Organic light emitting diodes (OLEDs) have gained tremendous attention in the display and lighting technologies due to their attractive features such as: 1) color reproducibility due to wider color gamut, 2) thin and light weight, 3) ease of fabrication, 4) power efficient and 5) applicability on flexible applications. Obtaining a high efficiency pure blue emitting OLED suitable for display application is still challenging due to the reliability issues present in phosphorescent and thermally activated delayed fluorescent (TADF) emitters. In this work, we present an optimized device structure of a host-guest matrix based pure blue fluorescent OLED with a Commission Internationale de l’Eclairage (CIE) coordinate of (0.148,0.091) using BSB4 as the fluorescent emitter. A pure blue emission suitable for display application is achieved by the blue shift of the emission spectrum of the host-guest matrix from that of the pristine guest molecules. The optimization of OLED structure is carried out by considering (i) charge balance in the emissive layer for high exciton density, and (ii) optical interference of generated light in the organic layers for increased light outcoupling. Optical interference effects in the fabricated OLEDs are analyzed by optical simulation of each device structure by transfer matrix method (TMM). To improve the electron injection efficiency for better charge balance, we study the influence of Bathophenanthroline (BPhen) and LiF with optimized thicknesses as electron transport layer (ETL) and electron injection layer (EIL) respectively. The optimized device yields an external quantum efficiency (EQE) of 3.12% at 1000 cd/m2 with a very low roll-off of 3.1% from the maximum EQE of 3.22% at 300 cd/m2. The EQE achieved is significantly higher than the existing reports of blue OLED with BSB4 as a light-emitting material even at high brightness operations.