Synthesis and Characterization of Thermally Cross-linkable Hole Transporting Material Based on Poly(p-phenylenevinylene) Derivative

열경화가 가능한 poly(p-phenylenevinylene)계 정공전달 물질의 합성 및 특성

  • Choi, Jiyoung (Division of Applied Chemical Engineering, Department of Polymer Engineering, Pukyong National University) ;
  • Lee, Bong (Division of Applied Chemical Engineering, Department of Polymer Engineering, Pukyong National University) ;
  • Kim, Joo Hyun (Division of Applied Chemical Engineering, Department of Polymer Engineering, Pukyong National University)
  • 최지영 (부경대학교 공과대학 응용화학공학부 고분자공학과) ;
  • 이봉 (부경대학교 공과대학 응용화학공학부 고분자공학과) ;
  • 김주현 (부경대학교 공과대학 응용화학공학부 고분자공학과)
  • Received : 2008.02.12
  • Accepted : 2008.03.26
  • Published : 2008.06.10

Abstract

A thermally cross-linkable polymer, poly[(2,5-dimethoxy-1,4-phenylenevinylene)-alt-(1,4-phenylenevinylene)] (Cross-PPV), was synthesized by the Heck coupling reaction. In order for the polymer to be cross-linkable, 20 mol% excess divinylbenzene was added. The chemical structure of Cross-PPV and thermally crosslinked Cross-PPV were confirmed by FT-IR spectroscopy. From the FT-IR, UV-Vis, and PL spectral data, thermally crosslinked Cross-PPV was insoluble in common organic solvents. The HOMO and LUMO energy level of thermally cross-linked Cross-PPV were estimated -5.11 and -2.56 eV, respectively, which were determined by the cyclic voltammetry and UV-Vis spectroscopy. From the energy level data, one can easily notice that thermally crosslinked Cross-PPV can be used for hole injection layer effectively. Bilayer structured device (ITO/crosslinked Cross-PPV/PM-PPV/Al) was fabricated using poly(1,4-phenylenevinylene-(4-dicyanomethylene-4H-pyran)-2,6-vinylene-1,4-phenylenevinylene-2,5-bis(dodecyloxy)-1,4-phenylenevinylene (PM-PPV) as the emitting layer, which have HOMO and LUMO energy levels of -5.44 eV and -3.48 eV, respectively. The bilayered device had much enhanced the maximum efficiency (0.024 cd/A) and luminescence ($45cd/m^2$) than those of a single layer device (ITO/PM-PPV/Al, 0.003 cd/A, $3cd/m^2$). The enhanced performance originated from that fact that cross-linked Cross-PPV facilitatse the hole injection to the emissive layer and the injected hole and electron from ITO and Al are recombined in emitting layer (PM-PPV) effectively.

Acknowledgement

Supported by : 부경대학교

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