Metal oxide-free flexible organic solar cells with 0.1 M perchloric acid sprayed polymeric anodes

Future flexible organic solar cells (OSCs) require high efficiency, good flexibility and low fabrication cost. Here, we demonstrate a metal oxide-free flexible OSC based on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) anodes with a small amount of perchloric acid (HClO4) spray doping. The optimized flexible OSCs yield a mean efficiency of 16.44%, which is the highest value for metal oxide-free flexible OSCs reported so far. The high efficiency is ascribed to the HClO4 spray doping that pulls the anode's Fermi level down, decreases the sheet resistances, and induces an intimate contact at interfaces. The spray doping also avoids direct contact between HClO4 and plastic substrates, and thus the devices maintain good flexibility. This work clearly demonstrates the advantage of the unique HClO4 spray doping method over the well-known strong acid soaking method and complicated transfer-printing strategies for application in anodes of flexible OSCs. This journal is