Planar polymer light-emitting electrochemical cells with extremely large interelectrode spacing

Planar polymer light-emitting electrochemical cells have been demonstrated with interelectrode spacings nearly 100 times larger than previously reported. Striking details of the p-i-n junction structure have been imaged directly using a digital camera. With an interelectrode spacing of 1.5 mm, a well-defined emission zone over 70 mum wide is observed near the cathode. Imaging under UV excitation reveals that the p-doped region migrates towards the cathode during operation, causing the emission zone at its frontier to shift. The width of the p-doped region is found to have a large variance, giving rise to an irregularly shaped emission zone. (C) 2003 American Institute of Physics.