Solution-processed high-performance orange phosphorescent and white PLEDs with a high color-rendering index from an unprecedented π-stacked and π-conjugated host material

A blue fluorescent polymer based on poly(vinyl carbazole) (PVK) and terfluorene, combined to make a chemical hybrid at the carbazole unit (PVK-TF), is fully characterized in this study. PVK-TF shows useful emission features, such as peaks at 400, 420, 437, 460, and 496 nm, depending on the processing conditions. It possesses a relatively high triplet energy level (2.23 eV), electrochemical stability, good film-forming ability, and morphological stability. Based on this blue fluorescent material, highly efficient orange phosphorescent polymer light-emitting diodes (PLEDs) were fabricated with a maximum efficiency of 21.99 cd A^-1, and a maximum luminance of 19552.3 cd m^-2. Single-layer hybrid white PLEDs were developed, with a high color rendering index of 81.9 that emitted across the whole visible spectrum from 380 to 780 nm, corresponding to the Commission International de L'Eclairage coordinates x, y values of around (0.38, 0.40) and CCT = 3774, with a maximum current efficiency of 10.69 cd A^-1, and a maximum brightness of 15723.3 cd m^-2.