Selection of a Suitable Solvent Additive for 2-Methoxyethanol-Based Antisolvent-Free Perovskite Film Fabrication

Abstract

In this study, we compare various solvents with different Gutmann donor numbers as additives to improve the quality of perovskite films via an antisolvent-free process, using 2-methoxyethanol (2MOE) as the solvent. In 2MOE-based solutions, we found that the higher the donor number of the solvent, the lower the amount of the solvent required to form insoluble adducts. Furthermore, we found that N-methyl-2-pyrrolidone (NMP), which has a relatively low donor number and vapor pressure, can be added without a limitation to precipitation, while the degree of the intermediate phase in the as-deposited film is controlled by the amount of NMP added. We obtained pinhole-free and planar perovskite films by optimizing the amount of NMP added and fabricated devices based on NMP-assisted MAPbI3 and MAPbI3–x Cl x films, with efficiencies of 18.80 and 20.39%, respectively.

Green-solvent-processed formamidinium-based perovskite solar cells with uniform grain growth and strengthened interfacial contact via a nanostructured tin oxide layer

“…The shallow trap states can be presented at the SnO 2 -NRs/perovskite interface. 23 In particular, the PL peak shows a small blue-shift after the addition of Cl-BSM, indicating the reduction of shallow trap states. In other words, the Cl-BSM can efficiently passivate the trap states at the SnO 2 -NRs/ perovskite interface.…”

“…20 Besides DMSO, 2-methoxyethanol (2-Me) with lower toxicity was also used to replace DMF in many large-area fabrication processes of PSCs. [21][22][23][24][25][26] Without strong coordination ability, 2-Me often requires other toxic solvent additives, such as acetonitrile (ACN) 22 and N-methylpyrrolidone (NMP), 23 to achieve a desirable film morphology and device performance. Recently, a new family of greener solvents, triethyl phosphate (TEP) and trimethyl phosphate (TMP), 27,28 show comparable dissolving ability for perovskite precursors.…”

Co‐Solvent Engineering Contributing to Achieve High‐Performance Perovskite Solar Cells and Modules Based on Anti‐Solvent Free Technology

“…The maximum PCE of 20.39% based on MAPbI 3−x Cl x film prepared from the 2MOE-based solution containing NMP without anti-solvent could be achieved. [22] Most of the studies on PSCs fabricated by anti-solvent free technology process are based on MAPbI 3 -typed perovskite materials, which often lead to poor photovoltaic device stability and limit further improvement of PCE due to volatility of MA component in perovskite under temperature >80 °C and relatively wider bandgap (1.60 eV). [23] Besides, almost all research works that are based on anti-solvent free spinning-coated technology focus on the coordination interaction between solvent molecules and perovskite components (PbI 2 or FAI) that is the prerequisite for the formation of perovskite intermediate phase, but the mechanism of the intermolecular interaction between primary solvent like N, N-Dimethylformamide (DMF) and co-solvent like DMSO or NMP on nucleation process and formation process of intermediate phase has hardly been concerned.…”

Eco‐Friendly Solvent Engineered CsPbI2.77Br0.23 Ink for Large‐Area and Scalable High Performance Perovskite Solar Cells

“…Recently, several solo, binary, and ternary solvents have been introduced without DMF to prepare various compositions of green perovskite inks. [13,[15][16][17][18][19][20][21] Sun et al employed a mixture of methylammonium acetate and ACN to fabricate high-performance MAPbI x Br 3−x devices, in which the ACN minimized the coordination of the solvent and perovskite solutes that led to the formation of large micelles. [22] Cassella et al demonstrated up to 18.0% efficiency for the MAPbI 3 PSCs from a binary solvent of 2-ME and tetrahydrofuran.…”