Scientific Achievement
Prof. Xu Pan and Dr. Jiajiu Ye from the Institute of Solid-State Physics (ISSP), Hefei Institutes of Physical Science (HIPS), Chinese Academy of Sciences and their cooperators Prof. Park Nam Gyu from the Sungkyunkwan University and Prof. Songyuan Dai from North China Electric Power University, investigated the non-uniformity of perovskite thin films along the vertical direction and analyzed the cause for this non-uniformity and its potential impact on the perovskite solar cells device.
Significance and Impact
They devised a strategy using 1-(phenylsulfonyl) pyrrole (PSP) as an additive to retard the segregation of cations in FA-Cs perovskites. The PSP-treated devices have a p-i-n structure and yielded a champion photon-to-electron conversion efficiency (PCE) of 26.1% (certified reverse PCE of 25.8% and certified steady-state PCE of 25.2%).
Research background
After rapid development, the efficiency of perovskite solar cells has significantly slowed down. High efficiency perovskite materials are often obtained by using cation doped components in a pure iodine system. The distribution of A-site cations within perovskite films critically affects the performance of the device. Although Cs has been widely used as a cation dopant in perovskite formulations, there are still concerns about the inhomogeneous distribution of cations. Thoroughly studying the out of plane distribution of cations not only helps to understand the carrier dynamics of perovskite phase, but also has the potential to further promote the efficiency development of perovskite solar cells.
Main research contents
The authors used 1- (phenylsulfonyl) pyrrole (PSP) to homogenize the cationic components in perovskite films. The synchrotron radiation X-ray absorption fine spectroscopy technique (XAFS) played a crucial role in demonstrating the effect of PSP molecules on the phase distribution of perovskite. The Pb LIII edge XAFS experiments were performed at the Radioactive Materials Beamline (BL13SSW). Five grazing incidence angles were designed in the experiment to obtain information at different depths inside the perovskite film (Figure 1).
Figure 1 Pb LIII edge XAFS at different depths within perovskite thin films
Bright Future Prospects
The findings in this work provide an in-depth understanding of phase segregation and suggest a promising strategy for accelerating commercialization of perovskite photovoltaics.
Contact
Jianrong Zeng，zengjr@sari.ac.cn, 021-20304853
Publication
Homogenizing out-of-plane cation composition in perovskite solar cells. Nature 2023, 624: 557–563
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