Drawing a polymer-based blue LED

Researchers in the group lead by Professor Michael Winokur at the University of Wisconsin have fabricated a polymer-based light-emitting diode (LED) using a Microplotter. The LED was a multilayer structure with the blue-emitting polymer poly[9,9-(di-n,n-octylfluorene)] (PF8) at its core. The other layers were made of an indium tin oxide electrode, a poly(ethyldioxythiophene) (PEDOT) layer to create a better electrical contact with the LED layer, poly(methylmethacrylate) (PMMA) as an insulator to mask off selected areas of the device, and a calcium top electrode covered with aluminum. The 100-300-nanometer-thick LED layer gave the device a turn-on voltage of 4 V.

Unique photoluminescence profiles were observed for PF8 films deposited by the Microplotter due to the unique nature of its line drawing at the microscale.