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I keep seeing all kinds of objects now having small but very bright LED lights in them, seemingly never burning out, requiring almost no batteries/power, and extremely durable.

I remember being a child in the 1990s and the typical flashlights you could buy were extremely crude in comparison: huge, bulky, metallic, heavy, requiring many large batteries, and requiring the light bulb in it to be replaced. And it barely made much light.

Now, they seem to be able to put a bright LED into any small object which shines way more.

How did that happen? The technology "LED lights" must have existed for many decades prior to the 1990s, even. So why is everything just recently using them?

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  • $\begingroup$ Basically the npn or pnp junction, quality and purity. $\endgroup$
    – Solar Mike
    Jan 27 at 19:52
  • $\begingroup$ Don't forget that the cost of such things isn't as high anymore due to the improvements on the criteria Solar Mike listed. $\endgroup$
    – J. Ari
    Jan 27 at 20:16
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    $\begingroup$ The blue led was invented in 1990. Before that there was no good basis for making a white led, because you need blue to complete the spectrum. But it took some time to make the lights good looking white and make the manufacturing processes cheap enough for mass consumption. So yes led lights existed before just not white ones, and that is what you care about really. $\endgroup$
    – joojaa
    Jan 27 at 20:33
  • $\begingroup$ @SolarMike, why PNP / NPN? There's only one junction per LED, isn't there? $\endgroup$
    – Transistor
    Jan 27 at 23:33
  • $\begingroup$ @Transistor just because most have heard of those and if I just said it was a doped crystal I would have been asked for the supplier... $\endgroup$
    – Solar Mike
    Jan 28 at 5:34
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The biggest hurdle was the white light LEDs, which were first available commercially in 1996-1997, a few years after the blue light (1994) .

The following image compares all types of lighting

enter image description here

An 2018 article for Historical perspective on the physics of artificial lighting addresses many of your questions, and has the following image which summarises the material technologies involved.

enter image description here

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