Research progress of high-efficiency and stable perovskite solar cells of the Institute of Semiconductors

Perovskite solar cells have the advantages of low cost and high photoelectric conversion efficiency
.
After more than ten years of rapid development, the efficiency of perovskite single-junction cells has exceeded 25%, and the efficiency of perovskite-based multi-junction tandem cells has exceeded 30%.
Perovskite solar cells are considered to be photovoltaics with considerable application potential in the future.
one of the technologies
.

Photoelectric conversion efficiency is one of the core indicators of solar cells.
In order to achieve high-efficiency perovskite solar cells, the secondary phase lead iodide (PbI ₂ ) that can form an I-type heterojunction energy level structure with perovskite is often used.
to block carrier recombination at polycrystalline perovskite grain boundaries or surface defects
.
Previously, the Institute of Semiconductors, Chinese Academy of Sciences found that it is difficult for perovskite cells based on secondary phase PbI ₂ to take into account both efficiency and stability (Advanced Materials, 2017, 29, 1703852), because the presence of the PbI ₂ secondary phase may provide calcium The decomposition of titanite and the channel of ion movement make perovskite materials and battery devices less stable in the long-term and prone to large hysteresis
.
Therefore, how to design a stable secondary phase that can not only passivate perovskite defects, but also obtain stable perovskite light-absorbing materials, so as to achieve both high-efficiency and stable perovskite solar cells is an important topic in this field.
one
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_{Recently, a team led by You Jingbi, a researcher at the Institute of Semiconductors, found that by introducing a small amount of rubidium chloride (RbCl) into the perovskite material, the common secondary phase PbI 2} that causes perovskite instability can be transformed into a new thermally stable and Good chemical stability (PbI ₂ ) ₂ RbCl (abbreviated as PIRC) (Figure 1A, B)
.
The research realized that the thermal stability of the perovskite material was greatly improved under the condition of 85 ^o
C, and the ion migration barrier of the perovskite material was increased by 3 times, and the ion migration was effectively suppressed (Figure 1C, D) .
In addition, the study found that by suppressing PbI ₂ , the problem of band enlargement caused by the strong confinement of the perovskite/PbI ₂ interface was eliminated, the band gap of the perovskite material was reduced, and the absorption range of sunlight was expanded
.
Based on the obtained perovskite material with high stability and extended light absorption, the team developed a perovskite solar cell with a certified efficiency of 25.
6% (Fig.
2A), the world's highest published single-junction perovskite solar cell.
efficiency
.
The 1000-h placement and accelerated aging at 85°C retained 96% and 80% of the initial efficiency, respectively, of the battery device (Fig.
2B,C)
.
This work simultaneously achieves high photoelectric conversion efficiency and high stability of perovskite solar cells, laying a solid foundation for the further development and industrialization of perovskite cells
.

The related research results were published in Science under the title of Inactive (PbI ₂ ) ₂ RbCl stabilizes perovskite films for efficient solar cells
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The research work is supported by the National Key R&D Program, the National Science Fund for Distinguished Young Scholars, the Chinese Academy of Sciences Innovation Interdisciplinary Team, the National Science Fund for Outstanding Young Scholars, Central South University, Beijing Municipal Science and Technology Commission, as well as Central South University, Shanghai Synchrotron Radiation Light Source, Wuhan University,
etc.

Fig.
1.
A, Scanning electron microscope photo of perovskite with PIRC secondary phase; B, X-ray diffraction pattern of perovskite film with and without PIRC (the inset is a partial enlarged view); C and D, respectively, with and without PIRC Plot of perovskite conductance versus temperature
.

Figure 2.
A.
The third-party authoritative organization American Newport certification, the certification efficiency is 25.
6%, and the illustration is the certification efficiency curve; B.
The current-voltage curve of the placement of the PIRC device with or without stable secondary phase; C.
With or without stable secondary Stability of phase PIRC devices under accelerated aging at 85°C
.