Opto(electrical) properties of new aromatic polyazomethines with fluorene moieties in the main chain for polymeric photovoltaic devices

Abstract The opto(electrical) and photovoltaic properties of aromatic polyazomethines with fluorene moieties in the main chain were presented. 2,7-Diaminofluorene was polymerized in DMA solution with isophthaldicarboxaldehyde (F-13Iso), 2,5-thiophenedicarboxaldehyde (F-25Th) or 4,4′-diformyltriphenylamine (F-TPA). The temperatures of 5% weight loss ( T 5% ) of the polyazomethines range from 415 to 433 °C in nitrogen, depending on the dialdehyde used. Introduction of 1,3-phenylene moieties (F-13Iso) resulted in lower energy band gap ( E g opt. ) of approximately ∼0.43 eV, whereas F-25Th and F-TPA showed E g opt. of ∼2.46 eV. The conductivity of polyazomethines was approximately 10 −10 to 10 −9  S cm −1 at room temperature as determined by impedance spectroscopy. Electrical behavior of the two kind devices ITO/polymer:PCBM/Al and ITO/PEDOT:PSS/polymer:PCBM/Al were tested by impedance spectroscopy in dark and under illumination (halogen lamp, 100 mW cm −2 ). For all measured devices Nyquist plots were presented. The polymer solar cells devices were fabricated by spin coating the blend solution of the three polymers as donor and PCBM as acceptor. The devices comprised of polyazomethine F-25Th with PCBM (1:1) showed an open circuit voltage ( V OC ) of 0.36 V, a short circuit current ( J SC ) of 2.22 mA cm −2 , and a fill factor (FF) of 0.38, giving a power-conversion efficiency (PCE) of 0.31% under an illumination of 100 mW cm −2 with an AM1.5G.