The silicon surface texture significantly affects the current density and efficiency of perovskite/silicon tandem solar cells. However, only a few studies have explored fabricating perovskite on textured silicon and the effect of texture on perovskite films because of the limitations of solution processes. Here we produce conformal perovskite on textured silicon with a dry two-step conversion process that incorporates lead oxide sputtering and direct contact with methyl ammonium iodide. To separately analyze the influence of each texture structure on perovskite films, patterned texture, high-resolution photoluminescence (μ-PL), and light beam-induced current (μ-LBIC), 3D mapping is used. This work elucidates conformal perovskite on textured surfaces and shows the effects of textured silicon on the perovskite layers with high-resolution 3D mapping. This approach can potentially be applied to any type of layer on any type of substrate.

Radio frequency (RF) magnetron-sputtered TiO 2 (RS-TiO 2 ) is investigated as a hole-blocking layer for perovskite solar cells. RS-TiO 2 shows conformal, dense, and efficiently electron transferable properties. Power conversion efficiency (PCEs) of 20.9% were obtained with high reproducibility. RS-TiO 2 also showed potential in the upscaling process, transparent perovskite, and perovskite/silicon 4-terminal tandem solar cells. With increasing active area 40 times from 0.075 cm 2 to 3 cm 2 without dividing areas by laser patterning, less than 4% open-circuit voltage (V oc ) and shortcircuit current density (J sc ) drops were observed. This means RS-TiO 2 layers can maintain their film quality even when the area size is increased. Furthermore, by applying RS-TiO 2 to transparent perovskite solar cells and perovskite/silicon 4-terminal tandem solar cells, PCEs of 16.7% and 23.1% were obtained, respectively.

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Current density plays a substantial role in monolithic tandem solar cells; however, it is difficult to control because subcells and auxiliary layers are stacked and serially connected vertically to obtain higher voltages. The vertically stacked structure intrinsically triggers inevitable parasitic absorption. In current typical perovskite/silicon two-terminal (2-T) tandem solar cells, 5−10 layers are placed on the light path, even though they are not current generating layers. These layers usually include transparent window layers, buffer layers, carrier extraction layers, and recombination layers. Therefore, the development of top contact-free architectures to reduce parasitic absorption in 2-T tandem solar cells is required for achieving high efficiency. In this study, a top contact-free perovskite/silicon 2-T tandem solar cell with quasi-interdigitated intermediate electrodes (Q-IDIEs) is reported for the first time. Several layers placed above the perovskite layer in conventional devices are relocated to the backside of the perovskite. The Q-IDIE, composed of a patterned Ni/NiO X shell above the full-deposited TiO 2 , was fabricated by the following processes: photolithography, lift-off, and oxidation. The device results in 4.23% efficiency with an open-circuit voltage of 1.54 V. This tandem architecture is expected to be a breakthrough for overcoming the theoretical efficiency limit of single-junction solar cells with further optimization.

Perovskite Solar Cells In article number http://doi.wiley.com/10.1002/solr.202300214, Kang, Lee, and co‐workers presented a novel approach for fabricating perovskite films using a sputtering process. They applied post‐processes to enhance the film properties and the electrical characteristics of perovskite solar cells. These processes enable the deposition of uniform perovskite films on large‐area textured silicon substrates, opening new possibilities for efficient solar energy conversion.

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Conformal deposition of perovskite films on textured silicon surfaces using a dry process is crucial for producing high‐performance perovskite/silicon tandem solar cells. Herein, a radio frequency magnetron sputtering process is used with a PbI2 target to deposit precursor films. Iodination, thermal annealing, and dimethyl sulfoxide treatment are employed as posttreatment processes to improve the stoichiometry, crystallinity, and surface morphology of the PbI2 precursor. The precursor films are converted into perovskite using direct contact conversion process, and the interfacial and bulk properties are enhanced by methylamine vapor annealing to fabricate perovskite solar cells with a power conversion efficiency of 12.2%. Also, 18.3% efficiency is confirmed at a wider voltage sweep range, which suggests that further efficiency improvement is possible by removing defects inside the perovskite. Finally, uniform perovskite films are conformally deposited on a 25 cm2 textured silicon surface. With such high‐efficiency potential and conformality, the method of sputtering PbI2 can open a new way to fabricate perovskite/silicon tandem solar cells.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.