title: Synthesis of atomically thin transition metal disulfides for charge transport layers in optoelectronic devices.
abstract: Metal sulfides (MeS2) such as MoS2 and WS2 were used as charge transport layers in organic light-emitting diodes (OLEDs) and organic photovoltaic (OPV) cells in order to enhance the stability in air comparing to poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (
  PSS). MeS2 layers with a polycrystalline structure were synthesized by a chemical deposition method using uniformly spin-coated (NH4)MoS4 and (NH4)WS4 precursor solutions. The ultraviolet-ozone (UV-O3) treatment on MeS2 leads to the removal of the surface contaminants produced by the transfer process, resulting in a uniform surface and an increase of the work function. The maximum luminance efficiencies of the OLEDs with UV-O3-treated MoS2 and WS2 were 9.44 and 10.82 cd/A, respectively. The power conversion efficiencies of OPV cells based on UV-O3-treated MoS2 and WS2 were 2.96 and 3.08%, respectively. These values correspond to over 95% of those obtained with (
  PSS) based devices. Furthermore, OLEDs and OPV cells based on MeS2 showed two to six times longer stability in air compared with
  PSS based devices. These results suggest that UV-O3-surface-treated MeS2 could be a promising candidate for a charge transport layer in optoelectronic devices.
authors: †Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul 151-744, Republic of Korea.
authors: Ki Chang
authors: KC
authors: Kwon
authors: ‡School of Chemical Engineering and Materials Science, Chung-Ang University, Seoul 156-756, Republic of Korea.
authors: Cheolmin
authors: C
authors: Kim
authors: ‡School of Chemical Engineering and Materials Science, Chung-Ang University, Seoul 156-756, Republic of Korea.
authors: Quyet Van
authors: QV
authors: Le
authors: §Department of Materials Science, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk 790-784, Republic of Korea.
authors: Seungo
authors: S
authors: Gim
authors: †Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul 151-744, Republic of Korea.
authors: Jong-Myeong
authors: JM
authors: Jeon
authors: §Department of Materials Science, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk 790-784, Republic of Korea.
authors: Ju Young
authors: JY
authors: Ham
authors: §Department of Materials Science, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk 790-784, Republic of Korea.
authors: Jong-Lam
authors: JL
authors: Lee
authors: †Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul 151-744, Republic of Korea.
authors: Ho Won
authors: HW
authors: Jang
authors: ‡School of Chemical Engineering and Materials Science, Chung-Ang University, Seoul 156-756, Republic of Korea.
authors: Soo Young
authors: SY
authors: Kim
keywords: chemical vapor deposition; hole injection layer; organic light-emitting diodes; organic photovoltaics; transition metal disulfide