New carbazole-substituted anthracene derivatives based non-doped blue light-emitting devices with high brightness and efficiency

• A series of anthracene derivatives featuring carbazole moieties as side groups were synthesized for use in blue OLEDs.
• Efficient conjugation resulted in high PL efficiencies of anthracene derivatives in solution.
• High brightness and great current efficiency were observed for the anthracene derivatives based OLEDs.

A series of anthracene and 2-tert-butyl–substituted anthracene derivatives featuring 9-ethyl-9H-carbazol-3-yl or 4-(9-ethyl-9H-carbazol-3-yl)phenyl groups were synthesized for use as light-emitting layer in sky-blue organic light emitting devices (OLEDs). Efficient conjugation between the carbazole and anthracene unit resulted in strong blue emissions and high quantum efficiencies of anthracene derivatives in solution. Electroluminescence (EL) properties of non-doped OLEDs incorporated with these anthracene derivatives, along with an electron-transporting layer (ETL), tri-(8-hydroxyquinoline)aluminum (Alq3) or 1,3,5-tris(N-phenyl benzimidizol-2-yl)benzene (TPBI) were investigated. The OLEDs incorporated with TPBI provided superior EL performance than did those incorporated with Alq3. A hole-blocking layer 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) was inserted at the interface of light emitting layer and ETL to enhance the EL performance for the OLED with Alq3 as ETL. High brightness (37423 cd/m2), and great current efficiency (5.89 cd/A) were observed for the 4-(9-ethyl-9H-carbazol-3-yl)phenyl-substituted anthracene derivatives based OLEDs.

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