It seems that I can rent access to the full text for 2 days for only $30. What a deal.

 

[jtr1962]

Re: "Proof of Principle" for True White Emitter

Here's a little more about this.

Looks promising. It would be nice to finally not have to worry about tints.

 

[Calina]

Re: "Proof of Principle" for True White Emitter

I started a thread about this last week: http://www.candlepowerforums.com/vb/showthread.php?t=234554

 

[wapkil]

Re: "Proof of Principle" for True White Emitter

Thought provoking abstract. Wish I could read all of it.

It seems that I can rent access to the full text for 2 days for only $30. What a deal.

Well, what they did is actually quite simple. They designed a "single molecular dyad composed of two ESIPT moieties in place of ordinary fluorescent materials. Each ESIPT moiety is characterized by a fast enol (E) to keto (K) cyclic intramolecular phototautomerization and demonstrates a high-energy UV enol absorption coupled with tunable keto emission"

Obviously "orange keto-emitting ESIPT unit was successfully synthesized by replacing the phenyl group of HPI by the naphthalene group [3-(1,4,5-triphenyl-1H-imidazol-2-yl)naphthalen-2-ol (HPNI)]"

as you probably expected:

"in the newly synthesized HPNI molecule, the naphthalene group significantly stabilized the energy of the excited-state keto form by enhancement of conjugation via delocalization of electrons along the naphthalene backbone"


It requires "a little" more chemical knowledge than I have to even decipher what's written there. But I understood that their molecules are probably somehow better than other ones

 

[Sub_Umbra]

Re: "Proof of Principle" for True White Emitter

Thanks for the additional links, guys.

 

[mudman cj]

Re: "Proof of Principle" for True White Emitter

IMO this article has a more accessible explanation.

Quoting from this linked article:

"Previous attempts using the same basic concept involved linking together two separate molecules into one. But, because energy is able to flow between the two molecular sub-units, one unit typically emits more light than the other, resulting in an unwanted tint. The new molecule does not suffer that problem, and only contains one light-emitting chemical group. When connected to a voltage, this group switches to a high-energy form that emits blue light as it reverts to its original state.
Roughly half the time, though, the high-energy form picks up extra oxygen and hydrogen atoms, becoming a short-lived form that produces orange light before reverting to the original state.
A large population of the molecules reliably produces equal quantities of orange and blue light that mix to produce an even white."


This explains why this molecule is 'better' than previous ones, but note that it has a long way yet to go. Compared to current LED phosphors, it is only 1/30 of the efficiency.

 

[blasterman]

Re: "Proof of Principle" for True White Emitter

Compared to current LED phosphors, it is only 1/30 of the efficiency.

I'm sure Phillips is all over it

 

[DM51]

Re: "Proof of Principle" for True White Emitter

Merging threads...

 

[Calina]

Re: "Proof of Principle" for True White Emitter

Merging threads...

Thank you.