[ Instrument R & D of Instrument Network ] Inorganic organic hybrid lead halogen perovskite ferroelectric materials have excellent ferroelectric properties and semiconductor properties, and have become the frontier research direction of optoelectronic functional materials in recent years. However, lead toxicity in such materials has been a problem that has plagued its further development. In lead-halogen perovskite materials, use trivalent metals (In3 +, Bi3 +, Sb3 +) and monovalent metals (Cu +, K +, Na +, Li +, Ag +) to replace the toxic element Pb2 + to construct metal-halogen double perovskite hybrid materials Is an effective method and strategy for designing and synthesizing non-lead inorganic organic hybrid perovskite materials. At the same time, this type of material also has the characteristics of long carrier life, high defect tolerance, low exciton binding energy, etc., which is expected to promote the further development of high-performance green optoelectronic materials.
The team of Luo Junhua, a researcher of "Inorganic Optoelectronic Functional Crystal Materials", State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences has been a key project of the National Natural Science Foundation of China, the National Outstanding Youth Fund, the Basic Frontier 0-1 Original Innovation Project of the Chinese Academy of Sciences, and a strategic leader With special funding, based on the three-dimensional perovskite material CsPbBr3, a two-dimensional double-layer non-lead bimetallic halogen inorganic organic hybrid "optical ferroelectric semiconductor" (n-propylammonium) 2CsAgBiBr7 was prepared.
Ferroelectric semiconductors are ferroelectrics that also have the physical properties of semiconductors. Ferroelectric semiconductor physics is a new field of ferroelectric physics developed in the early 1960s. Due to the difference in energy gap width Eg, ferroelectric semiconductors are divided into wide Bandgap ferroelectric semiconductors and narrow bandgap ferroelectric semiconductors â€¢ Wide bandgap such as barium titanate, lithium niobate and Aâ…¤2BVI2 type compounds; narrow bandgap such as AIVBâ…£ type semiconductors â€¢ Aâ…¤Bâ…¥Câ…¦ which is ferroelectric and photoconductive semiconductor at the same time Egâ‰ˆ2eV of SbSI of type compound. In ferroelectric semiconductors, the electronic system interacts with the crystal lattice, and the interaction between electrons and elementary excitation (such as soft mode) leads to a series of physical phenomena.
Studies have shown that the metal halide octahedral distortion and the ordering of organic cations synergistically induce the ferroelectric spontaneous polarization of the compound; at the same time, the material exhibits good photoelectric detection performance for the optical radiation in the intrinsic absorption region, showing a large The photoelectric detection on / off ratio (104), fast response time (141 Î¼s) and high detection rate (5.3 Ã— 1011 Jones). This work provides a new strategy for the design of non-lead "photoferroelectric semiconductor" materials.
Ferroelectric materials are a type of functional materials with spontaneous polarization and the spontaneous polarization can be reversed under the action of an external electric field. Its research involves phase transition, symmetry breaking, polarity, spontaneous polarization, and thus has a nonlinear frequency doubling , Piezoelectricity, pyroelectricity, ferroelectricity, flexure electricity, electro-optic effect and high dielectric constant and other properties, have important applications in storage, ultrasound, optoelectronic technology.
Ferroelectric material refers to a type of material with ferroelectric effect, which is a branch of pyroelectric material. Ferroelectric materials and their application research has become one of the hot research topics in the field of condensed matter physics and solid electronics. The reason for the crystals is that they have quite excellent properties. Many electro-optic crystals and piezoelectric materials are ferroelectric crystals. Ferroelectric crystals have important significance both in technology and theory.
Previously, the team started by studying the phase transition of the structure of matter caused by molecular motion (Adv. Fuct. Mater., 2012, 22, 4855), and further constructed a series of design strategies that induced the polarization effect induced by the phase transition of the solid symmetric broken structure Polar photoelectric crystal materials; at the same time, because the inorganic organic hybrid metal halide perovskite materials have high light absorption and excellent carrier transmission and other semiconductor properties, the team started from in-depth research on the photoelectric properties of inorganic organic hybrid semiconductors, further in inorganic organic Introduce ferroelectricity into hybrid semiconductors, use the response of the semiconductor to the light field in combination with the bulk photovoltaic effect generated by ferroelectric polarization to innovatively propose and carry out the research of "inorganic-organic hybrid opto-ferroelectric semiconductors". Carry out systematic and in-depth research on the structural design, crystal growth, optoelectronic device assembly, optoelectronic performance regulation and other aspects of the materials of "Ferroelectric Semiconductor" materials and achieve a series of innovative research progress to achieve the ferroelectric photovoltaic effect, multi-axis ferroelectric photovoltaic, and further use The ferroelectric photovoltaic effect realizes self-driven photoelectric detection and large polarization ratio polarized photoelectric detection.
Source: Encyclopedia, Fujian Institute of Material Structure
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