Talk:Light-emitting diode

LEDs don't NEED

"other components to work". section in question: LEDs usually need electronic support components to function, while an incandescent bulb can and usually does operate directly from an unregulated DC or AC power source.[citation needed]

just remove it because it's wrong and gives a false impression. Or could atleast be worded differently. SOME LEDs require other components to work MORE efficiently, while others don't require additional components to work. Some LEDs are designed for the range of 1.5-4.0VDC range and those will work directly to battery power.. unless components = power supply as well.. 24.19.141.129 (talk) 00:08, 28 April 2023 (UTC)

One can build a device with a current regulator inside, or even just a resistor. Many are commonly run of small button cell batteries, (or two or three), relying on the internal resistance of the battery. The claim is wrong for incandescent lamps, as they need a somewhat regulated power source. The whole AC power distribution system is designed to regulate voltage enough for them. (Usually tap switching distribution transformers.) Do you have a reference for the 1.5V to 4.0V LED? Gah4 (talk) 08:37, 8 August 2023 (UTC)

PIV

LEDs commonly have a reverse voltage limit in the 5V range. Enough to allow easy multiplexing. For AC operation, you usually need a series silicon diode. A typical data sheet is here. Gah4 (talk) 08:40, 8 August 2023 (UTC)

Reverse voltage and various clarifications.

First we might need clarification as to what LED refers to. Is it:

• is it a single crystal (i.e. a single P-N junction)
• is it an electronic component, which in most cases includes a single PN junction but can include more than one (e.g a bicolor LED), or include a resistor for current limitation (hence the rating of some LEDs as 5V for instance).

For the rest of this comment I am going to assume an LED is a single P-N junction.

Regarding reverse voltage: Most if not all LED manufacturers will list an absolute maximum reverse voltage as 5V. Yet, many people are driving LEDs directly from an AC power line (120V or 240V) with a resistor for current limiting. And in this case, an LED is subjected to a reverse voltage of √2 x 240 ≈ 339V at its peak, a much higher value than 5V. And I have never seen an LED being damaged for that reason. So, I have been trying to figure why there is such an apparent huge discrepancy between what manufacturers recommend and what reality allows. In other words, why do manufacturers list 5V, when you can obviously go much higher, unlike most other absolute maximum ratings which have a much smaller safety margin. I have found a few hints, but nothing that definitely explains that difference. Does anyone know? and should that be mentioned in the article? Dhrm77 (talk) 12:35, 2 November 2023 (UTC)

I did used to drive them directly from 120VAC, but with a series silicon diode. I never tested them for PIV, though. If you have a current limited adjustable source, you can measure the reverse breakdown. Gah4 (talk) 00:14, 4 March 2024 (UTC)

Allen-Cherry 1961 paper - does not report on light emission

I've read the 1961 Allen & Cherry paper cited in this article. The sentence claiming that this paper reports on light emission isn't correct - that paper mostly discusses photoconductivity. I'll delete the sentence in a day or so. It is possible that Allen & Cherry did observed light emission around then, but that important claim is not backed up by the reference. Easchiff (talk) 03:22, 8 January 2024 (UTC)

This paragraph of the article has been revised to expand on the GaAsP devices that were the first visible light LEDs to be commercialized. The full history of visible light LEDs is complex, and there is further discussion later in the article. Easchiff (talk) 15:43, 14 January 2024 (UTC)

"Despite not the inventors of the blue LED..."

This proposed wording would require much better sources to include. The term "inventors" is vague and can have many different meanings, so it's not necessarily obvious what is meant here; and "despite" carries a WP:SYNTHy connection to the award, as though it is somehow of great import that they were awarded it for efficient blue LEDs. Making that connection would require a source saying something roughly comparable. The article already notes the full history of the development of the blue LED, which makes clear what their contribution was; but highlighting this aspect with a "despite" and categorically declaring them to not be the inventors isn't appropriate without a secondary source. --Aquillion (talk) 13:51, 10 February 2024 (UTC)

What I've heard that Shuji Nakamura, Hiroshi Amano and Isamu Akasaki, were awarded the prize for the blue LED, not specificantly for the high brightness blue LED. and the information before the awards section, is enough to prove that the Nobel prize in physics 2014 was awarded to the wrong people. זור987 (talk) 14:05, 10 February 2024 (UTC)

That sounds like WP:RIGHTGREATWRONGS. We definitely can't say or imply that the award itself was awarded to the wrong people unless we have sources supporting that explicitly. Even if they did get it wrong, Wikipedia isn't the place to try and correct that; we're an encyclopedia, so we summarize what other sources say - trying to "prove it" yourself is WP:SYNTH / WP:OR. --Aquillion (talk) 14:47, 10 February 2024 (UTC)

There were, many years ago, experiments with SiC. It was extremely inefficient, so didn't count as an actual LED, at least not for commercial use. The efficient statement is important. That might compare to 0.01% efficient or so. Gah4 (talk) 00:17, 4 March 2024 (UTC)

Table needed

A table is needed showing the emitted colour of an LED versus things such as typical voltage required, doping material used... 2001:8003:E40F:9601:4D90:A972:FCCB:FA19 (talk) 06:12, 3 March 2024 (UTC)

It mostly doesn't depend on the doping, but the actual semiconductor material. Often they are alloys, such as the early GaAsP, which is a crystal mixture of GaAs and GaP, and with gap somewhere in between. But yes, a table would be nice, at least for the common cases. Gah4 (talk) 00:19, 4 March 2024 (UTC)