The effect of intermediate layers on the internal electric field in organic semiconductor devices (original) (raw)

In this work we study the internal electric field (V int) present in devices based on an intrinsically semiconducting polymer. Intermediate layers between the indium-tin-oxide and Al electrodes and the photoactive layer are able to influence and alter this electric field. The two commonly used intermediate layers, namely poly(3,4ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT:PSS) and LiF, are subject of this study. Their influence is studied with Electroabsorption (EA) spectroscopy as well as transient photocurrent measurements under applied bias. While PEDOT:PSS has no significant influence on V int , introducing LiF increases V int close to the bandgap of the studied semiconducting polymer. However, using PEDOT:PSS directly influences the spectral EA response. The interface between PEDOT:PSS and the conjugated polymer is studied by impedance spectroscopy. We interpret the results in terms of the presence of charges at the interface.