Development of Hole Transporting Layer-free Organic Photovoltaics

Abstract

Organic photovoltaics(OPVs) have emerged to attention as next-generation energy sources because of their high performance over 19% through the development of efficient organic photoactive materials. Therefore, technologies like streamlining the device manufacturing process are essential for commercialization. Over decades, poly(3,4-ethylenedioxythiophene):polystyrene sulfonate(PEDOT:PSS) has been the most commonly used hole transporting layer(HTL) for OPVs because of its high electrical conductivity and optical transparency. However, the low work function of PEDOT:PSS has led to a selectivity problem with photoactive materials. To address this issue, a work function tunable layer becomes imperative. Herein, we successfully modified PEDOT:PSS by blending perfluorosulfonic acid, which adjusts the work function to match the highest occupied molecular orbital(HOMO) of versatile donors for OPVs. Moreover, We fabricated hole transporting layer-free(HTL-free) OPVs by using the modified-PEDOT:PSS, serving both as the bottom electrode and HTL.