SOLUTION-PROCESSABLE REDUCED GRAPHENE OXIDE AS A NOVEL ALTERNATIVE TO PEDOT:PSS HOLE TRANSPORT LAYERS FOR HIGHLY EFFICIENT AND STABLE POLYMER SOLAR CELLS

摘要

The potential of a flexible, roll to roll manufacturing process has made bulk heterojunction (BHJ) organic solar cells (OSCs) very attractive as a promising solution to energy and environmental issues. In polymer solar cells, device characteristics as well as the cell lifetime all are highly dependent on the interface properties between the electrodes and the active layers and on the bulk properties of the materials. For these reasons, numerous modifications of electrodes by introduction of an interfacial layer have been studied intensively for high performance and stable OSCs. Among them, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) has been most commonly used as an anode interfacial layer (AIL) to improve anode contact and to increase hole collection in organic electronics. However, PEDOT:PSS has several problems including high acidity, hygroscopic properties, and inhomogeneous electrical properties, resulting in poor long term stability. To solve these problems, we have investigated solution processable graphene based thin films as anode interfacial layers for high performance and stable polymer solar cells. Here, GO, a conventional reduced graphene oxide (r-GO), and a newly reduced graphene oxide (pr-GO) by p-toluenesulfonyl hydrazide (p-TosNHNH2) were prepared and examined as novel AILs in solar cells.