| 초록 |
Tin-based alternating copolymers with a uniform π-conjugated segment were synthesized using the Heck reaction between distyrylstannane monomer and various difunctionalized monomers. The UV-visible absorption spectra of the resulting polymers in chloroform solution and in thin films appeared in the wavelength range of 350 ∼ 394 nm. Upon photoexcitation with light of wavelength 350 nm, their photoluminescence spectra exhibited an emissive peak around 470 ∼ 502 nm, corresponding to blue light emission. Multi-layered light-emitting diodes with ITO/PEDOT (50nm)/Polymer (80nm)/Ca (50nm)/Al (200nm) composition were fabricated. These LED devices exhibited an emissive peak in the range of 464 ∼ 472 nm. All of the materials exhibited an extremely low turn-on voltage of less than 4 V, as determined from plot of current density versus applied voltage. Compared to devices based on the tin-based polymers alone, devices based on blends between the tin-based polymers and PVK showed improved efficiency of power and luminescence by at least 2 ∼ 4 times and 3 ∼ 6 times, respectively. Also for these polymer:PVK blends, the electroluminescence efficiency enhances up to the range of 0.1 ∼ 0.3 lm/W and the purity of the emitted blue color improves. One of the devices based on a blend system between a tin-based polymer and PVK has a brightness of 2047 cd/m2 at 11 V with a power efficiency of 0.3 cd/A. |
