Investigation On Optical Properties And Optoelectronic Device Application Of Low-Dimension Perovskite Materials

Recently,nano-optoelectronic devices and integrated systems have become the key research directions in the field of optical communication.As the optical signal transmitter and receiver of the optical communication system,semiconductor lasers and photodetectors directly affect the performance of the entire system.Therefore,the selection of semiconductor materials for lasers and photodetectors is particularly important.Last few years,three-dimensional lead halide perovskite nanomaterials have received great attention due to their excellent optoelectronic properties,such as higher carrier mobility,full-spectrum emission,and narrow full width at half maximum(FWHM).However,the long-term instability,lead toxicity,and low photoluminescence quantum yield(PLQY)of three-dimensional perovskite film are still the challenges which hinder its commercial application.In order to solve these problems,reducing the dimension of the perovskite from the molecular structure is an effective strategy to achieve low-toxicity,high stability,and higher PLQY.For low-dimensional perovskites,photogenerated carriers are effectively confined in the octahedron,which greatly increases the possibility of radiation recombination,thereby effectively improving the PLQY of the perovskite nanomaterials.In addition,low-dimensional perovskite also has a series of unique optoelectronic properties,such as:strong quantum confinement,tunable bandgap energy,and maximum exciton binding energy.Therefore,low-dimensional perovskites show a good application prospect in optoelectronic devices.However,compared to three-dimensional perovskites,the research on low-dimensional perovskites is still in the early stages of development.The luminescence mechanisms are unclear,and the applications of photoelectronic devices are still scarce.In this paper,we mainly study on the crystal structure,synthesis methods and photoelectric properties of low-dimensional perovskite.The application of low-dimensional perovskite in micro-nano lasers and photodetectors is emphasized.This study mainly includes the following aspects:(1)The synthesis and lasing performance of three-dimensional perovskite material based on surface plasmons:The regular three-dimensional perovskite CsPbBr₃nanocubes were synthesized using two-step method.In order to further improve its optical properties,Au nanoparticles were introduced into the PEDOT:PSS buffer layer.Due to the localized surface plasmon resonance(LSPR)effect,the optical properties of CsPbBr₃nanocubes were greatly improved.We designed a laser testing system by using an ultrafast femtosecond laser as the excitation source,to study the lasing characteristics of three-dimensional perovskite nanocubes based on surface plasmons.By introducing Au particles with surface plasmon enhancement effect,the laser threshold of three-dimensional perovskite nanocubes was effectively reduced.(2)The synthesis of low-dimensional perovskite materials:The two-dimensional perovskite PEA₂FA₂Pb₃Br₁₀ film was prepared via an anti-solvent assisted crystallization method.A uniform and dense thin film has been obtained by adding small amount of trioctylphosphine oxide(TOPO)to the anti-solvent chlorobenzene,and the emission peak is about 535 nm;A one-dimensional perovskite Cs Cu₂I₃ film was prepared by an anti-solvent-assisted recrystallization method.The synthesized Cs Cu₂I₃shown high crystallinity and phase purity,and the film presents uniform and dense pine-leave-shaped micro-robs.It has good stability and excellent optical properties;The zero-dimensional perovskite Cs₄Pb Br₆ hexagonal microdisks with regular morphology were prepared by a room-temperature reverse microemulsion method.The crystal structure shown rhombohedral phase and high crystalline quality.The synthesized Cs₄Pb Br₆ microdisks has excellent optical characteristics and good long-term stability.By tuning the amounts of surfactants(OA:OAm)in the precursor solution,the conversion between three-dimensional perovskite CsPbBr₃ and zero-dimensional perovskite Cs₄Pb Br₆was achieved.The femtosecond transient absorption measurements proved that the fluorescence of zero-dimensional perovskite Cs₄Pb Br₆ is mainly derived from the polaron in Cs₄Pb Br₆ rather than the CsPbBr₃ impurities.(3)Lasing performances of low-dimensional perovskite materials:Based on the synthesized high-quality perovskite nanomaterials,we used an ultrafast femtosecond laser as the excitation source to study the lasing performance of low-dimensional perovskites.First,a two-photon femtoseconds laser was used to pump the two-dimensional perovskite PEA₂FA₂Pb₃Br₁₀ thin film.At room temperature,a low-threshold,high-quality up-conversion random laser emission was obtained.In addition,a zero-dimensional perovskite Cs₄Pb Br₆ microdisks with regular morphology and smooth surface was pumped by using one-and two-photon lasers.The results show that a single Cs₄Pb Br₆ microdisk can be used not only as an optical gain medium,but also as an ideal whispering-gallery-mode(WGM)microcavity.Photons propagate and oscillate inside the six side faces of hexagonal MDs of Cs₄Pb Br₆,which generates resonance under certain conditions,thereby achieving a WGM single-mode laser output.(4)Light response performance of low-dimensional perovskite materials:Based on the synthesis of high-quality low-dimensional perovskite materials,the low-dimensional perovskite photodetectors were designed and the light response performance was studied.First,a two-dimensional perovskite PEA₂FA₂Pb₃Br₁₀ film was grown on the gold interdigital electrode by self-assembly directly in situ,forming a metal/semiconductor/metal(Au/PEA₂FA₂Pb₃Br₁₀/Au)structure photoconductive detector.Under light,photo-generated carriers were transmitted to the circuit through the interdigital electrode,realizing the conversion from optical signals to electrical signals.Under 450 nm excitation light,the device exhibited a lower dark current,which is critical to the noise performance of the photodetector.By analyzing the device,I_light/I_dark,light responsivity,specific detectivity,and external quantum efficiency were0.71×10⁴,?4.22 m A/W,?1.69×10¹⁰Jones,and?1.2%.The performance is better than the previously reported perovskite photodetectors.In addition,the zero-dimensional perovskite Cs₄Pb Br₆ microdisks colloidal solution was sprayed onto the interdigitated electrodes to prepare an Au/Cs₄Pb Br₆/Au photodetector.Under 405 nm light,a lower dark current(approximately 4 p A)was achieved.The I_light/I_dark ratio,optical responsivity,specific detectivity,and external quantum efficiency are 1.65×10²,1.95m A/W,1.33×10⁹ Jones,and 0.6%,respectively.The corresponding optical response time?_r/?_f is 38 ms/43 ms;Finally,to achieve an environmentally friendly photodetector,the one-dimensional lead-free perovskite Cs Cu₂I₃ was directly grown on the Au interdigitated electrode in situ as a photosensitive layer to prepare an Au/Cs Cu₂I₃/Au photoconductive deep ultraviolet detector.The results shown that the detector was almost insensitive to 405 nm visible light but was apparently sensitive to 265 nm and365 nm light.This shown that the one-dimensional lead-free perovskite Cs Cu₂I₃ thin film device can be used as a solar blind detector.Under 265 nm light excitation,the device shown good repeatability,fast response(t_r/t_f of 40/76 ms),and a high I_light/I_darkratio.Furthermore,it is obtained that the responsivity,specific detectivity,and external quantum efficiency were 22.1 m A/W,1.2×10¹¹ Jones,and 10.3%,respectively.These results indicated that low-dimensional perovskite photodetectors have broad application prospects in next-generation optoelectronic devices.