In-situ modification of PEDOT:PSS work function using alkyl alcohols as secondary processing solvents and their impact on merocyanine based bulk heterojunction solar cells

The influence of a series of alkyl alcohols on the work function of PEDOT:PSS thin films is systematically investigated by Kelvin probe measurements. We show that the PEDOT: PSS work function can be increased stepwise from 5.2 eV for pristine PEDOT: PSS to 5.61 eV using either alcohols with different alkyl chain length or varying the amount of alcohol in mixtures with chlorobenzene. Moreover, we demonstrate the effect of work function modification on merocyanine based bulk heterojunction solar cells, resulting in improved values for the open-circuit voltage comparable to those obtained with high work function MoO3. Thus, the processing method presented herein can potentially serve as a simple, alternative route to adjustable and high work function electrodes while maintaining processability from solution. (C) 2015 Elsevier B.V. All rights reserved.