Light-emitting field-effect transistors (LEFET) based on poly [2-methoxy-5-(2-ethylhexoxy)-1,4-phenylenevinylene] (MEH-PPV) were prepared with asymmetric electrodes of a Au/Cr source and an Al drain on a SiO2 gate insulator (600nm) through twice of photolithography and lift-off techniques. The light emission was observed when the gate voltages increased above -40V at the drain voltage of -100V. The luminous efficiency of the devices was significantly improved comparing to those with conventional electrodes of Au/Cr.