Raman temperature measurements of copper phthalocyanine layer of organic light-emitting diode using bandwidth-temperature relationship

We have estimated the temperature of a buried copper phthalocyanine (CuPc) layer in an organic light-emitting diode with the glass/indium-tinoxide (ITO)/CuPc/N,N0-di-1-naphthaleyl-N,N0-diphenyl-1,10-biphenyl-4,40-diamine (NPD)/tris(8-quinolinolato)aluminum(III) (Alq3)/LiF-Al structure from the full width at half-maximum (FWHM) of a Raman band at around 1528 cm-1. The FWHMs of the band were measured at temperatures in the range from 25 to 200 C. A linear equation was obtained from the observed data by the least-squares method. We estimated the temperature of the CuPc layer in an operating organic light-emitting diode at current densities from 100 to 1000 mA/cm2 using this relationship. The highest temperature was 148 4 -C at a current density of 1000 mA/cm2.