Author:

Keywords:

Science & Technology, Physical Sciences, Technology, Chemistry, Multidisciplinary, Chemistry, Physical, Nanoscience & Nanotechnology, Materials Science, Multidisciplinary, Physics, Applied, Physics, Condensed Matter, Chemistry, Science & Technology - Other Topics, Materials Science, Physics, cost-effective and scalable methods, fluorinated perylene-diimides, fluorination, high device performance, INTERFACIAL MATERIALS, FILL FACTOR, EFFICIENT, RECOMBINATION, ELECTRODES, DENSITY, VOLTAGE, C14/19/079#55221587, 12Y7221N#55744511, IBOF/21/085#56129725, C3/19/046#55510265, 02 Physical Sciences, 03 Chemical Sciences, 09 Engineering, 34 Chemical sciences, 40 Engineering, 51 Physical sciences

Abstract:

Organic solar cells (OSCs) have experienced rapid progress with the innovation of near-infrared (NIR)-absorbing small-molecular acceptors (SMAs), while the unique electronic properties of the SMAs raise new challenges in relation to cathode engineering for effective electron collection. To address this issue, two fluorinated perylene-diimides (PDIs), PDINN-F and PDINN-2F, are synthesized by a simple fluorination method, for application as cathode interlayer (CIL) materials. The two bay-fluorinated PDI-based CILs possess a lower lowest unoccupied molecular orbital (LUMO) energy level of ≈-4.0 eV, which improves the energy level alignment at the NIR-SMAs (such as BTP-eC9)/CIL for a favorable electron extraction efficiency. The monofluorinated PDINN-F shows higher electron mobility and better improved interfacial compatibility. The PDINN-F-based OSCs with PM6:BTP-eC9 as active layer exhibit an enhanced fill factor and larger short-circuit current density, leading to a high power conversion efficiency (PCE) exceeding 18%. The devices with PDINN-F CIL retain more than 80% of their initial PCE after operating at the maximum power point under continuous illumination for 750 h. This work prescribes a facile, cost-effective, and scalable method for the preparation of stable, high-performance fluorinated CILs, and instilling promise for the NIR-SMAs-based OSCs moving forward.