**3. Conclusions**

*Microwave Heating - Electromagnetic Fields Causing Thermal and Non-Thermal Effects*

the LEDs in which the light-emissive electroluminescent film is made up of organic molecules. In the case of *O*-LEDs the highest occupied molecular orbital (HOMO) is the conduction band, and the lowest unoccupied molecular orbital (LUMO) is the empty valence band of organic substance. *O*-LEDs are preferred over LEDs due to the facts that an *O*-LED is thinner and have a better display property; it has brighter, fast responsive, and long-range contrast display. Moreover, *O*-LEDs have wider viewing angles with low driving voltage property. *O*-LEDs can be conveniently fabricated on a glass surface at low temperatures. Organic semiconducting materials are in the crystalline or polymeric phase. Organometallic compounds, polymers, and even simple organic molecules like aryl amines are used in *O*-LEDs. The research in the field of *O*-LEDs is in rapid progress as these displays are already in use in modern electronic and optoelectronic appliances like heads-up displays, billboard-type displays,

automotive dashboards, home and office lighting, and flexible displays. The synthetic invention of these organic moieties is a progressive field, and the microwave-assisted synthetic methods of *O*-LEDs have also started sprouting in recent years [60, 61]. The amalgamation of organic moieties and inorganic matrices results in the synergetic effects by augmenting of the properties like flexibility and shape ability with stability [62]. Poly (2-hydroxyethyl methacrylate) (PHEMA) silica-hybrids have been prepared by microwave irradiation [63]. Organoboron dye diketonate BF2 complex **77**, borondipyrromethene (BODIPY) **78**, and (1,3-boron di(iso)indometh-

N,N-Diphenylamine (DPA) were transformed to form precursors for *O*-LEDs using solid state microwave-assisted organic synthetic method [64]. This reaction was carried out in the MAS II SINEO microwave reactor in presence of Iodine and alumina. The temperature range of 125–133°C was optimized and the reaction was completed in 15 minutes at 500–600 W power of the reactor. After typical work up procedure they ended up with two fractional mixtures of compounds **80** to **85** with

ene dye **79** can be integrated into these PHEMA silica hybrids.

fluorescence property were obtained.

**72**

Since from the centuries, dyes have played a very important role in human life. The functional dyes have changed the technologies drastically and have gained immense importance now a day. A specific property of the dye depends on the various factors such as the donor, electron acceptor/π-conjugation, linker, etc. present at appropriate positions. More effort has been established into searching for better dyes with expected properties. Microwave-assisted synthesis has changed the methodology of organic synthesis and hence is also efficiently applied in the synthesis of functional dyes. Therefore, a number of dyes synthesized under microwaves along with their applications were discussed. There is a possibility for further development in organic synthetic methodology under microwaves to obtain dyes having wider applications in organic photovoltaics, fluorescence sensors, photochromic materials, OLEDs, etc.
