**5.6 Way to increase the efficiency**

There are several ways to enhance the efficiency of OLED described below, Efficiency of OLEDs is reduced since the light emission of undoped systems is only accountable in single states. Recent advances in the collection of the triplets using phosphorescent materials have resulted in increased performance and color selectivity. To produce the primary colors required for display applications, the electric phosphorescence achieved by doping organic metallic phosphorus in a host was successfully used [46].

The doping of the emissive layer of an OLED has been widely used to improve performance, durability, and color. Tang et al., used fluorescent dyes, 3-(2-benzothiazolyl)-7-diethylaminocoumarine (coumarin 540), and DCMs were first developed dopant in Alq3 in 1989 to increase system effectiveness and color purity [47].

Endothermic energy transfer from a molecular organic host (donor) to organometallic phosphors (trap) can lead to high-efficiency electron lighting.

One of the most important factors restricting the external quantic power of devices is the low extraction of light and hence improved coupling methods for improved efficiency. In wave directed modes, almost 80% of the light provided by the OLED is lost in the radiation optics because of glass substrates and ITO/organism content, i.e. the majority of light produced is either stuck in or out of the edges of an OLED in the glass substratum or the system [48]. Various light refracting and dispersal approaches to reducing TIR at the interface have been identified to remove the trapped and wave-driven light into external modes, like using the shaped substitute, micro-lenses used on the backside of a substratum are used as a spreading medium and high-refractive-index substrate form the silica micro-sheet [49].

The other method is to inject a very low refractive index of silica aerogels between the glass substrates and the translucent ITO electrode.
