Novel Film-Casting Method for High-Performance Flexible Polymer Electrodes

Abstract

A new fi lm-casting method for polymer electrodes is reported, in which thickness-controlled drop-casting (TCDC), using polyaniline doped with camphorsulfonic acid (PANI:CSA) is used. By combining the advantages of conventional spin-casting and drop-casting methods, and by rigorously controlling the fi lm formation parameters, fl exible polymer electrodes with high conductivity and excellent transmittance can be produced. The PANI:CSA electrodes cast by the TCDC method exhibited constant thickness-independent conductivities of ∼ 600 S cm − 1 down to a fi lm thickness of 0.2 μ m, and a high optical transmittance of about 85% at 550 nm. Furthermore, the new casting method signifi cantly reduced the sheet resistance ( ∼ 90 Ω /square) of the PANI:CSA electrodes compared with the conventional spin-cast fi lms, enhancing the performance of the devices deposited on plastic substrates. The fl exible polymer light-emitting diode produced a brightness of 6000 cd m − 2 , and the fl exible polymer solar cell exhibited a power conversion effi ciency of 2%, both of which were much higher than those of the devices fabricated by the conventional spin-casting method.