Solution processable graphene derivative used in a bilayer anode with conductive PEDOT:PSS on the non-fullerene PBDB-T:ITIC based organic solar cells

Abstract

In this work, a semi-transparent, low-cost and easy processable graphene derivative and PH1000 (conductive PEDOT:PSS polymer) based bilayer anode, is presented as a sustainable potential alternative to ITO. The simple mechanical-synthesized graphene derivative was in aqueous-suspension processed (SPG) and drop-coated onto a common glass substrates. The SPG film presents a Raman intensity ratio (ID/IG) of 0.56 and a number of 7 sheets theoretically estimated. Modified PH1000 with dimethyl sulfoxide (DMSO) was spin-coated onto SPG layer. The bilayer anode (SPG/PH1000) exhibits a transmittance, roughness and resistance of 82% (550 nm), 9 nm and 226 Ω/sq, respectively. The bilayer alternative electrode is used in the manufacture of organic solar cells (OSCs) based on the non-fullerene PBDB-T:ITIC active layer. Average power conversion efficiency (PCE) of 8.3% (best 8.6%) is attained for control devices (using ITO as anode) and 4.0% (best 4.2%) for devices with the alternative SPG/PH1000 bilayer anode. For OSCs fabrication, a vacuum free deposited top electrode Field’s metal (FM, an eutectic alloy of Bi 32.5%, In 51% and Sn 16.5%, with a melting point above 62°C) was used.