Synthesis And Optical-electrical Properties Of Phenothiazine Based Polymers

Polymer light emitting devices have been a fascinating subject owing to its potential application in large-scale flat displays. In order to have better performance, it is essential to develop novel structural polymeric materials with balanced transport of both injected electrons and holes. By changing or modifying the structures of organic semiconductor materials can easily adjust the energy level and charge transporation. Phenothiazine is a well -known heterocyclic compound with electron-rich nitrogen and sulfur heteroatoms.Conjugated polymers and copolymers based on phenothiazine have been investigated. It has been demonstrated that phenothiazine unit is an excellent p-type building block for lowering ionic potential of conjugated polymers due to its readily injection and transport of hole and non-planarity of phenothiazine impedesπ-stacking aggregation and intermolecular excimer formation which maybe lead to the poor quantum efficiency.Three novel phenothiazine-based monomers (M1,M2,M3) were designed and synthesized.Their physical and chemical properties were characterized by UV-vis and PL The results reveal that conversion of electron-donating sulfur in phenothiazine molecular to electron-withdrawing phenothiazine-5-oxide can enforce theπ-π* transition.However, the conversion of phenothiazine-5-oxide in phenothiazine molecule to phenothiazine destroy theπ-π* transition.Three polymers containing phenothiazine, phenothiazine-5-oxide and phenothiazine -5,5-oxide units were prepared by Wittig reaction. The photo-physical and electroluminescent properties of resulting polymers were investigated.Single layer device with a structure of ITO/ polymer /Ca/Al and double layer devices with a structure of ITO/polymer/Zn(BTZ)2/Ca/Al were built up. The brightness of double layer devices for P1,P2 and P3 is 277.6 cd/m2, 400.7 cd/m2 and 796.3 cd/m2, respectively.Two novel copolymers composed of fluorene and phenothiazine derivates are synthesized.The photo-physical, electroluminescent and electrochemical properties of two polymers were characterized by UV-Vis, PL, EL and Cyclic Voltammetry (CV). Single layer structure devices with the configuration of ITO/Polymers/Ca/Al were fabricated. The CV results demonstrated that introduction of phenothiazine moiety into polyfluorenes can enhance electron affinity (EA) and lower the ionic potential (Ip). EL results revealed that all these two copolymers emit green light with the maximum brightness of 20 cd/m2(16 V)and 12.5 cd/m~2(15 V),respectively.Copolymers of thiophene-co-phenothiazine were prepared by Wittig reaction. The synthesis, photo-physical and electroluminescent properties of the resulting polymers were analyzed by FT-IR, GPC, 1H-NMR, UV-Vis, Photoluminescence (PL), Electroluminescence (EL) and Cyclic Voltammetry (CV). The single layer devices with configuration of ITO/polymers/Ca/Al were studied. The device with a single layer structure of ITO/Polymer/Ca/Al emit red light with the maximum brightness of 50 cd/m2(17V).