Preparation And Properties Of Perovskite Thin Film Photodetectors Based On Topological Insulator Bi₂Se₃ Electrode

Photodetectors are optoelectronic devices that convert photons into detectable and collectable electrical signals.There are different kinds of application fields for photodetectors that depends on the material and device structure.The photodetectors are employed almost everywhere,from small communication to large missile guidance.Among them,semiconductor materials have been the elements of the entire social technology revolution,and the arrival of the artificial intelligence era has further promoted the development speed of the semiconductor integrated circuit industry.The manufacture of a high-performance microchip involves a series of complex processes,so the future development of photodetectors is still extremely challenging.After investigating various semiconductor materials,the topological insulator Bi₂Se₃ and the perovskite materials with novel photoelectrical properties are adopted on photodetector construction.The as-fabricated photodetector exhibits good sensitivity towards broadband light(UV-VIS-Infrared).The detailed discussion are as follows:The topological insulator is a kind material with Dirac cone-like band structure.They possesses insulator state in bulk and metal state at surface with self-selective momentum spiral locking and time inversion symmetry protection.Perovskite materials are a new class of materials with high absorption coefficients and long carrier diffusion lengths.In this thesis,high-quality topological insulator Bi₂Se₃ materials were firstly grown by molecular beam epitaxy(MBE)method followed by patterning using photolithography.Then,the perovskite precursor solution(FA_0.85Cs_0.15Pb I₃)were coated onto the pattered electrode by one-step spin coating process to construct the photodetector.At last,the electric and photoelectric properties were measured.The experiment results demonstrated that the prepared Bi₂Se₃-FA_0.85Cs_0.15Pb I₃-Bi₂Se₃ photodetector showed obvious sensitivity to 650nm irradiation and the switch ratio was 0.8×10⁵ with good repeatability.Responsivity,external quantum efficiency and detection rate could reach 8.4 AW^-1,1604%and 1.7×10¹³Jones,respectively,which is not only better than the perovskite thin film detector using Au as the electrode,but also superior to other electrode based perovskite film photodetectors It is worth mentioning that the Bi₂Se₃-based perovskite thin film photodetector exhibits a distinct optical response to near-infrared light(NIR)at 980 nm due to the contribution of the topological insulator Bi₂Se₃ layer.In summary,current topographic insulator-based perovskite thin film photodetectors are expected to be used in broadband and high performance optoelectronic applications in the future.