organic - inorganic hybrid perovskite solar cells have achieved rapid development in recent years, and the photoelectric conversion efficiency has been comparable to that of monocrystalline silicon cells. All-inorganic perovskites represented by CsPbI3 have excellent light and thermal stability, and their ~1.7eV band gap is an ideal choice for perovskite / silicon tandem solar cells top cells. CsPbI3 All-inorganic perovskites Mineral solar cells have become a new research hotspot and attracted much attention. Despite this, the CsPbI3 perovskite absorption layer has problems such as a relatively high defect density and serious non-radiative charge recombination, which leads to a large loss of the battery open circuit voltage and low battery efficiency. Improving the quality of CsPbI3 polycrystalline films, reducing defect density and improving phase stability are of great significance for further improving CsPbI3 battery efficiency and stability.
Figure 1. J-V characteristic curve of CsPbI3 perovskite cell prepared based on PTAI low-dimensional perovskite passivation strategy and schematic diagram of the distribution of low-dimensional perovskite at CsPbI3 grain boundaries.
In recent years, Institute of Physics, Chinese Academy of Sciences / Beijing National Research Center for Condensed Matter Physics Meng Qingbo’s team has developed a series of bulk and interface control methods to improve high-quality all-inorganic perovskite films, battery efficiency and stability Systematic research has been carried out. For example, a stable all-inorganic CsPb(Br,I)3 perovskite solar cell was successfully prepared based on solvent engineering (J. Mater. Chem. A, 2018, 6, 19810); using ammonium halide coordination to regulate the mesophase and CsPbI3 crystallization process, achieving a high filling factor and 18.71% photoelectric conversion efficiency (Adv. Funct. Mater., 2021, 31, 2010813); developed thiourea / ammonium thiocyanate low-temperature molten salt control strategy, using SCN- ions in molten salt and Pb2+ coordination regulates the growth of CsPbI3 crystal, obtaining high-quality CsPbI3 film and 20.1% photoelectric conversion efficiency (Angew. Chem. Int. Ed., 2021, 60, 36); Using a germanium doping strategy, the htm is significantly improved by in-situ generation of GeO2 thin layers to passivate grain boundaries and CsPbI3 perovskite film defects. l2CsPbI3 The humidity stability of the film and device, continuous operation under stable illumination and constant bias voltage 3000 hour battery performance is almost not attenuated (Adv. Energy Mater., 2022, 2103690).
Figure 2. Characterization of solar cell performance: (a) Transient fluorescence spectrum (TRPL) of CsPbI3 films prepared based on different organic cations ; dark-state space charge limited current (SCLC): b) comparison group and c) experimental group ; derived (d) Arrhenius relationship based on admittance spectrum, used to calculate defect energy levels and characteristic conversion frequencies, (e) defect state density distribution, f) interface defects; CsPbI3/spiro-OMeTAD interface composite Schematic diagram of: (g) comparison group and (h) experimental group.
Recently, the team discovered that phenyltrimethylquaternary ammonium cation (PTA+) has high symmetry and has weak intermolecular force . It has good thermal stability and good hydrophobic properties. .PTA+ can exist stably and interact with PbI2 during the annealing process of perovskite , forming wide-bandgap low-dimensional perovskite (1D PTAPbI3 and 2D in situ at the CsPbI3 perovskite grain boundary and surface. PTA2PbI4), this low-dimensional perovskite can effectively passivate the grain boundaries and surface defects of the CsPbI3 film, inhibit non-radiative recombination, and thereby reduce the opening voltage loss. At the same time, the hydrophobic low-dimensional perovskite can slow down the erosion of the black phase CsPbI3 by humidity, thereby improving the phase stability of the black phase CsPbI3. Based on the above-mentioned low-dimensional perovskite passivation strategy with high thermal stability, the efficiency of CsPbI3 inorganic perovskite solar cell reaches 21%, and the certified efficiency exceeds 20%. This is the highest efficiency reported to date for CsPbI3 perovskite solar cells. In addition, the above-mentioned devices also have excellent operational stability and humidity stability. This work has certain reference value for further improving the performance of CsPbI3 related optoelectronic devices and their application in stacked cells.
Figure 3. Continuous certification efficiency of all-inorganic batteries
The research results are based on “Temperature-Reliable Low-Dimensional Perovskites Passivated Black-phase CsPbI3 toward Stable and "Efficient Photovoltaics" was published on Angewandte Chemie International Edition (DOI: 10.1002/anie.202201300). Tan Shan, a doctoral student in the Clean Energy Laboratory of the Beijing National Research Center for Condensed Matter Physics E02, Institute of Physics, Chinese Academy of Sciences, is the first author of the paper, and researchers Li Dongmei and Meng Qingbo of the Institute of Physics are the corresponding authors of the paper . This research was supported by the National Natural Science Foundation of China (11874402, 51872321, 52072402 and 51627803) and the Ministry of Science and Technology (2018YFB1500101).
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