Novel ternary exciplex system based on TCTA dendrimer with a new linking type amongst various functional donors

A novel electron-rich dendrimer 4,4′,4″-(9,9′-(5-((6-(9H-carbazol-4-yl)hexyl)oxy)-1,3-phenylene)bis(9H-carbazole)-9-yl)-tris(N,N-bis(4-(9H-carbazol-9-yl)phenyl)aniline)(TCTA-O-MCP) containing conventional hole-transporting material 4,4,4″-tris(N-carbazolyI)-triphenylamine (TCTA) and 1,3-Bis(N-carbazolyl)benzene (MCP) is designed and mixed with electron-transporting materials 1,3,5-Tris(N-phenylbenzimidazol-2-yl)benzene (TPBI) to form ternary exciplex system. When TCTA-O-MCP and TPBI are mixed physically, the exciplex display 440 nm blue emission. In addition, The TCTA-O-MCP:TPBI exciplex system exhibited a small singlet–triplet splitting energy (ΔE_ST) of 0.07 eV, resulting in an efficient reverse intersystem crossing process (RISC) with a longer lifetime (0.43 µs) and unique thermally activated delayed fluorescence (TADF) characteristics. The exciplex can significantly weaken the electromer emission compared to the TCTA:TPBI and MCP:TPBI exciplex systems. The strategy of using dendrimer may provide inspiration for the molecular design in controlling the electromer emission.