Low-Dimensional Organic Aromatic Ammonium Halides Phosphorescent Study At Room Temperature

Room-temperature phosphorescence（RTP）materials have great application potential in biological imaging,organic photoelectricity,information anti-counterfeiting and encryption,etc.However,the performance of RTP materials is far from meeting the needs of practical applications.In order to develop RTP materials with excellent properties,this thesis starts with the luminescence mechanism,uses the external heavy atom effect to promote intersystem crossing（ISC）to increase triplet excitons and reduce the quenching of triplet excitons to construct a series of low-dimensional crystalline halide RTP materials.1.Two kinds of metal-free two-dimensional（2D）layered ammonium halide salts（3,4-methylenedioxyphenethylamine bromate（HLB）and hydrochloride（HLC））were obtained by ethanol recrystallization.The 2D rigid laminate structure and the external heavy atom effect of halogen atoms make HLB and HLC show strong green RTP emission.At the same time,phosphorescent groups with different triplet energy levels were doped into HLB,HLC or phenylethylamine salt.High-efficiency full color ultralong RTP could be realized through F（?）rster energy transfer between the subject and the object,with phosphor quantum yield as high as 18.7%and lifetime as high as 1.7 s.And long-life RTP materials with the same performance above 10 g level could be obtained by simple solution synthesis method at one time.Information inks made of these RTP materials can make various patterns on filter paper,moreover,the fluorescence and phosphorescence emission of these patterns are very sensitive to excitation wavelength and acid-base vapor,so they can be applied to multiple complex anti-counterfeiting and fluorescence/phosphorescence dual-mode chemical sensors.2.In order to obtain blue RTP with long life and high quantum yield,two novel zero-dimensional（0D）organic-inorganic hybrid metal halides（PA6In Cl9 and PA4In Cl7）were synthesized by hydrothermal method with indium chloride（In Cl₃）and aniline hydrochloride（PACl）.PA6In Cl9 shows stronger RTP emission,and the quantum yield of phosphorescence could be increased from 25.2%to 42.8%under continuous ultraviolet irradiation.PA4In Cl7 shows weaker RTP emission,however,it can realize lattice transformation to PA6In Cl9 under the action of mechanical external force,thus improving RTP quantum yield.Time-resolved spectral measurements show that the lifetime of PA6In Cl9 and PA4In Cl7 is as high as 1.2 s.In addition,when Sb³⁺with orange triplet emission was introduced into PA6In Cl9 lattice,white and orange pure RTP with phosphorescence quantum yield close to 100%could be realized,in which the color rendering index（CRI）of white pure phosphorescence is close to 90.Therefore,this work not only overcomes the long-standing problems of low quantum yield and short lifetime of blue RTP,but also obtains high-efficiency white RTP,which provides a feasible method for achieving high quantum efficiency and has great application potential in the fields of optical devices and intelligent materials.3.Red RTP is highly appreciated in the fields of bio-imaging and luminescence probe for its long luminescence wavelength.In order to obtain red RTP material,2D metal halide PAD was synthesized by recrystallization from aniline cation and metal halide Cd Cl₂.PAD has red and blue phosphorescence emission,blue phosphorescence lifetime of 1.2 s and red phosphorescence lifetime of 14.5 ms.By introducing metal ions Mn²⁺,the luminous quantum yield of red RTP is close to 100%owing to the dexter energy transfer between organic and inorganic components is promoted.At the same time,the luminescent material has good stability in the air,so it has broad application prospects in the fields of red LEDs,biological imaging,intelligent anti-counterfeiting,etc.