Defect Passivation of Perovskite Films for Highly Efficient and Stable Solar Cells

Abstract

Perovskite solar cells (PSCs) have been introduced as an attractive photovoltaic technology over the past decade due to their low‐cost processing, earth‐abundant raw materials, and high power conversion efficiencies (PCEs) of up to 25.2%. However, the relatively high density of defects within the bulk, grain boundaries, and surface of polycrystalline perovskite films acts as recombination centers and facilitates ion migration, lowering the theoretical PCE ceiling, often leading to inferior device stability. Therefore, understanding the defect sources and developing passivation methods are key factors for reaching higher PCEs and stabilities in perovskite photovoltaics. Herein, various passivation methods, including bulk and surface treatment of perovskite films, are explored. In the bulk treatment, the passivating agents should be directly added to the perovskite precursor. However, in the surface treatment method, the surface of perovskite films can be treated by inducing passivating agents during the intermediate phase or after annealing steps, denoted here as in‐film or surface posttreatment. In addition, different kinds of passivating agents are categorized based on their functional groups. Finally, the outline directions to minimize the defects in perovskite films are highlighted.

Recent Progress in Mixed A‐Site Cation Halide Perovskite Thin‐Films and Nanocrystals for Solar Cells and Light‐Emitting Diodes

“…The mixed A‐cation LHP NCs can be synthesized directly using the mixture of desired A‐cation precursors or by applying post‐synthetic A‐cation exchange and cross‐exchange on pre‐synthesized mono‐cation LHP NCs, as illustrated in Figure . The direct synthesis can be carried out by classical methods such as hot‐injection [ 48–175 ] or reprecipitation [ …”

Encapsulation Strategies for Highly Stable Perovskite Solar Cells under Severe Stress Testing: Damp Heat, Freezing, and Outdoor Illumination Conditions

“…Many studies report that significant changes occur in perovskite films during illumination or application of bias, including halide segregation, ion migration, and compositional degradation due to defect states on the surface and bulk or grain boundaries of perovskite films. ,, On the other hand, it has been demonstrated that defect states can spread out irreversibly under humid conditions due to severe degradation. , Therefore, an efficient device encapsulation can suppress these negative behaviors in PSCs at long-term illumination and applied bias.…”

Tin-based halide perovskite materials: properties and applications

“…Generally, an ideal additive, depending on its functional group, should have an effective chemical interaction with perovskite components to improve the quality of thin films. 57,58 Firstly, pyrazine was added to tin-based perovskite precursor as a co-additive with SnF 2 to suppress the Sn 2+ oxidation and homogeneous dispersion of SnF 2 in the thin film by forming the SnF 2 –pyrazine complex. 59 The SnF 2 –pyrazine complex forms by strong d → π* back-donation coordination from tin( ii ) halide to the pyrazine ring.…”