Hot‐Casting‐Assisted Liquid Additive Engineering for Efficient and Stable Perovskite Solar Cells

Abstract

High‐performance inorganic–organic lead halide perovskite solar cells (PSCs) are often fabricated with a liquid additive such as dimethyl sulfoxide (DMSO), which retards crystallization and reduces roughness and pinholes in the perovskite layers. However, DMSO can be trapped during perovskite film formation and induce voids and undesired reaction byproducts upon later processing steps. Here, it is shown that the amount of residual DMSO can be reduced in as‐spin‐coated films significantly through use of preheated substrates, or a so‐called hot‐casting method. Hot casting increases the perovskite film thickness given the same concentration of solutions, which allows for reducing the perovskite solution concentration. By reducing the amount of DMSO in proportion to the concentration of perovskite precursors and using hot casting, it is possible to fabricate perovskite layers with improved perovskite–substrate interfaces by suppressing the formation of byproducts, which increase trap density and accelerate degradation of the perovskite layers. The best‐performing PSCs exhibit a power conversion efficiency (PCE) of 23.4% (23.0% stabilized efficiency) under simulated solar illumination. Furthermore, encapsulated devices show considerably reduced post‐burn‐in decay, retaining 75% and 90% of their initial and post‐burn‐in efficiencies after 3000 h of operation with maximum power point tracking (MPPT) under high power of ultraviolet (UV)‐containing continuous light exposure.

PbI2 Reagent Impurities Catalyze Mixed-Cation Halide Perovskite Ink Degradation

“…The presence of PbO (which does not dissolve well) caused nearly complete degradation (96%), which is also consistent with the fact that PbO can react with 3 equivalents of MAI to make MAPbI 3 and H 2 O, releasing 2 equivalents of methyl­amine. It is most notable that water has such a small effect on the MFA reaction, given a recent report, yet logical since DMSO more readily accepts a proton than H 2 O in these aprotic solvent environments. − …”

Kinetic Control of Solvate Intermediate Evolution for High-Performance Perovskite Solar Cells by the Facial Mask Incubation Technique

“…19 In addition, Rand et al spontaneously employed substrate per-heated treatment and solvent regulation to reduce the adducts and intermediate species in precursor films, thus suppressing the formation of byproducts and reducing solvate residual. 18,20 modulation of precursor components is also a widely used approach to produce the high-pure perovskite phase. Zhang et al found that cesium cations required relatively lower energy to diffuse into IP frameworks compared with DMSO, thus promoting the release of solvent molecules; consequently, a well-crystallized cesium-doped perovskite film without any impurity phases was obtained at near room temperature.…”

Secondary Anti‐Solvent Treatment for Efficient 2D Dion–Jacobson Perovskite Solar Cells

“…[1][2][3][4] However, the in the film will produce some by-products that will affect the perovskite phase purity and device performance. [18,19] It is revealed that the 2D perovskite films suffer from more severe defects than 3D films, [20] and the surface trap density is twoorder higher than that of bulk materials. [21] So most researchers have focused on surface passivation to improve the efficiency of 2D PSCs.…”