Green Synthesis Of CsPbBr₃ Perovskite Based On Natural Deep Eutectic Solvent And Their Applications In Sensing

Perovskite nanocrystals have great promise in the fields of solar cells,light-emitting diodes（LED）and analytical sensing,due to their excellent optoelectronic properties such as high photoluminescence quantum yield（PLQY）,adjustable fluorescence wavelength,narrow full width at half maximum（FWHM）and wide spectral range（400–700 nm）.Currently,the prominent synthetic methods of PNCs include high-temperature thermal injection method（HI）and ligand assisted precipitation method（LARP）.Nevertheless,these two methods require a large volume of toxic organic solvents such as N,N-dimethyl sulfone（DMSO）,N,N-dimethylformamide（DMF）,toluene and hexane,which significantly limits the large-scale production and commercial application of PNCs.Therefore,the search for alternative environment friendly solvents and development of a novel method for green synthesis of PNCs becoming high priority.Based on the above,for the first time,we propose the use of Natural Deep Eutectic Solvents（NADESs）as new green solvents to synthesize PNCs,and high-quality CsPbBr₃PNCs were prepared.At the same time,combining the inherent extraction and intrinsic luminescence characteristics of NADESs,highly sensitive sensing detection of iodomethane（CH₃I）in the atmosphere and Pb²⁺in water has been successfully achieved.The main research contents are as follows:（1）In this work,high-quality CsPbBr₃PNCs were synthesized through LARP method,by using high polar thymol:lactic acid（Thy:LacA）as a precursor solvent of Cs,low polar thymol:octanol（Thy:Oct）as the precursor solvent of Pb and low polar thymol:acid（Thy:DecA）as antisolvent.This research indicated that NADESs not only as solvents,but also as a surface ligand.Optical performance and stability of CsPbBr₃PNCs were significantly improved.In comparison to the conventional LARP method,CsPbBr₃PNCs prepared by the improved method have higher PLOY（～96.8%）,narrower FWHM（～18.8 nm）,and more excellent stability（still maintaining 82.9%PL strength after 70 days）.In summary,this research provided a new strategy for green synthesis of PNCs and provided the feasibility for large-scale industrialized synthesis of high-quality PNCs.（2）Construction and application of high performance atmospheric CH₃I visualization sensor based on CsPbBr₃PNCs prepared by NADESs.In this study,high efficiency extraction of CH₃I gas was achieved by using low polarity L-Menthol:n-Octanol（Men:Oct）.Then I^-can be released from CH₃I by nucleophilic substitution reaction with oleylamine（OAm）.After that,halogen exchange reaction leads to redshift of fluorescence by adding CsPbBr₃PNCs prepared through Men:Oct and Thy:LacA₂（molar ratio=1:2）.Based on this,a fluorescent and colorimetric CH₃I gas sensor was designed.The experimental results show that shift of PL emission spectra（Δλ=λ-λ₀）exhibits a good linear relationship with the amount of CH₃I（R=0.981）and a low LODs=0.017μmol.This sensor exhibited high sensitivity,high selectivity and high visualization resolution.The sensor provided a novel approach for convenient and green detection of CH₃I in the atmosphere.（3）Preparation of CsPbBr₃PNCs based on intrinsic blue light NADESs for visual sensing of Pb²⁺in water samples.In this chapter,for the first time,Men:DecA₃has intrinsic blue fluorescence was synthesized by using Men as a hydrogen bond donor and DecA as a hydrogen bond acceptor at a molar ratio of 1:3.The hydrophobicity of Men:DecA₃and the complexation of-COOH with Pb²⁺to achieve excellent selective extraction performance for Pb²⁺in water.Then CsBr,HBr,oleic acid（OA）,and OAm were added to prepare green fluorescence CsPbBr₃PNC and the intrinsic blue fluorescence of Men:DecA₃can be used as background fluorescence to construct visual fluorescence sensor.Experimental results showed the content of Pb²⁺exhibits a good linear relationship with fluorescence intensity（R=0.998）and a low LOD=0.235nmol,and the sensing detection of trace Pb²⁺have been successfully implemented in actual water samples.