Efficient white light emission in conjugated polymer homojunctions

We study polymer light-emitting diodes with a homojunction, i.e., junction between two layers with the same host material. One layer is poly (9,9-dioctylfluorene-2,7-diyl) (PFO) host blended with a small amount of poly (2-methoxy-5 (2'-ethyl-hexyloxy)-1,4-phenylene vinylene), another layer is either pure PFO or PFO host blended with green-emitting polyfluorene copolymers. Such homojunction devices are solution processed and show efficient white light emission. The peak luminance $3000\mathrm{cd}∕{\mathrm{m}}^2$ is reached at $10\mathrm{V}$ with Internationale de L’Eclairage (CIE) coordinate (0.34, 0.34).