The invention belongs to the technical field of 
OLED, and provides a compound used as a 
host material. The compound has a structure as shown in a formula (I) which is described in the specification. In the formula (I), X is selected from the group consisting of C, O, S, Se, Si and Te atoms; a and b respectively represent the number of an 
electron donor D and an 
electron acceptor A and are respectively selected from the group consisting of 1, 2 and 3; c and d are respectively selected from the group consisting of 0, 1 and 2; L1, L2 and the 
electron donor D are respectively and independently selected from the group consisting of an 
alkyl group, a cycloalkyl group, a heterocyclic group, an 
aryl group, a heteroaryl group, a fused 
aryl group and a fused heteroaryl group; and the electrozxn 
acceptor A is selected from the group consisting of an azacycle-containing 
substituent, a cyano-containing 
substituent, a phosphoxy-containing 
substituent and a triaryl 
boron substituent. The compound provided by the invention has a D-(pi)-sigma-(pi)-A structure with bipolarity, and a sigma bond can effectively interrupt the intramolecular charge transfer between the 
electron donor D and the electronacceptor A, and limits an 
excited state to be a local 
excited state in a segment of D or A, so the compound has a 
dipole moment with a small 
excited state; and when the compound is used as the 
host material of a luminescent layer, the compound can effectively reduce the efficiency roll-off of a 
blue light material and improves luminescent brightness and luminescent efficiency.