The invention belongs to the technical field of OLEDs (organic light emitting diodes) and provides a
polymer of a structure of formula (I) as shown in the specification. In the formula, R1 and R2 arerespectively selected from C1-C20
alkyl, C3-C20 naphthenic base, C1-C20 alkoxyl and substituted or unsubstituted
aryl or heteroaryl; L is selected from single bonds, phenyl, naphthyl, pyridyl, pyrimidyl and pyrazinyl; R3 is selected from substituted or unsubstituted
aryl or heteroaryl; R4 is selected from
alkyl or alkoxyl of C4-C20; n is greater than or equal to 4. The
polymer provided by the invention comprises heterocyclic
boron-
carbazole structure and has TADF (thermal activation
delay fluorescence) properties, when the
polymer is used in an organic
light emitting diode, light can be emitted from
triplet exciton with transition inhibition of conventional
fluorescence molecules, and thus the efficiency of a device can be improved. Meanwhile, a
carbazole polymer type TADF material self has a bipolar property, when the polymer is used as a main body or secondary material of a light emitting layer, the transmission capability of two charge carriers and
charge carrier balance can be greatly improved, the
fluorescence quantum efficiency can be improved, and the
voltage of the device can be reduced.