Versatile Direct Cyclization Constructs Spiro-acridan Derivatives for Highly Efficient TADF emitters.

Spiro-acridan (SpA) derivatives possess a great potential in preparing efficient thermally activated delayed fluorescent (TADF) emitters. However, the conventional synthetic routes are cost-expensive and time-consuming. The development of a simple procedure to synthesize SpAs is still in urgent pursuing appreciated by academic and industrial communities. In this contribution, we present a feasible acid-catalyzed solvent-free metal-free cyclization between diarylamines and ketones to construct SpAs. The as-constructed moieties provide a wide possibility to assemble efficient TADF emitters. As an example, D2T-TR with high photoluminescent quantum yield and proper TADF character is applied in organic light emitting diodes (OLEDs) which achieves a maximum external quantum efficiency (EQE) of 27.1 %. This work shows us a bright inspiration on developing excellent organic optoelectronic materials and an effective tool to realize it.