Temperature measurements of the PEDOT-PSS layer in a polymer light-emitting diode by stokes and anti-stokes Raman scattering

We have observed Stokes and anti-Stokes Raman scattering from an operating double-layer polymer light-emitting diode fabricated with poly(3,4-ethylenedioxythiophene)–poly(4-styrenesulfonate) (PEDOT–PSS) as a hole-injection layer (50 nm thickness) and a polyfluorene-based polymer blend as a light-emitting layer (90 nm thickness) with excitation at 633 nm. The temperature of the PEDOT–PSS layer was estimated to be 74 ± 6 °C at a current of 150 mA/cm2 (1000 cd/m2), whereas that of the glass surface measured by a thermocouple was 41 °C.