Post‐Treatment of Metal Halide Perovskites: From Morphology Control, Defect Passivation to Band Alignment and Construction of Heterostructures

Abstract

Metal halide perovskite solar cells (PSCs) have witnessed a swift increase in power conversion efficiency in the past decade, emerging as one of the most promising next‐generation photovoltaic technologies for commercialization and low‐carbon energy generation. Through significant efforts in optimizing the processing techniques, high‐quality perovskite thin films can now be prepared with polycrystalline morphologies consisting of monolayer grains. Nevertheless, defects and microstructural disorders still form at the surface/heterointerface and in the bulk of the films. Post‐treatment of the as‐crystallized films has been intensively investigated for passivating these defects, being proved effective for improving the device performance. In this review, the versatile strategies for post‐treating the surface of perovskite thin films toward morphology control, defect passivation, and band alignment are discussed. The tailored surface properties are correlated to charge dynamics at interfaces and photovoltaic performance of PSCs. Since the perovskite heterostructures prepared by simple post‐treatments may suffer from degradation at high temperatures, the recent advances in preparing phase‐pure and stable perovskite heterostructures are also discussed. Finally, a perspective elaborating future opportunities for further enhancing the efficiency and stability of PSCs is provided.

Improved Performance and Stability of Quasi-Two-Dimensional Perovskite Solar Cells by Post-treatment with Acetaminophen

“…Post-treatment of the perovskite can induce a secondary crystal growth of the perovskite film. For the post-treatment by AMP with an optimized concentration of 2 mg/mL, the small-sized perovskite crystals could be quickly dissolved and regrown into larger crystals, − in which the crystal dissolution and the regrowth are balanced. While for the post-treatment by AMP with a large concentration of 3 mg/mL, the crystal dissolution is more than the crystal regrowth due to the excess AMP molecules; thus, the dissolved perovskite crystals are not completely regrown into crystals, and the perovskite film is destroyed.…”

LiTFSI-Free Hole Transport Materials for Robust Perovskite Solar Cells and Modules with High Efficiencies

“…Metal-halide perovskite solar cells (PSCs) have shown great efficiency improvements in recent years, making them a subject of intense attention and research. − Benefited from the continuous efforts on perovskite composition optimization, interfacial passivation, and new material developments, the power conversion efficiency (PCE) of PSC has been improved from ∼3.0% to more than 26.0%. − Apart from the PCE, the stability, scalability, and cost of PSCs are now the most challenging issues that limits their commercialization. , …”

NaCl-Induced PbI2 Passivation Enhancement on Cs0.17FA0.83Pb(I0.83Br0.17)3 Thin Films for Perovskite Solar Cells

“…Low-cost fabrication technologies for a perovskite absorption layer include the use of a solution-based method such as spin-coating with inexpensive precursors, which relates to low-cost technology. , However, undesirable defects such as vacancies, noncoordinate ions, and unreacted precursors frequently emerge in solution-processed perovskite films not only in the bulk but also on the surface . For example, unreacted PbI 2 is the kind of defect that is frequently observed and that has been reported to hasten the decline in performance in the long run. , Despite this, PbI 2 is reported to be a two-edged sword that does not cause much harm to perovskite and may help boost performance if it exists properly. − Therefore, it is crucial to develop strategies that effectively handle the formation of defects.…”