Thickness of emissive layer in organic electroluminescent device is one of the important factors affecting the device performance. In this report, a blue electroluminescent device with an active layer of 4, 4＇-bis（2, 2＇-diphenylvinyl） -1, 1＇- biphenyl （DPVBi） is fabricated. The device performance varies with the thickness of DPVBi. With the increase of the DPVBi thickness between 10-50 nm, the device luminance and efficiency at the same current density first increase and then decrease, the device with a DPVBi thickness of 40 nm exhibits the highest luminance of 15840 cd/m^2 and a maximum external quantum efficiency of 3.2%, with Commission Internationale de 1＇Eclairage （CIE） co-ordinates being （0.15, 0.15）. The luminescent spectral red shift and the color purity deteriorate when the thickness is over 40 nm, which can be attributed to a result of microcavity effect. In the meantime, the analysis from experimental results shows that the exciton diffusion length in DPVBi is between 20---30 nm%本文制备了联苯乙烯衍生物（4,4＇-bis（2,2＇-diphenylvinyl）-l,l＇-biphenyl,DPVBi）为发光层的蓝色有机电致发光器件.器件性能随发光层厚度变化而变.在DPVBi厚度为10—50 nm范围内,同样电流密度下器件亮度及效率随DPVBi厚度增加先增后减,40 nm时最佳,最高亮度达到15840 cd/m~2,最高外量子效率达到3.2%,器件色坐标（Commission Internationale de l＇Eclairage（CIE）co-ordinates）为（0.15,0.15）.DPVBi厚度超过40 nm时器件发光光谱出现红移而致色度变差,其原因可归于微腔效应所致.同时,通过实验结果分析表明DPVBi中激子扩散长度位于20—30 nm范围.
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