Synthesis and photovoltaic characterization of D/A structure compound based on N-substituted phenothiazine and benzothiadiazole

In this study, poly [(N-10′-dodecyl-phenothizin-3,7-ylene)-alt-(2,2′-bithiophen-5-yl)] (P1) and poly [(N-10′-dodecyl-phenothiazin-3,7-ylene)-alt-(5′,6′-dioctyloxy-benzothiadiazole-bithiophene)] (P2) were synthesized by Suzuki coupling reaction. Optical and electrochemical characteristics of the synthesized polymers, P1 and P2, were then analyzed, indicating that their wavelength of maximum absorption was 453 nm and 533 nm, respectively, and their band-gap was 1.93 eV and 1.74 eV, respectively. The maximum power conversion efficiency (PCE) of organic photovoltaic cells created by using P1 and P2 were 0.74% (P1:PC71BM = 1:4,w/w) and 1.00% (P2:PC71BM = 1:3,w/w), respectively, and the short circuit current density (JSC), fill factor (FF), and open circuit voltage (VOC) of the device were 3.5 mA/cm2, 31.8%, and 0.68 V, respectively, for P1 and 3.9 mA/cm2, 32.7%, and 0.78 V, respectively, for P2.