Sn(SCN)2 as an additive for improving the hole transport properties of PEDOT:PSS in organic photovoltaics

Abstract

Tin(II) thiocyanate [Sn(SCN)₂] has been recently demonstrated as an anode interlayer and additive in the electron transport layer (ETL) for organic photovoltaics (OPVs). We further demonstrate herein the application of this emerging electronic material as an additive for poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS), employed as a hole transport layer (HTL) in OPVs. Sn(SCN)₂ is processable using common solvents; the addition of a small amount of Sn(SCN)₂ leads to some removal of PSS and dedopes PEDOT. Despite the lower conductivity, the simple process effectively enhances the hole transport properties and overall device performance. The optimal additive concentration yields an increase in the average power conversion efficiency (PCE) from 9.0% (pristine) to 9.8% [Sn(SCN)₂-added] for OPVs based on a well-known bulk-heterojunction layer.