Photoluminescence and electroluminescence in Langmuir–Blodgett films of poly(3-decylmethoxythiophene)

The photoluminescence (PL) and electroluminescence (EL) of poly(3-decylmethoxythiophene) have been studied for devices fabricated using both the spin-coating, and Langmuir–Blodgett (LB) technique. Strong thermochromic effects in the PL, correlated to a thermal transition in the polymer, are observed for the spin-coated films while negligible thermal dependence of the PL is observed in the LB films. A blue shift of the EL with respect to PL is observed for the LB films and is associated to partial polymer degradation. By analysing the time evolution of EL during the first minutes of device operation, the processes related to annealing and Al diffusion at the electrode/polymer interface are discussed.