Improved performance of solution processed OLEDs using N-annulated perylene diimide emitters with bulky side-chains

We have designed and synthesized three N-annulated perylene diimide (PDI) compounds containing sterically bulky alkyl-substituted benzyl moieties (PDI-X, where X = 1, 2, 3) with photoluminescence quantum yield (PLQY) in the solid-state >20%. The PDI molecules show PLQY of ∼0.8 in solution and ∼0.2 as neat films. Organic light-emitting diodes (OLEDs) have been fabricated using these new PDI molecules as light emitters with the active layer being solution processed from non-halogenated solvents. The OLED devices had brightness of ∼2000 cd m−2 and low turn-on voltage of ∼3 V, among the best for PDI based red colored OLEDs.