Thickness-Insensitive Anode Interface Layer for High-Efficiency Organic Solar Cells

Solution-Processed Thickness-Insensitive Molybdenum Oxide Hole-Transporting Layer Regulated by Reductive Ionic Liquid for Stable and Efficient Organic Solar Cells

Developing solution-processed, thickness-insensitive hole-transporting layers (HTLs) is a key challenge in scaling high-performance organic solar cells (OSCs). Here, a simple and efficient method is presented to produce highly conductive molybdenum oxide (MoOx) HTLs by n-doping ammonium heptamolybdate with a reductive ionic liquid (IL). Owing to the n-doping effect and inherent conductivity of IL, the conductivity of the 5% IL:MoOx significantly increased to 8.06 × 10-3 S m-1, surpassing traditional solution-processed MoOx HTLs. Moreover, the IL's multifunctional non-covalent adsorption sites and high boiling point help reduce electronic disorder and passivate parasitic traps, enhancing the overall performance. As a result, 5% IL:MoOx shows excellent versatility in commonly used photoactive systems and achieves a remarkable PCE of 19.55% in the D18:N3:L8-BO ternary system. This outperforms neat MoOx and PEDOT:PSS devices and represents as the highest reported value among single-junction OSCs with solution-processed MoOx HTLs. Additionally, devices with 5% IL:MoOx also exhibit superior stability compared to PEDOT:PSS devices. Furthermore, 5% IL:MoOx shows impressive thickness insensitivity, maintaining 83.3% of the optimum PCE even at a thickness of 150 nm. The exceptional PCE, versatility, stability, and thickness insensitivity of the 5% IL:MoOx HTL collectively highlight its potential as a substitute for PEDOT:PSS in scaling OSC production.

Reexamining the Role of Solution-Cast Ferroelectric Polymer Interlayer toward Enhanced Efficiency and Stability in Conventional Organic Solar Cells

Interfacial modification is crucial for achieving efficient and stable organic solar cells (OSCs). Herein, an N,N-dimethylformamide (DMF) solution-cast poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) interlayer was applied to enhance the efficiency and stability of a range of OSCs, and the underlying mechanism was revealed via morphological and device physics studies. DMF rinse during the P(VDF-TrFE) interlayer casting process strengthens π-π stacking of the active layer with fibril aggregation, optimized phase separation, and vertical component distribution, while the P(VDF-TrFE) interlayer with rich diploes contributes to increased surface potential and internal electric field. The synergistic effect of the P(VDF-TrFE) interlayer and DMF rinse increases the PCEs of PM6:IT-4F, PM6:C5-16, and PM6:L8-BO OSCs from 12.7, 17.9, and 18.2% to 13.1, 18.7, and 18.8%, respectively. Additionally, OSCs containing the P(VDF-TrFE) interlayer also showed improved storage stability.

Hole/Electron Transporting Materials for Nonfullerene Organic Solar Cells

Nonfullerene acceptor based organic solar cells (NF-OSCs) have witnessed rapid progress over the past few years owing to the intensive research efforts on novel electron donor and nonfullerene acceptor (NFA) materials, interfacial engineering, and device processing techniques. Interfacial layers including electron transporting layers (ETL) and hole transporting layers (HTLs) are crucially important in the OSCs for facilitating electron and hole extraction from the photoactive blend to the respective electrodes. In this review, the lates progress in both ETLs and HTLs for the currently prevailing NF-OSCs are discussed, in which the ETLs are summarized from the categories of metal oxides, metal chelates, non-conjugated electrolytes and conjugated electrolytes, and the HTLs are summarized from the categories of inorganic and organic materials. In addition, some bifunctional interlayer materials served as both ETLs and HTLs are also introduced. Finally, the prospects of ETL/HTL materials for NF-OSCs are provided.