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LED types by Color, Brightness, and Chemistry (2021)

19 days ago
https://donklipstein.com/ledc.html
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  • #electronics-history
  • #spectral-analysis
  • #LED-technology
  • LED spectra links updated on Craig Johnson's site with considerations on spectrometer limitations.
  • Original Infrared LED (GaAs) emits at 950 nm, invisible to humans, with a 1.2-1.3V drop.
  • High Efficiency Infrared LED (GaAlAs) from the 1980s emits at 880 nm, slightly visible in dark.
  • Original Visible Red LED (GaAsP) peaks at 660 nm, low efficiency, 1.6-1.75V drop.
  • Low Current Red LED (GaP) efficient at low currents, color shifts with current, 1.9V drop.
  • Super High Brightness Red LED (GaAlAsP) from mid-1980s, 9 lumens/watt, 1.8-1.9V drop.
  • High Efficiency Red/Orange LED (GaAsP on GaP) first non-low-current high-efficiency red LED.
  • Ultrabright Orange-Red to Green LED (InGaAlP) from early 1990s, efficiency varies by color.
  • 2-chip Yellow LED (GaP) from 1976, color varies with current, low efficiency.
  • Silicon Carbide Yellow LED from 1970s Russia, very inefficient.
  • Yellow GaAsP LED, first widespread yellow LED, orangish yellow, low efficiency.
  • High Efficiency Yellow GaAlAsP LED, improved but still not highly efficient.
  • Green LED (GaP), first green LEDs, nitrogen-doped, yellowish green, low efficiency.
  • High Efficiency Green LED (GaAlP), similar to GaP but higher efficiency (~1 lumen/watt).
  • "Pure Green" LED (GaP), less yellow, very low efficiency (<0.1 lumen/watt).
  • InGaN Ultrabright Blue/Green LED, dominant wavelengths 470 nm (blue) and 525-527 nm (green).
  • White LEDs use blue LED with phosphor, efficacy improved from 7.5 to 30+ lumens/watt by 2006.
  • Wideband GaN Blue LED, first ultrabright blue, ~3 lumens/watt, spectrum from violet to green.
  • Silicon Carbide Blue LED, original commercial blue LED by Cree, turquoise, low efficiency.
  • Violetish Blue GaN LED (Cree), broadband, intense color, ~0.5 lumen/watt.
  • UV LEDs by Nichia peak at 370-375 nm, others up to 405 nm, limited lifespan due to epoxy degradation.
  • Pink/Purple LEDs use phosphor layers over blue LEDs, some face fading issues.
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