Binary Solvent System Used to Fabricate Fully Annealing‐Free Perovskite Solar Cells

• Published in: Advanced energy materials 2023-03, Vol.13 (11), p.n/a
• Main Authors: Cassella, Elena J., Spooner, Emma L.K., Smith, Joel A., Thornber, Timothy, O'Kane, Mary E., Oliver, Robert D.J., Catley, Thomas E., Choudhary, Saqlain, Wood, Christopher J., Hammond, Deborah B., Snaith, Henry J., Lidzey, David G.
• Format: Article
• Language: English
• Subjects: Annealing; annealing free; Deposition; Energy conversion efficiency; Ethanol; High temperature; Lead compounds; Metal halides; perovskite solar cells; Perovskites; Photovoltaic cells; Production costs; Roller coating; Room temperature; Self-assembly; self‐assembled monolayers; Solar cells; solar energy; Solvents; Tetrahydrofuran; Thin films; Vapor pressure
• ISSN: 1614-6832; 1614-6840
• DOI: 10.1002/aenm.202203468

High temperature post‐deposition annealing of hybrid lead halide perovskite thin films—typically lasting at least 10 min—dramatically limits the maximum roll‐to‐roll coating speed, which determines solar module manufacturing costs. While several approaches for “annealing‐free” perovskite solar cells (PSCs) have been demonstrated, many are of limited feasibility for scalable fabrication. Here, this work has solvent‐engineered a high vapor pressure solvent mixture of 2‐methoxy ethanol and tetrahydrofuran to deposit highly crystalline perovskite thin‐films at room temperature using gas‐quenching to remove the volatile solvents. Using this approach, this work demonstrates p‐i‐n devices with an annealing‐free MAPbI3 perovskite layer achieving stabilized power conversion efficiencies (PCEs) of up to 18.0%, compared to 18.4% for devices containing an annealed perovskite layer. This work then explores the deposition of self‐assembled molecules as the hole‐transporting layer without annealing. This work finally combines the methods to create fully annealing‐free devices having stabilized PCEs of up to 17.1%. This represents the state‐of‐the‐art for annealing‐free fabrication of PSCs with a process fully compatible with roll‐to‐roll manufacture. The cost of manufacturing solar cells is determined by their roll‐to‐roll coating speed. Lengthy annealing steps severely limit the effective coating speed of perovskite solar cells (PSCs). Here, a high vapor‐pressure precursor ink is solvent‐engineered to entirely circumvent such annealing treatments. Fully annealing‐free p‐i‐n PSCs—entirely compatible with roll‐to‐roll processing—demonstrate power conversion efficiencies (PCEs) over 17%.