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

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.