Photometric characterization of OLEDs1
1. General definitions ď Ž
dW W Energetic flux (radiant): ÎŚ e = e , if the flux is uniform over time ‘t’ then ÎŚ e = e and is t dt expressed in watts (W).
ď Ž
Luminous flux ÎŚ v is defined with respect to the sensitivity of the human eye to different wavelengths of light. The value is expressed in lumen (lm). To convert from energetic to luminous scales the constant Km = 683 lm W-1 is multiplied by the diurnal photo-response V(đ?œ†đ?œ†) of human eye. ď Ź V(đ?œ†đ?œ†) 2: CIE (1924) Photopic V(Îť) 1 0.8 0.6 0.4 0.2 0 350
450
550
650
750
850
Wavelength (nm)
ď Ź
Relationship between energetic and luminous flux for a monochromatic or pseudo
= ÎŚ v K mV ( Îťd ) ÎŚ e . monochromatic source: ď Ź
Relationship between energetic and luminous flux for a polychromatic source: ď ˇ
ď ˇ
δ Ό′ ( Îť ) = lim  ÎŚ δ Îť →0 δ ďŁ Îť
  , where δΌ is the fraction of flux Ό contained in a spectral band of size 
đ?›żđ?›żđ?œ†đ?œ† about the wavelength Îť;
Ό′e = (Ν )
ÎŚe â‹… S ( Îť ) = ÎŁ
ÎŚe â‹… S ( Îť )
âˆŤ
∞
0
= ÎŁ normalized spectra;
1 2
S (Îť ) â‹… dÎť ∞
, where ÎŚđ?‘’đ?‘’ is the total energetic flux; S(Îť) is the
âˆŤ S (Îť ) â‹… dÎť 0
corresponding to the sum over the area of an
Optoelectronics of Molecules and Polymers, Moliton AndrĂŠ, Springer-Verlag New York, 2006. http://www.cvrl.org/lumindex.htm 1/5