Recent progress of eco-friendly manufacturing process of efficient perovskite solar cells

Abstract

Perovskite solar cells (PSCs) have the potential to produce solar energy at a low cost, with flexibility, and high power conversion efficiency (PCE). However, there are still challenges to be addressed before mass production of PSCs, such as prevention from degradation under external stresses and the uniform, large-area formation of all layers. Among them, the most challenging aspect of mass production of PSCs is creating a high-quality perovskite layer using environmentally sustainable processes that are compatible with industry standards. In this review, we briefly introduce the recent progresses upon eco-friendly perovskite solutions/antisolvents and film formation processes. The eco-friendly production methods are categorized into two: (1) employing environmentally friendly solvents for perovskite precursor ink/solution, and (2) replacing harmful, volatile antisolvents or even limiting their use during the perovskite film formation process. General considerations and criteria for each category are provided, and detailed examples are presented, specifically focused on the works have done since 2021. In addition, the importance of controlling the crystallization behavior of the perovskite layer is highlighted to develop antisolvent-free perovskite formation methods.

Keywords: Antisolvent-free fabrication; Environmentally friendly fabrication; Green solvent systems; Perovskite solar cells; Scale-up production.

Fig. 1

Representative examples and criteria for proper selection of solvents and antisolvents

Fig. 2

Schematic illustration of perovskite formation processes: perovskite precursor deposition, phase conversion, and crystallization

Fig. 3

a Schematic illustration of a solution-shearing method and cross-sectional Scanning Electron Microscope (SEM) images of perovskite layer on FTO/c-TiO₂/mp-TiO₂ substrate prepared at different conditions of DMF/DMSO solution and ACN/MA solution. Reprinted with permission from [29]. Copyright 2022, Elsevier. b the full and c enlarged FTIR spectra result of TEP, intermediate phase, and perovskite (annealed). Reprinted with permission from [30]. Copyright 2022, Elsevier d Schematic of the perovskite layer deposition processes based on ETL substrate. Reprinted with permission from [36]. Copyright 2023, Royal Society of Chemistry

Fig. 4

a Schematic illustration of device architecture and cross-sectional SEM image of a PSC fabricated from the DMSO solution system. Reprinted with permission from [32], Copyright 2021, American Chemical Society. b UV—vis spectra of perovskite precursors in GVL and GBL. Reprinted with permission from [34], Copyright 2021, The Authors. Energy Technology published by Wiley-VCH GmbH c Solubility test of FAPbI₃ dissolved in EtOH, EtOH/DMA mixed solvent, and EtOH/DMA solution with PACl d FTIR spectra of the precursor solutions. Characteristic peaks between 1620 and 1635 cm^− 1 are assigned to the C = O stretching peaks of DMA. e Change of perovskite films with containing different types of RNH₃Cl. Reprinted with permission from [37], Copyright 2022, The Author(s), under exclusive license to Springer Nature Limited. f Schematic of perovskite crystal formation in 2-ME-CHP solution system. Reprinted with permission from [39], Copyright 2021, Elsevier. g SEM images of perovskite film change according to the amount of NMP additives. Reprinted with permission from [38], Copyright 2022, American Chemical Society

Fig. 5

a Film morphologies depending on antisolvents. Reprinted with permission from [47], Copyright 2021, The Authors. SusMat published by Sichuan University and John Wiley & Sons Australia, Ltd. b Illustration of in-situ and post- CTAC treatment. Reprinted with permission from [48], Copyright 2021, Science China Press. c Illustration depicting the interaction between DMSO and FA⁺, and the preferred (111) crystal orientation. Reprinted with permission from [49], Copyright 2022, Wiley-VCH GmbH d Interaction between the C = O functional groups of acetylacetone and PbI₂. Reprinted with permission from [51], Copyright 2021, Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. e Illustration of hydrogen bond between a C= O group of diethyl carbonate and DMSO and FTIR spectrum presenting interaction between them. Reprinted with permission from [52], Copyright 2022, Elsevier B.V. f Uniform and pinhole-free perovskite films, made via green solvents. Reprinted with permission from [53], Copyright 2021, Elsevier B.V

Fig. 6

Schematic representation of perovskite film formation processes, and La Mer diagram with corresponding illustration of film morphologies for different cases. The degree of supersaturation level determines the number of seeds formed by “burst” nucleation and final morphology of the film after growth stage

Fig. 7

Schematic illustration of a vacuum-assisted solution processing, and d spin coating. Reprinted with permission from [58], Copyright 2016, American Association for the Advancement of Science. b Illustration showing surface treatment of vacuum-assisted perovskite films. Reprinted with permission from [59], Copyright 2021, Royal Society of Chemistry. c Illustration of 4-guanidinobutanoic acid forming 2D perovskites at the grain boundaries. Reprinted with permission from [60], Copyright 2021, The Authors. Advanced Science published by Wiley-VCH GmbH e Pre-synthesized 3D MAPbCl₃ and 1D ABTPbI₃) microcrystals as seed crystals during the film formation. Reprinted with permission from [61], Copyright 2022, Wiley-VCH GmbH f Schematic illustration of inkjet printing perovskite films and SEM images depicting film morphologies given by the balance between amounts of PbAc₂ and PbCl₂. Reprinted with permission from [47], Copyright 2021, Wiley-VCH GmbH g Schematic illustration of gravure printing process and the resulting films. Reprinted with permission from [62], Copyright 2021, The Author(s), published by Elsevier

Fig. 8

a Gas-mediated solid-liquid conversion process and D-bar coating of the solution. Reprinted with permission from [63], Copyright 2019, American Chemical Society. b The crystallization process of perovskite precursor solution employing ACN and 2-ME as the solvent and its rapid blading method. Reprinted with permission from [17], Copyright 2019, The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. c Fabrication of perovskite films with 2-ME and CHP mixed solution. Reprinted with permission from [39], Copyright 2021, Elsevier Inc. d The role of NMP in precursor solution. Reprinted with permission from [38], Copyright 2022, American Chemical Society. e The addition of RNH₃Cl, enabling the formation of a soluble PbI₂-HCl complex. Reprinted with permission from [37], Copyright 2022, The Author(s), under exclusive license to Springer Nature Limited. f Effect of MABr, releasing residual lattice strain to stabilize the crystal structure. Device structure with green solvents used for each layer. Reprinted with permission from [64], Copyright 2021, Royal Society of Chemistry