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The research team proposed a new strategy to effectively improve the photoelectric conversion efficiency of perovskite solar cells

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The research team proposed a new strategy to effectively improve the photoelectric conversion efficiency of perovskite solar cells

Recently, the team of Pan Xu, a researcher in the Energy Materials and Device Manufacturing Research Department of the Institute of Solid Physics, Hefei Institute of Material Science, Chinese Academy of Sciences, and the research group of Professor Xiao Zhengguo of the University of Science and Technology of Chinaperovskite solar cellProgress has been made in the study, the preparation of the ideal band gap of 1.33 eV of the lead-tin mixed perovskite as a solar cell absorption layer, through the directional anchoring strategy (STA) of the perovskite vacancy defects for precise passivation treatment, to obtain 22.51.photoelectric conversion efficiency(PCE) records that the photoelectric conversion efficiency is expected to surpass that of traditional lead-based perovskite solar cells.

At present, the highest photoelectric conversion efficiency of organometallic halide perovskite solar cells (PSCs) has been improved to 25.8 percent (25.7 percent certified). The band gap of the traditional lead-based perovskite material is in the range of 1.5-1.7 eV. According to the Shockley-Queisser(S-Q) model, when the band gap of the absorption layer is 1.33 eV, the battery has the highest theoretical limit efficiency. Partial or total substitution of Sn for Pb can reduce the band gap of perovskite. When the proportion of Sn is 20%, the band gap energy is reduced to the ideal value of about 1.33 eV. However, 20% Sn content is the critical value of the perovskite band gap change, where there are a large number of defects, resulting in non-radiative recombination resulting in serious open circuit voltage loss (VOCloss). According to previous studies, there are two main reasons for the loss of open circuit voltage: Sn2 + is easily oxidized to Sn4 +, causing serious self-p doping, forming Sn vacancies and introducing additional p-type charges; The reaction between Sn and organic components is stronger than that of Pb, which makes the crystallization process too fast and uncontrolled, resulting in poor film quality and increased defect density.

Based on this, the study used a directional selective anchoring strategy to passivate the perovskite, and obtained a 22.51% photoelectric conversion efficiency record of the ideal band gap perovskite solar cell. Studies have shown that the defects of bimetals in lead-tin hybrid perovskite solar cells are the main reason for their performance degradation. Therefore, the researchers used 2-phenylethylamine hydroiodide (PEAI) and ethylenediamine hydroiodide (EDAI) as co-modifiers to treat the surface of perovskites to selectively anchor the active sites related to Pb and Sn respectively and passivate the defects of the two metals. Finally, the open circuit voltage (VOC) of the lead-tin hybrid perovskite solar cell is greatly increased from 0.79V to 0.90V, and the loss of open circuit voltage is reduced to 0.43V. In addition, the device showed excellent stability, maintaining 80% of the initial efficiency after 2700 hours of storage in a nitrogen glove box.

This study provides an effective passivation mechanism for the management of metal dual source defects in lead-tin perovskite solar cells. The results were published in Advanced Materials. The research was supported by the National Key R & D Program, Anhui Provincial Outstanding Youth Fund and other projects.

Article from: Polaris power network