High-efficiency polymer light-emitting diodes(PLEDs) have been realized based on thermally cross-linking NPD dimer as hole-injecting layer on the top of PEDOT by spin-coating.The device structure used here is ITO/PEDOT(40 nm)/VB-NPD/PFBT5(40 nm)/TPBI(20 nm)/CsF(1 nm)/Al(100 nm).At the optimal thichkness of VB-NPD=20 nm,the maximal luminance efficiency of 15.0 cd/A and the maximal luminance of 32 200 cd/m2 are achieved.The improved device performance is attributed to the effective electron blocki...