Synthesis and Electro-Optical Properties of a New Conjugated Polymer Based on a Tetrazine Moiety for Solution-Processed Devices

A new electrical small molecule and polymers with electron-withdrawing effects stemming from a tetrazine moiety were synthesized. The electro-optical properties of 3-([1,1’-biphenyl]-3-yl)-6-(4-(tert-butyl)phenyl)-1,2,4,5-tetrazine (TB-TTZ-DP), poly(9-ethyl-3-(4-(6-phenyl-1,2,4,5-tetrazin-3-yl)phenyl)-9H-carbazole) (ECBZ-TTZ), and poly(9-(henicosan-11-yl)-3-(3-(6-phenyl-1,2,4,5-tetrazin-3-yl)phenyl)-9H-carbazole) (DCBZ-TTZ) were compared. TB-TTZ-DP, ECBZ-TTZ, and DCBZ-TTZ in the solution state exhibited maximum absorption wavelengths of 309, 312, and 321 nm, respectively; in the film state, they exhibited maximum absorption wavelengths of 308, 341, and 302 nm, respectively. These results correspond to bandgaps of 3.63, 3.10, and 3.54 eV, respectively. The ECBZ-TTZ and DCBZ-TTZ polymers exhibited maximum PL wavelengths of not only 411, 474, and 407 nm in the solution state but also 412 and 476 nm (ECBZ-TTZ) and 371 and 416 nm (DCBZ-TTZ) in the film state. The electrochemical properties of the three materials were tested in the potential range from -0.5 to 1.5 V and all three materials demonstrated stable redox properties. The exponent of the scan rate ( i.e. , the x -value) for TB-TTZ-DP, ECBZ-TTZ, and DCBZ-TTZ was 0.61, 0.64, and 0.77, respectively. The kinetics of the redox process were controlled by combination of diffusion and electron transfer processes. Among organic light-emitting diodes fabricated using the three materials, the device with DCBZ-TTZ exhibited the best current-voltage characteristics.