This article investigates the problem of light extraction from LED devices fabricated via chip-on-board technology and emitting in ultraviolet (UV) range (360-380 nm) of spectrum. The measurements of electrical and optical properties of devices with varying number and arrangement of semiconductor chips were conducted. Optimization modeling was performed with Zemax software. Modeling included the choice of substrate material, variation in the chip arrangement, and the change in the properties of the covering layer. All together, the accomplished study allowed us to elaborate the recommendations for improving the performance of UV LED devices. In particular, it was demonstrated that the optimization of chip arrangement on the substrate can provide 10 % increase in energy efficiency of LED modules.