Highly efficient organic solar cells based on a robust room-temperature solution-processed copper iodide hole transporter. (September 2015)

• Record Type: Journal Article
• Authors: Zhao, Kui; Ngongang Ndjawa, Guy O.; Jagadamma, Lethy Krishnan; Labban, Abdulrahman El; Hu, Hanlin; Wang, Qingxiao; Li, Ruipeng; Abdelsamie, Maged; Beaujuge, Pierre M.; Amassian, Aram
• Is Part Of: Nano energy. Volume 16(2015:Sep.)
• Page Start: 458
• Page End: 469
• Publication Date: 2015-09
• Subjects: Organic photovoltaics -- Organic solar cells -- Copper iodide -- Hole transporting layer -- Buffer layer -- Solution processed; Nanoscience -- Periodicals; Nanotechnology -- Periodicals; Nanostructured materials -- Periodicals; Power resources -- Technological innovations -- Periodicals; Nanoscience; Nanostructured materials; Nanotechnology; Power resources -- Technological innovations; Periodicals; 621.042
• DOI: 10.1016/j.nanoen.2015.07.018
• Languages: English
• ISSNs: 2211-2855

Abstract

Abstract: Achieving high performance and reliable organic solar cells hinges on the development of stable and energetically suitable hole transporting buffer layers in tune with the electrode and photoactive materials of the solar cell stack. Here we have identified solution-processed copper(I) iodide (CuI) thin films with low-temperature processing conditions as an effective hole-transporting layer (HTL) for a wide range of polymer:fullerene bulk heterojunction (BHJ) systems. The solar cells using CuI HTL show higher power conversion efficiency (PCE) in standard device structure for polymer blends, up to PCE of 8.8%, as compared with poly(3, 4-ethylenedioxy-thiophene):poly(styrenesulfonate) (PEDOT:PSS) HTL, for a broad range of polymer:fullerene systems. The CuI layer properties and solar cell device behavior are shown to be remarkably robust and insensitive to a wide range of processing conditions of the HTL, including processing solvent, annealing temperature (room temperature up to 200 °C), and film thickness. CuI is also shown to improve the overall lifetime of solar cells in the standard architecture as compared to PEDOT:PSS. We further demonstrate promising solar cell performance when using CuI as top HTL in inverted device architecture. The observation of uncommon properties, such as photoconductivity of CuI and templating effects on the BHJ layer formation, is also discussed. This study points to CuI as being a good candidate to replace PEDOT:PSS in solution-processed solar cells thanks to the facile implementation and demonstrated robustness of CuI thin films. Graphical abstract: Solution-processed copper(I) iodide (CuI) is demonstrated to be an effective hole transporting layer (HTL) for several polymer:fullerene bulk heterojunction (BHJ) systems, leading to demonstration of efficiency up to 8.8% in the standard device configuration and in many cases surpassing the performance of devices based on PEDOT:PSS as HTL. Highlights: Copper iodide (CuI) is demonstrated as an effective hole transporting layer (HTL). CuI-based solar cells yield highly efficient (>8%) polymer:fullerene solar cells. CuI can be solution processed at room temperature. Extremely robust and reliable, yielding consistently good solar cells.