A Synergistic Precursor Regulation Strategy for Scalable Fabrication of Perovskite Solar Cells

Abstract

The nucleation and crystallization processes within solution‐processed deposition is key for obtaining perovskite films with high quality. Herein, the synergistic effect of Cs+, ligand solvent (tetramethylene sulfoxide, TMSO), and methylammonium ions (MA+) on nucleation and crystallization procedures of preparing perovskites films is studied. The results reveal that producing α‐phase nuclei in the intermediate‐phase film (a perovskite film formed by removing the solvent before annealing) is the key factor for obtaining α‐phase‐pure perovskites, wherein Cs+ is necessary for reducing the formation energy of the α‐phase. In addition, the nonvolatile ligand (TMSO) is used to inhibit rapid nucleation, because it can form a stable intermediate phase. Furthermore, the introduction of the volatile MA+ cations compound (MACl) combined with Cs+ contributed to the direct formation of α‐phase nuclei in the intermediate‐phase film, and ion exchange (between FA+ and MA+) occurs during the subsequent annealing process, which leads to the formation of large‐grain perovskite film with good crystallinity. Maximum power conversion efficiencies of 22.08% and 16.88% are obtained via this strategy for a perovskite solar cell on a small area (active area: 0.09 cm2) and a perovskite solar module (aperture area: 12.92 cm2), respectively.

Halogen Anion Management in Solution‐Processed Perovskite Films for Efficient Solar Cells

“…[ 16 ] Compared with MA + , the inorganic cation Cs + is also often used to promote the formation of black phase (while suppressing the formation of nonperovskite yellow phase), and more importantly, its introduction will not affect the stability of the FA‐based perovskite solution. [ 17,18 ]…”

“…[16] Compared with MA þ , the inorganic cation Cs þ is also often used to promote the formation of black phase (while suppressing the formation of nonperovskite yellow phase), and more importantly, its introduction will not affect the stability of the FA-based perovskite solution. [17,18] Halogen anions (such as I À , Br À , Cl À , etc.) play a key role in improving perovskite crystallization and adjusting the bandgap.…”

Method to Inhibit Perovskite Solution Aging: Induced by Perovskite Microcrystals

“…Perovskite solar cells (PSCs) have aroused wide attention due to their high photoelectric conversion efficiencies (PCEs) − and facile processing. − The improvement of stability of perovskite solutions and devices has more benefits for upscaling production and commercialization. − Formamidinium lead triiodide (FAPbI 3 )-based perovskite materials have shown great promise due to their superior initial performance and significantly enhanced thermal stability. , Usually, the precursor solutions were prepared by dissolving monomer precursors (FAI and PbI 2 ) in dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) solvents. However, under ambient conditions, FAPbI 3 favors a yellow nonperovskite polymorph (δ-FAPbI 3 , hexagonal) instead of the useful black perovskite polymorph (α-FAPbI 3 , cubic). , The additional introduction of low concentration of other cations, including cesium (Cs + ) or methylammonium (MA + ) in the precursor solution can construct FA-based mixed A-site perovskite films and can improve the phase stability of α-FAPbI 3 . ,, In addition, most of record PSCs prepared by precursor solution incorporated MACl additives to stabilize the perovskite structure, accelerate the crystallization process, and passivate defects. ,− …”