Stable Perovskite Quantum Dots Enabled by Colorless Polyimide as the Surface Coating Material
Perovskite quantum dots have been widely used due to their high photoluminescence quantum efficiencies,narrow FWHM,tunable band gap and so on.However,perovskite quantum dots suffer from poor stability in the presence of polar solvent,heat,air and illumination.Surface coating is one of the effective ways to overcome this issue.Polymer-coated perovskite quantum dots exhibit high resistance to moisture,but most of transparent polymers have poor thermal stability.Colorless polyimides(CPI)exhibit good heat resistance,chemical stability,mechanical property and dielectric property,in addition to high transparency.Herein,we introduce a way to improve the stability of CsPbBr3 quantum dots via CPI coating,in which CsPbBr3 quantum dots are first mixed with polyamic acid and then CPI coated CsPbBr3 quantum dots are formed through thermal amination.Polyamic acid can interact with CsPbBr3 quantum dots via amine groups and carboxyl groups,which is favorable to the dispersion of CsPbBr3 quantum dots in the polymer matrix and thus prevent the decline of luminescent property induced by the aggregation of quantum dots during film formation.As a result,the as-prepared CPI-coated CsPbBr3 quantum dots possess high stability under moisture and UV light,in addition to good luminescent property.
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