Stirring-Time Control Approach to Manage Colloid Nucleation Size for the Fabrication of High-Performance Sn-Based Perovskite Solar Cells

Abstract

Colloidal nucleation is first observed to exist in a Sn-based perovskite solution, and its components and size are discovered to alter in real time with stirring time. Then, a simple stirring-time control approach is developed to manage the size of the colloids, and with continuous stirring for 3 days an optimal colloid with size <10 nm is confirmed to successfully form a continuous, dense, high-quality perovskite film. Herein, the colloids exist in the form of [SnI6]4– complete coordination compounds, with which a compact FA0.75MA0.25SnI3 perovskite film with reduced defects and enhanced crystallinity concentration is obtained as nucleation sites, and a planar inverted perovskite solar cell with a champion power conversion efficiency of 10.74% is eventually realized. This work provides a novel perspective to enhance perovskite film quality and thus device performance via controlling high-quality nucleation in precursor solution.

Prospects for Tin-Containing Halide Perovskite Photovoltaics

“…For solution processing, to understand crystallization we must begin in the liquid state, where perovskite solutions contain colloidal particles. Reported dynamic light scattering (DLS) measurements on Sn-containing solutions show up to three different size populations of particles, and in some cases the largest colloids or agglomerates present in solution are significantly larger than those for neat Pb. − The size distribution of the larger particles is also affected somewhat inversely to the behavior in Pb perovskites, where the addition of acid leads to a reduction in colloid size through reaction with DMF (dimethylformamide) . In current reports the addition of acids, bases, diammoniums, or chloride salts, , all seemingly increasing the average size of the large particles in Sn-containing perovskites.…”

“…These may exist as isolated complexes, as bridged chains, or within the colloidal species. , Moving to strongly coordinating halide ligands (Cl – > Br – > I – ), the absorption from more highly valent polyhalide plumbates is reduced . As there are few reports presenting absorption spectra of Sn perovskite solutions, and most being only SnI 2 , ,, the effect of solvents and halides on halogenostannate complexes (SnX m 2– m + ) in solution is yet to be understood, although undoubtedly impacts the crystallization.…”

Narrow Bandgap Metal Halide Perovskites for All-Perovskite Tandem Photovoltaics

“…Therefore, we would like to emphasize the great potential of structural modifications and solvent engineering approaches to address the current flaws in Sn-containing perovskite crystallization, avoiding the more common overdependence on additives. Unfortunately, most of the reports on absorption spectroscopy focus on neat Pb solutions, while examples for Sn-containing solutions remain scarce. ,− In fact, the relevance of polyhalide metalate complexes in mixed Sn−Pb perovskite precursor solutions and how to manipulate them is often disregarded and, as a consequence, key aspects of these solutions remain unexplored. Thus, we predict exhaustive absorption measurement studies on Sn-containing perovskite solutions to be critical for the advancement of the processing of these materials.…”

Synergistic Modulation of Sn-Based Perovskite Solar Cells with Crystallization and Interface Engineering

“…High-quality perovskite film is the first principle to achieve high-efficiency Sn-based PSCs. Precursor engineering, additive engineering, and component engineering have been mainly developed to improve the stability of Sn 2+ and the crystallization of Sn-based perovskite films [ 25 , 26 , 27 , 28 , 29 , 30 ]. Solvent engineering can effectively protect Sn 2+ in the precursor from oxidation and modulate the crystallization rate.…”