New 1H-pyrazolo[3,4-b]quinoxaline derivatives as sharp green-emitting dopants for highly efficient electroluminescent devices

Abstract

Several new 1H-pyrazolo[3,4-b]quinoxaline derivatives with N,N-dialkylamino as the electron donating group were prepared; their photoluminescence in solution and electroluminescence have been investigated; they show emission at about 520–540 nm with a fluorescence quantum yield close to unity in solution; devices fabricated by using these compounds as dopants show green emission with efficiencies of 7.5–9.7 cd A⁻¹ and a narrow bandwidth of 65–70 nm peaking at 530–545 nm.