Polyalkylthiophene-containing electron donor and acceptor heteroaromatic bicycles: synthesis, photo-physical, and electroluminescent properties

摘要

The synthesis and characterization of a series of polyalkylthiophenes-containing electron-rich thienothiophene (donor heteroaromatic bicycle) and electron-deficient benzothiadiazole (acceptor heteroaromatic bicycle) block have been reported. The polymers are synthesized by Stille cross-coupling reaction and are found to be having high molecular weight with number-average molecular weight in the range of 7.1 9 10~4-5.7 9 10~4. The photo-physical, electro-chemical, and electroluminescent (EL) properties of the polymers are investigated in detail.The optical band gap of the polymers is found to be in the range of 1.53-1.54 eV. These newpolymers are luminescent in nature and showed red photoluminescence in chloroform solution (722-740 nm) as well as in thin film (781-786 nm). Ionization potential for these polymers is calculated and falling in the range of 5.23-5.33 eV. Polymer light emitting diodes with configuration ITO/PDOT:PSS/polymer/BCP/Alq_3/LiF/Al have been fabricated, and a deep red emission is observed. The EL maxima of polymers are found to be in the range of 750-760 nm with threshold voltages around 4.0-5.5 V. The fabricated devices show luminescence around 40 cd/m2 at current density of 100 mA/cm~2 with maximum value of 580-810 cd/m~2 at 11 V.