Management of Crystallization Kinetics for Efficient and Stable Low‐Dimensional Ruddlesden–Popper (LDRP) Lead‐Free Perovskite Solar Cells

Abstract

Low‐dimensional Ruddlesden–Popper (LDRP) lead‐free perovskite has great potential due to its improved stability and oriented crystal growth, which is mainly attributed to the effective control of crystallization kinetics. However, the crystallization kinetics of LDRP lead‐free perovskite films are highly limited by Lewis theory. Here, the management of the crystallization kinetics of LDRP tin (Sn) perovskite films jointly controlled by Lewis adducts and the ion exchange process using a mixture of polar aprotic solvent dimethyl sulfoxide (DMSO) and ion liquid solvent methylammonium acetate (MAAc) (the process named as “L‐I”) is demonstrated. Homogeneous nucleated LDRP Sn perovskite films with average grain size close to 9 µm are achieved. Both low electron and hole defect density with a magnitude of 1016, high carrier mobility, and excellent electrical performance are obtained. As a result, the LDRP Sn perovskite solar cell (PSC) with power conversion efficiency (PCE) of 4.03% is achieved using a simple one‐step method without antisolvents, which is one of the best LDRP Sn PSCs. Most importantly, the PSC exhibits excellent stability with no degradation in PCE after 94 d in a nitrogen atmosphere owing to the high‐quality film and the inhibition of the oxidation of Sn2+.

Strategies for Improving the Stability of Tin‐Based Perovskite (ASnX3) Solar Cells

“…Later, Qiu et al reported for the first time the crystallization kinetics management of RP tin‐based perovskites controlled by Lewis adducts and ion exchange processes. [ 117 ] As a result, they obtained a film with a good average grain size of ≈9 µm; the best PCE was at 4.03%. It showed good stability and was placed in a nitrogen atmosphere for 94 d without degradation.…”

Oriented and Uniform Distribution of Dion–Jacobson Phase Perovskites Controlled by Quantum Well Barrier Thickness

“…The structure of the 2D layered perovskites is defined by the general formula A 2 A′ n − 1 M n X 3 n + 1 or AA′ n − 1 M n X 3 n + 1 , wherein the former, having monoammonium spacer cations, is named the Ruddlesden–Popper (RP) phase, and the latter, with diammonium spacer cations, is called the Dion–Jacobson (DJ) phase . At present, the research on RP phase perovskites is relatively mature, and various methods have been used to control crystal orientation and QW distribution, which are two critical factors influencing the performance. Hot casting was first reported to achieve vertical orientation, followed by the use of additives, shorter spacers, and the introduction of small amounts of FA + and Cs + .…”

Lead‐Free Tin‐Based Perovskite Solar Cells: Strategies Toward High Performance

“…The bandgaps can be tuned from 1.20 ( n = ∞) to 1.83 eV ( n = 1), whereas the CBMs are lifted too high to match with one of the TiO 2 . Qiu et al further optimized the crystallization kinetics of (BA) 2 (MA) n −1 Sn n I 3 n +1 and obtained uniform films with a grain size close to 9 μm . DMSO/methylammonium acetate (MAAc) were used as the mixed‐solvent and the crystallization undergoes an Ac − –I − ion‐exchange process.…”