Hole transport triphenylamine-spirosilabifluorene alternating copolymer: synthesis and optical, electrochemical and electroluminescent properties

A new copolymer, constituted by the regular alternation of a spirosilabifluorene with a triphenylamine moiety, P(TPA-SSBF), has been synthesized via Suzuki coupling reaction. The molecular, thermal, optical, electrochemical and electroluminescent properties have been characterized. The introduction of a spiro-structure in P(TPA-SSBF) leads to its high thermal stability and good solubility in common organic solvents. The alternating copolymer shows only an absorption peak of 342 nm, demonstrating that triphenylamine is significantly conjugated with fluorene rings in the polymer. P(TPA-SSBF) in chloroform solution and in solid state film exhibits blue emission peak at 423, 435 nm respectively. The electrochemical behaviors of the polymer were investigated by cyclic voltammetry. The reversible electrochemical oxidation and low ionization potential (5.47 eV) suggest that P(TPA-SSBF) might have potential application as hole transport material in polymer LEDs. The hole transport ability of P(TPA-SSBF) was verified by comparing the performance of the two types LED devices fabricated in this study.