title: Graphene oxide/PEDOT:PSS composite hole transport layer for efficient and stable planar heterojunction perovskite solar cells.
abstract: We investigated a graphene oxide (GO)/poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (
  PSS) composite as a promising candidate for the practical application of a 2-D carbonaceous hole transport layer (HTL) to planar heterojunction perovskite solar cells (PeSCs) consisting of a transparent electrode/HTL/perovskite/fullerene/metal electrode. Both the insulating properties of GO and the non-uniform coating of the transparent electrode with GO cause the poor morphology of perovskite induced low power conversion efficiency (PCE) of 6.4%. On the other hand, PeSCs with a GO/PEDOT:PSS composite HTL, exhibited a higher PCE of 9.7% than that of a device fabricated with conventional
  PSS showing a PCE of 8.2%. The higher performance is attributed to the decreased series resistance (RS) and increased shunt resistance (RSh). The well-matched work-function between GO (4.9 eV) and
  PSS (5.1 eV) probably results in more efficient charge transport and an overall decrease in RS. The existence of GO with a large bandgap of ∼3.6 eV might induce the effective blocking of electrons, leading to an increase of RSh. Moreover, improvement in the long-term stability under atmospheric conditions was observed.
authors.affiliation: Department of Flexible and Printed Electronics, Jeonbuk National University, 664-14, Deokjin-dong, Deokjin-gu, Jeonju-si, Jeollabuk-do 561-756, Republic of Korea.
authors.forename: Da-Young
authors.initials: DY
authors.lastname: Lee
authors.affiliation: Department of Flexible and Printed Electronics, Jeonbuk National University, 664-14, Deokjin-dong, Deokjin-gu, Jeonju-si, Jeollabuk-do 561-756, Republic of Korea.
authors.forename: Seok-In
authors.initials: SI
authors.lastname: Na
authors.affiliation: Department of Nano & Chemical Engineering, Kunsan National University, 290-2, Miryong-dong, Gunsan-si, Jeollabuk-do 573-701, Republic of Korea. sskim@kunsan.ac.kr.
authors.forename: Seok-Soon
authors.initials: SS
authors.lastname: Kim