White multi-layered polymer light emitting diode by Matrix Assisted Pulsed Laser Evaporation

The development of alternative deposition techniques of conjugated polymeric compounds is an important step towards the fabrication of low cost multi-layered organic light emitting diodes suitable for display or lighting applications. In this work we show a white light -emitting polymeric hetero-structured diode consisting of three-stacked blue, red and green light emitting polymers. In order to circumvent the issue of selecting orthogonal solvents in solution -deposition approaches, we combine spin-coating with the Matrix Assisted Pulsed Laser Evaporation technique, resulting in the realization of a polymeric multilayered stack. By controlling the carriers and the energy transfer across the three light emitting layers interfaces, as well as the interplay between the deposition parameters, a pure white colour emission with Commission Internationale de l'Éclairage coordinates (X=0.327, Y=0.374) and a Color Rendering Index of 70 have been achieved. Our study represents the first proof of a light emitting diode made by multilayer polymeric thin films emitting white light.